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Saady M, Shoman NA, Teaima M, Abdelmonem R, El-Nabarawi MA, Elhabal SF. Fabrication of gastro-floating sustained-release etoricoxib and famotidine tablets: design, optimization , in-vitro, and in-vivo evaluation. Pharm Dev Technol 2024:1-16. [PMID: 38607310 DOI: 10.1080/10837450.2024.2343320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 04/11/2024] [Indexed: 04/13/2024]
Abstract
In this study, a new gastro-floating sustained-release tablet (GFT) with a combination of Etoricoxib (ET) and Famotidine (FM) was successfully developed. GFTs were prepared by using a combination of hydrophilic swellable natural/semi-synthetic polymers as a controlled-release layer. Through a 24 full factorial statistical experimental design, the effects of formulation factors on the release of GFTs were conducted. The ideal floating tablet (FT) comprised konjac-gum (150 mg), guar-gum (26.57 mg), xanthan-gum (54.17 mg), and HPMC-K15-M (69.25 mg). The ideal FT exhibited a high swelling index (SI) (297.7%) and rapid FLT (around 50 s) in 0.1 N HCl as well as controlled release of ET (22.43% in 1 h and 77.47% in 8 h) and FM (24.89% in 1 h and 93.82% in 8 h) with the absence of any drug-excipient interactions. The AUC0∼72 (ng h/mL) of ET and FM in the GFTs were approximately double-fold of the market, respectively. The relative bioavailability was (207.48 ± 12.02% and 208.51 ± 13.11%) compared with commercial tablets. The X-ray imaging showed a promising buoyancy ability for approximately 8 h. These findings revealed the successful preparation of the sustained-release floating tablet with improved dual drug delivery.
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Affiliation(s)
- Marwa Saady
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Nabil A Shoman
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Ahram Canadian University, Giza, Egypt
| | - Mahmoud Teaima
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Rehab Abdelmonem
- Department of Industrial Pharmacy, College of Pharmaceutical Sciences and Drug Manufacturing, Misr University for Science and Technology (MUST), Giza, Egypt
| | - Mohamed A El-Nabarawi
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Sammar Fathy Elhabal
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Modern University for Technology and Information (MTI), Mokattam, Cairo, Egypt
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2
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Li B, Inscoe CR, Xu S, Capo T, Tyndall DA, Lee YZ, Lu J, Zhou O. A carbon nanotube x-ray source array designed for a new multisource cone beam computed tomography scanner. Phys Med Biol 2024; 69:075028. [PMID: 38471174 DOI: 10.1088/1361-6560/ad3323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Accepted: 03/12/2024] [Indexed: 03/14/2024]
Abstract
Cone beam computed tomography (CBCT) is known to suffer from strong scatter and cone beam artifacts. The purpose of this study is to develop and characterize a rapidly scanning carbon nanotube (CNT) field emission x-ray source array to enable a multisource CBCT (ms-CBCT) image acquisition scheme which has been demonstrated to overcome these limitations. A CNT x-ray source array with eight evenly spaced focal spots was designed and fabricated for a medium field of view ms-CBCT for maxillofacial imaging. An external multisource collimator was used to confine the radiation from each focal spot to a narrow cone angle. For ms-CBCT imaging, the array was placed in the axial direction and rapidly scanned while rotating continuously around the object with a flat panel detector. The x-ray beam profile, temporal and spatial resolutions, energy and dose rate were characterized and evaluated for maxillofacial imaging. The CNT x-ray source array achieved a consistent focal spot size of 1.10 ± 0.04 mm × 0.84 ± 0.03 mm and individual beam cone angle of 2.4°±0.08 after collimation. The x-ray beams were rapidly switched with a rising and damping times of 0.21 ms and 0.19 ms, respectively. Under the designed operating condition of 110 kVp and 15 mA, a dose rate of 8245μGy s-1was obtained at the detector surface with the inherent Al filtration and 2312μGy s-1with an additional 0.3 mm Cu filter. There was negligible change of the x-ray dose rate over many operating cycles. A ms-CBCT scan of an adult head phantom was completed in 14.4 s total exposure time for the imaging dose in the range of that of a clinical CBCT scanner. A spatially distributed CNT x-ray source array was designed and fabricated. It has enabled a new multisource CBCT to overcome some of the main inherent limitations of the conventional CBCT.
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Affiliation(s)
- Boyuan Li
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Christina R Inscoe
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Shuang Xu
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Timothy Capo
- Independent Consultant, United States of America
| | - Donald A Tyndall
- Division of Diagnostic Sciences, Adams School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Yueh Z Lee
- Department of Radiology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Jianping Lu
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Otto Zhou
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
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Rossignol J, Bélanger G, Gaudreault D, Therrien AC, Bérubé-Lauziére Y, Fontaine R. Time-of-flight scatter rejection in x-ray radiography. Phys Med Biol 2024; 69:055027. [PMID: 38232398 DOI: 10.1088/1361-6560/ad1f85] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 01/17/2024] [Indexed: 01/19/2024]
Abstract
Objective.Time-of-flight (TOF) scatter rejection allows for identifying and discarding scattered photons without the use of an anti-scatter grid (ASG). Although TOF scatter rejection was initially presented for cone-beam computed tomography, we propose, herein, to extend this approach to x-ray radiography. This work aims to evaluate with simulations if TOF scatter rejection can outperform ASGs for radiography.Approach.GATE was used to simulate the radiography of a head and a torso and a water cylinder with bone inserts in a system with total timing jitters from 0 ps up to 500 ps full-width-at-half-maximum. The transmission factor of TOF scatter rejection for primary and scattered photons was evaluated as if it were a virtual ASG.Main results.With a total timing jitter of 50 ps, TOF scatter rejection can reach a selectivity of 4.93 with a primary photons transmission of 99%. Reducing the timing jitter close to 0 ps increases the selectivity up to 15.85 for a head and torso radiography, outperforming typical ASGs which usually have a selectivity from 2.5 to 10 with a primary photons transmission from 50% to 70%.Significance.This suggests that TOF scatter rejection may be suitable to replace ASGs in applications requiring lower radiation exposure if sufficiently low timing jitter is achieved.
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Affiliation(s)
- J Rossignol
- Institut Interdisciplinaire d'Innovation Technologique (3IT), Université de Sherbrooke, Sherbrooke, Québec, Canada
- Département de Génie Électrique et Génie Informatique, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - G Bélanger
- Institut Interdisciplinaire d'Innovation Technologique (3IT), Université de Sherbrooke, Sherbrooke, Québec, Canada
- Département de Génie Électrique et Génie Informatique, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - D Gaudreault
- Institut Interdisciplinaire d'Innovation Technologique (3IT), Université de Sherbrooke, Sherbrooke, Québec, Canada
- Département de Génie Électrique et Génie Informatique, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - A C Therrien
- Institut Interdisciplinaire d'Innovation Technologique (3IT), Université de Sherbrooke, Sherbrooke, Québec, Canada
- Département de Génie Électrique et Génie Informatique, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Y Bérubé-Lauziére
- Département de Génie Électrique et Génie Informatique, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - R Fontaine
- Institut Interdisciplinaire d'Innovation Technologique (3IT), Université de Sherbrooke, Sherbrooke, Québec, Canada
- Département de Génie Électrique et Génie Informatique, Université de Sherbrooke, Sherbrooke, Québec, Canada
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Liu L, Hu H, Pan W, Gao H, Song J, Feng X, Qu W, Wei W, Yang B, Wei H. Robust Organogel Scintillator for Self-healing and Ultra-flexible X-ray Imaging. Adv Mater 2023:e2311206. [PMID: 38104266 DOI: 10.1002/adma.202311206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/12/2023] [Indexed: 12/19/2023]
Abstract
Metal halide scintillators serve as promising candidates for X-ray detection due to their high attenuation coefficients, high light yields, and low-cost solution-processable characteristics. However, the issues of humidity/thermal quenching and mechanical fragility, remain obstacles to the broad and diversified development of metal halide scintillators. Here, this work reports a lead-free, water-stable, stretchable, and self-healing (ethylenebis-triphenylphosphonium manganese (II) bromide (C38 H34 P2 )MnBr4 organogel scintillator that meets X-ray imaging in complex scenarios. The robust organogel scintillator can be stretched with elongation up to 1300% while maintaining the scintillation properties. Activated by the dynamic hydrogen bonds and coordination bonds design, the organogel scintillator exhibits excellent self-healing properties at room temperature to alleviate the vignetting problem of the rigid scintillator films, the X-ray imaging resolution can reach 16.7 lp mm-1 . The organogel scintillator can also realize flexible and self-healing X-ray imaging in water, providing a design path for portable devices in harsh conditions.
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Affiliation(s)
- Lulu Liu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Haijing Hu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Wanting Pan
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Hang Gao
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Jinmei Song
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Xiaopeng Feng
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Wei Qu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Wei Wei
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun, 130012, P. R. China
| | - Bai Yang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
- Optical Functional Theragnostic Joint Laboratory of Medicine and Chemistry, The First Hospital of Jilin University, Changchun, 130012, P. R. China
| | - Haotong Wei
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
- Optical Functional Theragnostic Joint Laboratory of Medicine and Chemistry, The First Hospital of Jilin University, Changchun, 130012, P. R. China
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Aubert S, Tanguay J. Signal-difference-to-noise comparison of temporal subtraction, kV-switching dual-energy and photon-counting dual-energy x-ray angiography. Med Phys 2023; 50:7400-7414. [PMID: 37877679 DOI: 10.1002/mp.16800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 09/11/2023] [Accepted: 10/02/2023] [Indexed: 10/26/2023] Open
Abstract
BACKGROUND Dual-energy (DE) x-ray angiography with photon-counting detectors (PCDs) may enable single-exposure DE imaging of coronary vasculature. PURPOSE To compare the iodine signal-difference-to-noise ratio (SDNR) of single-exposure DE angiography with digital subtraction angiography (DSA) and kV-switching DE angiography for matched patient x-ray exposure. METHODS In a phantom study, we determined the technique parameters that maximized the iodine SDNR per root entrance air kerma for DSA, kV-switching DE angiography and single-exposure DE angiography. We measured SDNR from images of a phantom consisting of an iodine step-wedge immersed in a water tank of either 20 or 30 cm in thickness. We also imaged a phantom with simulated vessels embedded in background clutter and measured vessel SDNR. For this second phantom, we also applied anti-correlated noise reduction (ACNR) and calculated the resulting iodine SDNR. All images were acquired using a cadmium telluride PCD with two energy bins and analog charge summing for charge sharing suppression. The energy-discrimination capabilities were only used for the single-exposure DE approach. Optimized techniques were compared in terms of SDNR per root air kerma for two levels of x-ray scatter. RESULTS For the same patient x-ray exposure, the SDNR of single-exposure DE imaging without ACNR was 75% to 85% of that of kV-switching DE imaging (also without ACNR) and DSA, the latter two of which had nearly equal SDNR. The single-exposure DE approach required ∼50% of the tube load of the kV-switching approach to achieve the same SDNR. For matched patient air kermas, the single exposure approach required only ∼25% of the tube load of the kV-switching approach. ACNR increased SDNR by 2.4 and 3.0 for kV-switching and single-exposure DE imaging, respectively. CONCLUSIONS Photon-counting, single-exposure DE angiography can suppress soft tissues and provide iodine SDNR levels comparable to DSA and kV-switching DE angiography for matched patient radiation exposures. When ACNR is used to reduce DE image noise, the SDNR of single-exposure DE imaging and kV-switching DE imaging exceed that of DSA by more than a factor of two. Compared to kV-switching DE imaging, single-exposure DE imaging requires substantially lower tube loading to achieve the same SDNR.
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Affiliation(s)
- Sarah Aubert
- Department of Physics, Toronto Metropolitan University (formerly Ryerson University), Toronto, Canada
| | - Jesse Tanguay
- Department of Physics, Toronto Metropolitan University (formerly Ryerson University), Toronto, Canada
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Ghosh J, O’Neill J, Masteghin MG, Braddock I, Crean C, Dorey R, Salway H, Anaya M, Reiss J, Wolfe D, Sellin P. Surfactant-Dependent Bulk Scale Mechanochemical Synthesis of CsPbBr 3 Nanocrystals for Plastic Scintillator-Based X-ray Imaging. ACS Appl Nano Mater 2023; 6:14980-14990. [PMID: 37649835 PMCID: PMC10463220 DOI: 10.1021/acsanm.3c02531] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 07/21/2023] [Indexed: 09/01/2023]
Abstract
We report a facile, solvent-free surfactant-dependent mechanochemical synthesis of highly luminescent CsPbBr3 nanocrystals (NCs) and study their scintillation properties. A small amount of surfactant oleylamine (OAM) plays an important role in the two-step ball milling method to control the size and emission properties of the NCs. The solid-state synthesized perovskite NCs exhibit a high photoluminescence quantum yield (PLQY) of up to 88% with excellent stability. CsPbBr3 NCs capped with different amounts of surfactant were dispersed in toluene and mixed with polymethyl methacrylate (PMMA) polymer and cast into scintillator discs. With increasing concentration of OAM during synthesis, the PL yield of CsPbBr3/PMMA nanocomposite was increased, which is attributed to reduced NC aggregation and PL quenching. We also varied the perovskite loading concentration in the nanocomposite and studied the resulting emission properties. The most intense PL emission was observed from the 2% perovskite-loaded disc, while the 10% loaded disc exhibited the highest radioluminescence (RL) emission from 50 kV X-rays. The strong RL yield may be attributed to the deep penetration of X-rays into the composite, combined with the large interaction cross-section of the X-rays with the high-Z atoms within the NCs. The nanocomposite disc shows an intense RL emission peak centered at 536 nm and a fast RL decay time of 29.4 ns. Further, we have demonstrated the X-ray imaging performance of a 10% CsPbBr3 NC-loaded nanocomposite disc.
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Affiliation(s)
- Joydip Ghosh
- Department
of Physics, University of Surrey, Guildford GU2 7XH, U.K.
| | - Joseph O’Neill
- Department
of Physics, University of Surrey, Guildford GU2 7XH, U.K.
| | - Mateus G. Masteghin
- Advanced
Technology Institute, University of Surrey, Guildford GU2 7XH, U.K.
| | - Isabel Braddock
- Department
of Physics, University of Surrey, Guildford GU2 7XH, U.K.
| | - Carol Crean
- Department
of Chemistry, University of Surrey, Guildford GU2 7XH, U.K.
| | - Robert Dorey
- School
of Mechanical Engineering Sciences, University
of Surrey, Guildford GU2 7XH, U.K.
| | - Hayden Salway
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, U.K.
| | - Miguel Anaya
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, U.K.
- Departamento
Física de la Materia Condensada, Instituto de Ciencia
de Materiales de Sevilla, Universidad de
Sevilla−CSIC, Avenida Reina Mercedes SN, Sevilla 41012, Spain
| | - Justin Reiss
- Applied
Research
Laboratory, Materials Science and Engineering Department, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Douglas Wolfe
- Applied
Research
Laboratory, Materials Science and Engineering Department, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Paul Sellin
- Department
of Physics, University of Surrey, Guildford GU2 7XH, U.K.
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Treb K, Radtke J, Culberson WS, Li K. Simultaneous photon counting and charge integrating for pulse pile-up correction in paralyzable photon counting detectors. Phys Med Biol 2023; 68:10.1088/1361-6560/ace2a9. [PMID: 37379858 PMCID: PMC10415089 DOI: 10.1088/1361-6560/ace2a9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 06/28/2023] [Indexed: 06/30/2023]
Abstract
Objective.In photon counting detectors (PCDs), electric pulses induced by two or more x-ray photons can pile up and result in count losses when their temporal separation is less than the detector dead time. The correction of pulse pile-up-induced count loss is particularly difficult for paralyzable PCDs since a given value of recorded counts can correspond to two different values of true photon interactions. In contrast, charge (energy) integrating detectors work by integrating collected electric charge induced by x-rays over time and do not suffer from pile-up losses. This work introduces an inexpensive readout circuit element to the circuits of PCDs to simultaneously collect time-integrated charge to correct pile-up-induced count losses.Approach.Prototype electronics were constructed to collect time-integrated charges simultaneously with photon counts. A splitter was used to feed the electric signal in parallel to both a digital counter and a charge integrator. After recording PCD counts and integrating collected charge, a lookup table can be generated to map raw counts in the total- and high-energy bins and total charge to estimate pile-up-free true counts. Proof-of-concept imaging experiments were performed with a CdTe-based PCD array to test this method.Main results.The proposed electronics successfully recorded photon counts and time-integrated charge simultaneously, and whereas photon counts exhibited paralyzable pulse pile-up, time-integrated charge using the same electric signal as the counts measurement was linear with x-ray flux. With the proposed correction, paralyzable PCD counts became linear with input flux for both total- and high-energy bins. At high flux levels, uncorrected post-log measurements of PMMA objects severely overestimated radiological path lengths for both energy bins. After the proposed correction, the non-monotonic measurements again became linear with flux and accurately represented the true radiological path lengths. No impact on the spatial resolution was observed after the proposed correction in images of a line-pair test pattern.Significance.Time-integrated charge can be used to correct for pulse pile-up in paralyzable PCDs where analytical solutions may be difficult to use, and integrated charge can be collected simultaneously with counts using inexpensive electronics.
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Affiliation(s)
- Kevin Treb
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI, United States of America
| | - Jeff Radtke
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI, United States of America
| | - Wesley S Culberson
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI, United States of America
| | - Ke Li
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI, United States of America
- Department of Radiology, School of Medicine and Public Health, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI, United States of America
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Sauer TJ, Bejan A, Segars P, Samei E. Development and CT image-domain validation of a computational lung lesion model for use in virtual imaging trials. Med Phys 2023; 50:4366-4378. [PMID: 36637206 PMCID: PMC10338637 DOI: 10.1002/mp.16222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 11/03/2022] [Accepted: 12/14/2022] [Indexed: 01/14/2023] Open
Abstract
PURPOSE Computational abnormalities (e.g., lesion models) for use in medical imaging simulation studies are frequently generated using data collected from clinical images. Although this approach allows for highly-customizable lesion detectability studies on clinical computed tomography (CT) data, the ground-truth lesion models produced with this method do not provide a sufficiently realistic lesion morphology for use with current anthropomorphic simulation studies. This work is intended to demonstrate that the new anatomically-informed lesion model presented here is not inferior to the previous lesion model under CT imaging, and can therefore provide a more biologically-informed model for use with simulated CT imaging studies. METHODS The lesion model was simulated initially from a seed cell with 10 μm diameter placed in an anatomical location within segmented lung CT and was allowed to reproduce locally within the available solid angle in discrete time-intervals (corresponding to synchronous cell cycles) up to a size of ∼200 μm in diameter. Daughter cells of generation G were allowed also to reproduce on the next available time-step given sufficient space. At lesion sizes beyond 200 μm in diameter, the health of subregions of cells were tracked with a Markov chain technique, indicating which regions were likely to continue growing, which were likely stable, and which were likely to develop necrosis given their proximity to anatomical features and other lesion cells. For lesion sizes beyond 500 μm, the lesion was represented with three nested, triangulated surfaces (corresponding to proliferating, dormant, and necrotic regions), indicating how discrete volumes of the lesion were behaving at a particular time. Lesions were then assigned smoothly-varying material properties based on their cellular level health in each region, resulting in a multi-material lesion model. The lesions produced with this model were then voxelized and placed into lung CT images for comparison with both prior work and clinical data. This model was subject to an observer study in which cardiothoracic imaging radiologists assessed the realism of both clinical and synthetic lesions in CT images. RESULTS The useable outputs of this work were voxel- or surface-based, validated, computational lesions, at a scale clearly visible on clinical CT (3-4 cm). Analysis of the observer study results indicated that the computationally-generated lesions were indistinguishable from clinical lesions (AUC = 0.49, 95% CI = [0.36, 0.61]) and non-inferior to an earlier image-based lesion model-indicating the advantage of the model for use in both hybrid CT images and in simulated CT imaging of the lungs. CONCLUSIONS Results indicated the non-inferiority of this model as compared to previous methods, indicating the utility of the model for use in both hybrid CT images and in simulated CT imaging.
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Affiliation(s)
- Thomas J. Sauer
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Adrian Bejan
- Department of Mechanical Engineering, Duke University, Durham, North Carolina, USA
| | - Paul Segars
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Ehsan Samei
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
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Reichmann J, Verleden SE, Kühnel M, Kamp JC, Werlein C, Neubert L, Müller JH, Bui TQ, Ackermann M, Jonigk D, Salditt T. Human lung virtual histology by multi-scale x-ray phase-contrast computed tomography. Phys Med Biol 2023; 68. [PMID: 37167977 DOI: 10.1088/1361-6560/acd48d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 05/11/2023] [Indexed: 05/13/2023]
Abstract
As the central organ of the respiratory system, the human lung is responsible for supplying oxygen to the blood, which reaches the erythrocytes by diffusion through the alveolar walls and is then distributed throughout the body. By exploiting the difference in electron density detected by a phase shift in soft tissue, high-resolution X-ray phase-contrast computed tomography (XPCT) can resolve biological structures in a sub-μm range, shedding new light on the three-dimensional structure of the lungs, physiological functions and pathological mechanisms.

This work presents both synchrotron and laboratory XPCT results of postmortem tissue from autopsies and biopsies embedded with various preparation protocols such as precision-cut lung slices, cryogenically fixed lung tissue, as well as paraffin and alcohol fixed tissue. The selection of pathological abnormalities includes channel of Lambert, bronchus-associated lymphoid tissue, alveolar capillary dysplasia with misalignment of pulmonary veins. Subsequently, quantification and visualization approaches are presented.

The overall high image quality even of in-house XPCT scans for the case of FFPE biopsies can be exploited for a wide range of pulmonary pathologies and translated to dedicated and optimized instrumentation which could be operated in clinical setting. By using synchrotron radiation, contrast can be further increased to resolve sub-μm sized features down to the sub-cellular level. The results demonstrate that a wide range of preparation protocols including sample mounting in liquids can be used. 

With XPCT, poorly understood 3D structures can be identified in larger volume overview and subsequently studied in more detail at higher resolution. With the full 3D structure, the respective physiological functions of airways or vascular networks, and the different pathophysiologic mechanisms can be elucidated or at least underpinned with structural data. Moreover, synchrotron data can be used to validate laboratory protocols and provide ground truth for standardizing the method.

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Affiliation(s)
- Jakob Reichmann
- University of Göttingen Institute for X-Ray Physics, Friedrich-Hund-Platz 1, Gottingen, Niedersachsen, 37077, GERMANY
| | - Stijn E Verleden
- Antwerp Surgical Training, Anatomy and Research Centre (ASTARC), University of Antwerp, Universiteitsplein 1, Antwerpen, 2000, BELGIUM
| | - Mark Kühnel
- Institute of Pathology, Hannover Medical School, Carl-Neuberg-Straße 1, Hannover, Niedersachsen, 30625, GERMANY
| | - Jan C Kamp
- Biomedical Research in Endstage and Obstructive Lung Disease , German Center for Lung Research, Carl-Neuberg-Str. 1, Hannover, Niedersachsen, 30625, GERMANY
| | - Christopher Werlein
- Institute of Pathology, Hannover Medical School, Carl-Neuberg-Straße 1, Hannover, Niedersachsen, 30625, GERMANY
| | - Lavinia Neubert
- Institute of Pathology, Hannover Medical School, Carl-Neuberg-Straße 1, Hannover, Niedersachsen, 30625, GERMANY
| | - Jan-Hendrik Müller
- University of Göttingen Institute for X-Ray Physics, Friedrich-Hund-Platz 1, Gottingen, Niedersachsen, 37077, GERMANY
| | - Thanh Quynh Bui
- University of Göttingen Institute for X-Ray Physics, Friedrich-Hund-Platz 1, Gottingen, Niedersachsen, 37077, GERMANY
| | - Maximilian Ackermann
- Institute of Pathology and Department of Molecular Pathology, HELIOS University Hospital Wuppertal, Heusnerstraße 40, Wuppertal, Nordrhein-Westfalen, 42283, GERMANY
| | - Danny Jonigk
- RWTH Aachen University Medical Faculty, Pauwelsstraße 30, Aachen, Nordrhein-Westfalen, 52074, GERMANY
| | - Tim Salditt
- University of Göttingen Institute for X-Ray Physics, Friedrich-Hund-Platz 1, Gottingen, Niedersachsen, 37077, GERMANY
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10
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Abstract
ABSTRACT Worldwide, radiographers' radiation protection practices vary. In South Africa, evidence of diagnostic radiographers' suboptimal radiation protection practices has been reported, but the reasons for these practices and suggestions to improve practices were lacking. Therefore, this study explored radiation protection among South African diagnostic radiographers. This study used an explanatory, sequential, mixed-method approach. Data were collected in three phases. Phase I, the quantitative phase, used an online questionnaire and respondents from Phase I interested in participating in Phase II, the qualitative phase, were interviewed, yielding 13 in-depth semi-structured telephone interviews. In Phase III, eight radiography managers co-constructed change strategies to optimize radiation protection in South Africa in two focus group interviews. Radiation protection was suboptimal despite diagnostic radiographers having a good attitude, subjective norm and perceived behavioral control toward radiation protection and optimal radiation protection knowledge. Varying attitudes to radiation protection, lack of resources, and support from radiography management and healthcare teams contributed to suboptimal radiation protection practices. Radiography managers suggested increasing radiation protection awareness, ameliorating the diminished stature of the radiographer in the healthcare team, and increasing the availability of optimal quality resources. South African diagnostic radiographers' radiation protection knowledge was optimal, but the implementation of radiation protection varied and was influenced by multiple factors. A radiation protection culture supported by management is advocated to optimize radiation protection. However, ultimately radiation protection practices are incumbent on the individual radiographers' choice to practice radiation protection.
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Affiliation(s)
- Shantel Lewis
- Department of Medical Imaging and Radiation Sciences, Faculty of Health Sciences, 6306a John Orr Building, Doornfontein, Corner Simert and Biet St., Johannesburg, Gauteng, South Africa
| | - Charlene Downing
- Department of Nursing, Faculty of Health Sciences, University of Johannesburg, Office 6105D, West Wing North, John Orr Building, Doornfontein Campus, Corner Siemert and Biet St., Johannesburg, Gauteng, South Africa
| | - Christopher M. Hayre
- School of Dentistry and Health Sciences, University of Exeter, College of Medicine and Health, Room 1.32, South Cloisters, Devon, 79 Heavitree Rd., Exeter EX1 2LT, United Kingdom
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11
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Gao Y, Huang W, Pratama RH, Gong H, Wang J. Investigation of Needle Motion Profile Effect on Diesel Spray in Near-Nozzle Field. Micromachines (Basel) 2022; 13:1944. [PMID: 36363967 PMCID: PMC9697944 DOI: 10.3390/mi13111944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 10/30/2022] [Accepted: 11/08/2022] [Indexed: 06/16/2023]
Abstract
A variety of needle-motion profiles are used in diesel injectors. However, it is unclear what the underlying mechanism is to determine the needle-motion profiles and how they affect the spray dynamics. It has been of significant interest to examine how the spray dynamics will change if only altering the needle valve opening speed or closing speed while all other parameters are kept the same. The different needle-motion profiles were obtained using a piezo nozzle (Nozzle #P) and a solenoid nozzle (Nozzle #S), which have identical nozzle geometry. By utilizing the X-ray imaging technique, it was observed that the average needle valve speed of Nozzle #P was 51% higher at the opening stage but 17% lower at the closing stage than Nozzle #S. When the needle valve lift is low (approximately 200 μm), the needle valve opening speed has a crucial effect on spray dynamics. The faster needle valve opening of Nozzle #P results in a 42% larger spray spreading angle and 34% lower spray velocity at the downstream field. The spray dynamics may be controllable by properly designing the needle-motion profiles in the scenarios of the low needle lifts. However, when the needle valve is sufficiently open (approximately over 200 μm), almost identical spray characteristics were observed regardless of the needle-motion profiles.
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Affiliation(s)
- Ya Gao
- Advanced Photon Source, Argonne National Laboratory, 9700 S Cass Ave, Lemont, IL 60439, USA
| | - Weidi Huang
- Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology, Namiki 1-2-1, Tsukuba 305-8564, Japan
| | - Raditya Hendra Pratama
- Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology, Namiki 1-2-1, Tsukuba 305-8564, Japan
| | - Huifeng Gong
- Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology, Namiki 1-2-1, Tsukuba 305-8564, Japan
| | - Jin Wang
- Advanced Photon Source, Argonne National Laboratory, 9700 S Cass Ave, Lemont, IL 60439, USA
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12
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Cobos SF, Norley CJ, Pollmann SI, Holdsworth DW. High-dynamic-range micro-CT for nondestructive testing of titanium 3D-printed medical components. J Med Imaging (Bellingham) 2022; 9:044004. [PMID: 35928636 PMCID: PMC9339667 DOI: 10.1117/1.jmi.9.4.044004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 07/18/2022] [Indexed: 08/03/2023] Open
Abstract
Purpose: Industrial microcomputed tomography (micro-CT) scanners are suitable for nondestructive testing (NDT) of metal, 3D-printed medical components. Typically, these scanners are equipped with high-energy sources that require heavy shielding and costly infrastructure to operate safely, making routine NDT of medical components prohibitively expensive. Alternatively, fixed-current, low-cost x-ray units could be implemented to perform CT-based NDT of 3D-printed medical parts in a subset of cases, if there is sufficient x-ray transmission for the CT reconstruction. A lack of signal-caused by areas of high attenuation in two-dimensional-projection images of metal objects-leads to artifacts that can make an image-based NDT unreliable. We present the implementation of a dual-exposure technique devised to extend the dynamic range (DR) of a commercially available CT scanner equipped with a low-cost low-energy (80 kV) x-ray unit, increasing the signal-to-noise ratio of highly attenuated areas for NDT of 3D-printed medical components. Approach: Our high-dynamic-range CT (HDR-CT) technique adequately combines projection images acquired at two exposure levels by modifying the integration times of each protocol. We evaluate the performance and limitations of this HDR-CT technique by imaging a series of titanium-alloy test-samples. One of the test-samples was a resolution and conspicuity phantom designed to assess the improvements in void visualization of the proposed methodology. The other test-samples were four porous cylinders, 17 × 40 mm , with 60%, 70%, 80%, and 90% nominal internal porosities. Results: Our HDR-CT technique adequately combines projection images acquired at two exposure levels by modifying the integration times of each protocol. Our results demonstrate that the 12-bit native DR of the CT scanner was increased to effective values of between 14 and 16 bits. Conclusions: The HDR-CT reconstructions showed improved contrast-to-noise and void conspicuity, when compared with conventional CT scans. This extension of DR has the potential to improve defect visualization during NDT of medium-size, titanium-alloy, 3D-printed medical components.
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Affiliation(s)
- Santiago Fabian Cobos
- University of Western Ontario, Schulich School of Medicine and Dentistry, Department of Medical Biophysics, London, Ontario, Canada
| | - Christopher James Norley
- University of Western Ontario, Robarts Research Institute, Imaging Research Laboratories, London, Ontario, Canada
| | - Steven Ingo Pollmann
- University of Western Ontario, Robarts Research Institute, Imaging Research Laboratories, London, Ontario, Canada
| | - David Wayne Holdsworth
- University of Western Ontario, Schulich School of Medicine and Dentistry, Department of Medical Biophysics, London, Ontario, Canada
- University of Western Ontario, Robarts Research Institute, Imaging Research Laboratories, London, Ontario, Canada
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13
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Shi Z, Josell D, Jefimovs K, Romano L, Moffat TP, Stampanoni M, Schlepütz CM. Fabrication of a fractal pattern device for focus characterizations of X-ray imaging systems by Si deep reactive ion etching and bottom-up Au electroplating. Appl Opt 2022; 61:3850-3854. [PMID: 36256429 PMCID: PMC9979867 DOI: 10.1364/ao.456427] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 04/11/2022] [Indexed: 06/16/2023]
Abstract
Precisely aligned optical components are crucial prerequisites for X-ray tomography at high resolution. We propose a device with a fractal pattern for precise automatic focusing. The device is etched in a Si substrate by deep reactive ion etching and then filled by a self-terminating bottom-up Au electroplating process. The fractal nature of the device produces an X-ray transmission image with globally homogeneous macroscopic visibility and high local contrast for pixel sizes in the range of 0.165 µm to 11 µm, while the high absorption contrast provided between Au and Si enables its use for X-ray energies ranging from 12 keV to 40 keV.
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Affiliation(s)
- Zhitian Shi
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
- Institute for Biomedical Engineering, University and ETH Zürich, Zürich 8092, Switzerland
| | - Daniel Josell
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | | | - Lucia Romano
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
- Institute for Biomedical Engineering, University and ETH Zürich, Zürich 8092, Switzerland
| | - Thomas P. Moffat
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Marco Stampanoni
- Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
- Institute for Biomedical Engineering, University and ETH Zürich, Zürich 8092, Switzerland
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14
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Muhammad K, Ullah H, Khan ZA, Saudagar AKJ, AlTameem A, AlKhathami M, Khan MB, Abul Hasanat MH, Mahmood Malik K, Hijji M, Sajjad M. WEENet: An Intelligent System for Diagnosing COVID-19 and Lung Cancer in IoMT Environments. Front Oncol 2022; 11:811355. [PMID: 35186717 PMCID: PMC8847175 DOI: 10.3389/fonc.2021.811355] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 12/01/2021] [Indexed: 01/09/2023] Open
Abstract
The coronavirus disease 2019 (COVID-19) pandemic has caused a major outbreak around the world with severe impact on health, human lives, and economy globally. One of the crucial steps in fighting COVID-19 is the ability to detect infected patients at early stages and put them under special care. Detecting COVID-19 from radiography images using computational medical imaging method is one of the fastest ways to diagnose the patients. However, early detection with significant results is a major challenge, given the limited available medical imaging data and conflicting performance metrics. Therefore, this work aims to develop a novel deep learning-based computationally efficient medical imaging framework for effective modeling and early diagnosis of COVID-19 from chest x-ray and computed tomography images. The proposed work presents “WEENet” by exploiting efficient convolutional neural network to extract high-level features, followed by classification mechanisms for COVID-19 diagnosis in medical image data. The performance of our method is evaluated on three benchmark medical chest x-ray and computed tomography image datasets using eight evaluation metrics including a novel strategy of cross-corpse evaluation as well as robustness evaluation, and the results are surpassing state-of-the-art methods. The outcome of this work can assist the epidemiologists and healthcare authorities in analyzing the infected medical chest x-ray and computed tomography images, management of the COVID-19 pandemic, bridging the early diagnosis, and treatment gap for Internet of Medical Things environments.
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Affiliation(s)
- Khan Muhammad
- Visual Analytics for Knowledge Laboratory (VIS2KNOW Lab), School of Convergence, College of Computing and Informatics, Sungkyunkwan University, Seoul, South Korea
| | - Hayat Ullah
- Department of Software, Sejong University, Seoul, South Korea
| | | | - Abdul Khader Jilani Saudagar
- Information Systems Department, College of Computer and Information Sciences, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia
| | - Abdullah AlTameem
- Information Systems Department, College of Computer and Information Sciences, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia
| | - Mohammed AlKhathami
- Information Systems Department, College of Computer and Information Sciences, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia
| | - Muhammad Badruddin Khan
- Information Systems Department, College of Computer and Information Sciences, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia
| | - Mozaherul Hoque Abul Hasanat
- Information Systems Department, College of Computer and Information Sciences, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia
| | - Khalid Mahmood Malik
- Department of Computer Science & Engineering, Oakland University, Rochester, MI, United States
| | - Mohammad Hijji
- Faculty of Computers & Information Technology, Computer Science Department, University of Tabuk, Tabuk, Saudi Arabia
| | - Muhammad Sajjad
- Digital Image Processing Laboratory, Islamia College Peshawar, Peshawar, Pakistan.,Color and Visual Computing Lab, Department of Computer Science, Norwegian University of Science and Technology (NTNU), Gjøvik, Norway
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15
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Zhang Z, Dierks H, Lamers N, Sun C, Nováková K, Hetherington C, Scheblykin IG, Wallentin J. Single-Crystalline Perovskite Nanowire Arrays for Stable X-ray Scintillators with Micrometer Spatial Resolution. ACS Appl Nano Mater 2022; 5:881-889. [PMID: 35128340 PMCID: PMC8805114 DOI: 10.1021/acsanm.1c03575] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 12/06/2021] [Indexed: 05/06/2023]
Abstract
X-ray scintillation detectors based on metal halide perovskites have shown excellent light yield, but they mostly target applications with spatial resolution at the tens of micrometers level. Here, we use a one-step solution method to grow arrays of 15-μm-long single-crystalline CsPbBr3 nanowires (NWs) in an AAO (anodized aluminum oxide) membrane template, with nanowire diameters ranging from 30 to 360 nm. The CsPbBr3 nanowires in AAO (CsPbBr3 NW/AAO) show increasing X-ray scintillation efficiency with decreasing nanowire diameter, with a maximum photon yield of ∼5 300 ph/MeV at 30 nm diameter. The CsPbBr3 NW/AAO composites also display high radiation resistance, with a scintillation-intensity decrease of only ∼20-30% after 24 h of X-ray exposure (integrated dose 162 Gyair) and almost no change after ambient storage for 2 months. X-ray images can distinguish line pairs with a spacing of 2 μm for all nanowire diameters, while slanted edge measurements show a spatial resolution of ∼160 lp/mm at modulation transfer function (MTF) = 0.1. The combination of high spatial resolution, radiation stability, and easy fabrication makes these CsPbBr3 NW/AAO scintillators a promising candidate for high-resolution X-ray imaging applications.
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Affiliation(s)
- Zhaojun Zhang
- Synchrotron
Radiation Research and NanoLund, Department of Physics, Lund University, Box 124, Lund 22100, Sweden
| | - Hanna Dierks
- Synchrotron
Radiation Research and NanoLund, Department of Physics, Lund University, Box 124, Lund 22100, Sweden
| | - Nils Lamers
- Synchrotron
Radiation Research and NanoLund, Department of Physics, Lund University, Box 124, Lund 22100, Sweden
| | - Chen Sun
- Chemical
Physics and NanoLund, Department of Chemistry, Lund University, Box 124, Lund 22100, Sweden
| | - Klára Nováková
- Chemical
Physics and NanoLund, Department of Chemistry, Lund University, Box 124, Lund 22100, Sweden
| | - Crispin Hetherington
- Centre
for Analysis and Synthesis and NanoLund, Department of Chemistry, Lund University, Box
124, Lund 22100, Sweden
| | - Ivan G. Scheblykin
- Chemical
Physics and NanoLund, Department of Chemistry, Lund University, Box 124, Lund 22100, Sweden
| | - Jesper Wallentin
- Synchrotron
Radiation Research and NanoLund, Department of Physics, Lund University, Box 124, Lund 22100, Sweden
- E-mail:
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16
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Primidis TG, Wells SG, Soloviev VY, Welsch CP. 3D chest tomosynthesis using a stationary flat panel source array and a stationary detector: a Monte Carlo proof of concept. Biomed Phys Eng Express 2021; 8. [PMID: 34757950 DOI: 10.1088/2057-1976/ac3880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 11/10/2021] [Indexed: 11/12/2022]
Abstract
3D imaging modalities such as computed tomography and digital tomosynthesis typically scan the patient from different angles with a lengthy mechanical movement of a single x-ray tube. Therefore, millions of 3D scans per year require expensive mechanisms to support a heavy x-ray source and have to compensate for machine vibrations and patient movements. However, recent developments in cold-cathode field emission technology allow the creation of compact, stationary arrays of emitters. Adaptix Ltd has developed a novel, low-cost, square array of such emitters and demonstrated 3D digital tomosynthesis of human extremities and small animals. The use of cold-cathode field emitters also makes the system compact and lightweight. This paper presents Monte Carlo simulations of a concept upgrade of the Adaptix system from the current 60 kVp to 90 kVp and 120 kVp which are better suited for chest imaging. Between 90 kVp and 120 kVp, 3D image quality appears insensitive to voltage and at 90 kVp the photon yield is reduced by 40%-50% while effective dose declines by 14%. A square array of emitters can adequately illuminate a subject for tomosynthesis from a shorter source-to-image distance, thereby reducing the required input power, and offsetting the 28%-50% more input power that is required for operation at 90 kVp. This modelling suggests that lightweight, stationary cold-cathode x-ray source arrays could be used for chest tomosynthesis at a lower voltage, with less dose and without sacrificing image quality. This will reduce weight, size and cost, enabling 3D imaging to be brought to the bedside.
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Affiliation(s)
- Thomas G Primidis
- Department of Physics, University of Liverpool, Liverpool, United Kingdom.,The Cockcroft Institute, Sci-Tech Daresbury, Warrington, United Kingdom
| | - Stephen G Wells
- Adaptix Ltd, Oxford University Begbroke Science Park, Oxford, United Kingdom
| | - Vadim Y Soloviev
- Adaptix Ltd, Oxford University Begbroke Science Park, Oxford, United Kingdom
| | - Carsten P Welsch
- Department of Physics, University of Liverpool, Liverpool, United Kingdom.,The Cockcroft Institute, Sci-Tech Daresbury, Warrington, United Kingdom
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17
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Ghammraoui B, Zidan A, Alayoubi A, Zidan A, Glick SJ. Fabrication of microcalcifications for insertion into phantoms used to evaluate x-ray breast imaging systems. Biomed Phys Eng Express 2021; 7. [PMID: 34375962 DOI: 10.1088/2057-1976/ac1c64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 08/10/2021] [Indexed: 11/12/2022]
Abstract
Physical breast phantoms can be used to evaluate x-ray imaging systems such as mammography, digital breast tomosynthesis and dedicated breast computed tomography (bCT). These phantoms typically attempt to mimic x-ray attenuation properties of adipose and fibroglandular tissues within the breast. In order to use these phantoms for task-based objective assessment of image quality, relevant diagnostic features should be modeled within the phantom, such as mass lesions and/or microcalcifications. Evaluating imaging system performance in detecting microcalcifications is of particular interest due to its' clinical significance. Many previously-developed phantoms have used materials that model microcalcifications using unrealistic chemical composition, which do not accurately portray their desired x-ray attenuation and scatter properties. We report here on a new method for developing real microcalcification simulants that can be embedded in breast phantoms. This was achieved in several steps, including cross-linking hydroxyapatite and calcium oxalate powders with a binder called polyvinylpyrrolidone (PVP), and mechanical compression. The fabricated microcalcifications were evaluated by measuring their x-ray attenuation and scatter properties using x-ray spectroscopy and x-ray diffraction systems, respectively, and were demonstrated with x-ray mammography and bCT images. Results suggest that using these microcalcification models will make breast phantoms more realistic for use in evaluating task-based detection performance of the abovementioned breast imaging techniques, and bode well for extending their use to spectral imaging and x-ray coherent scatter computed tomography.
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Affiliation(s)
- Bahaa Ghammraoui
- Division of Imaging, Diagnostics, and Software Reliability, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993, United States of America
| | - Ahmed Zidan
- Division of Product Quality and Research, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, United States of America
| | - Alaadin Alayoubi
- Division of Product Quality and Research, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, United States of America
| | - Aser Zidan
- Division of Product Quality and Research, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, United States of America.,University of Maryland, Baltimore County, Baltimore, Maryland, United States of America
| | - Stephen J Glick
- Division of Imaging, Diagnostics, and Software Reliability, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993, United States of America
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18
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Primidis TG, Soloviev VY, Welsch CP. Accuracy of the independent atom approximation in digital tomosynthesis Monte Carlo simulations. Biomed Phys Eng Express 2021; 7. [PMID: 34369894 DOI: 10.1088/2057-1976/ac1987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 07/30/2021] [Indexed: 11/11/2022]
Abstract
Monte Carlo (MC) codes serve as the gold standard simulation tool during design and optimisation of x-ray imaging systems. Such simulations often model Rayleigh scattering based on the Independent Atom Approximation Model (IAM). This model neglects the low range molecular interference (MI) effects of non-crystalline materials such as human tissues. Previous work has found discrepancies in the simulated images of planar x-ray images between IAM and MI models. However, insignificant differences were found for computed tomography (CT) reconstructions. In this work we present Geant4 MC simulations of a flat panel source digital tomosynthesis (DT) system for human extremities. Results show that with a 1:9 scatter to primary ratio (SPR) in the x-ray projections, the DT reconstructions are insensitive to the differences of the IAM and MI models. Therefore, MC codes that use the IAM model are sufficient for the study of DT systems. That is because DT algorithms have a larger effect on image quality than the few percent change in the noise due to a physical model and noise suppression methods make this change even less important. Dependency of this conclusion on SPR must be considered in other DT modalities where SPR might be larger.
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Affiliation(s)
- Thomas G Primidis
- Department of Physics, University of Liverpool, Liverpool, United Kingdom.,The Cockcroft Institute, Sci-Tech Daresbury, Warrington, United Kingdom
| | - Vadim Y Soloviev
- Adaptix Ltd, Oxford University Begbroke Science Park, Oxford, United Kingdom
| | - Carsten P Welsch
- Department of Physics, University of Liverpool, Liverpool, United Kingdom.,The Cockcroft Institute, Sci-Tech Daresbury, Warrington, United Kingdom
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19
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Olivo A. Edge-illumination x-ray phase-contrast imaging. J Phys Condens Matter 2021; 33:363002. [PMID: 34167096 PMCID: PMC8276004 DOI: 10.1088/1361-648x/ac0e6e] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 06/07/2021] [Accepted: 06/24/2021] [Indexed: 05/08/2023]
Abstract
Although early demonstration dates back to the mid-sixties, x-ray phase-contrast imaging (XPCI) became hugely popular in the mid-90s, thanks to the advent of 3rd generation synchrotron facilities. Its ability to reveal object features that had so far been considered invisible to x-rays immediately suggested great potential for applications across the life and the physical sciences, and an increasing number of groups worldwide started experimenting with it. At that time, it looked like a synchrotron facility was strictly necessary to perform XPCI with some degree of efficiency-the only alternative being micro-focal sources, the limited flux of which imposed excessively long exposure times. However, new approaches emerged in the mid-00s that overcame this limitation, and allowed XPCI implementations with conventional, non-micro-focal x-ray sources. One of these approaches showing particular promise for 'real-world' applications is edge-illumination XPCI: this article describes the key steps in its evolution in the context of contemporary developments in XPCI research, and presents its current state-of-the-art, especially in terms of transition towards practical applications.
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Affiliation(s)
- Alessandro Olivo
- Department of Medical Physics and Biomedical Engineering, UCL, London, United Kingdom
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20
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Wilson-Stewart K, Fontanarosa D, Malacova E, Gett S, Kruger A, Trapp JV. Occupational and Patient Radiation Dose and Quality Implications of Femoral Access Imaging During Coronary Angiography. J Multidiscip Healthc 2021; 14:1807-1818. [PMID: 34285499 PMCID: PMC8286066 DOI: 10.2147/jmdh.s316135] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 06/16/2021] [Indexed: 01/10/2023] Open
Abstract
Purpose Cardiologists often perform angiography of the common femoral artery (CFA) access site to evaluate whether the anatomy is suitable for deployment of a vascular closure device or to assess whether iatrogenic vessel damage has occurred. The choice of acquisition mode has radiation dose implications. The objective of this study was to investigate the influence of the selected type of CFA x-ray imaging mode (fluoro save, cine acquisition and digital subtraction angiography (DSA)) and tube angle on patient and staff dose during coronary angiography. Materials and Methods Assessment of image quality for the different modes was performed to determine whether lower dose modes provide images of sufficient clinical quality to be routinely employed. Radiation dose levels for the patients (n=782), cardiologists (n=17), scrub nurses (n=27) and scout nurses (n=32) were measured in a prospective single-centre study between February 2017 and August 2019. Three Philips angiographic units and DoseAware dose monitoring systems were used. Results Among the acquisition modes, fluoro save provided acceptable diagnostic quality for visualizing femoral access points and diagnosing pathology in 99% of cases. Average patient dose area product (DAP) was 83.95, 742.50, and 3363.41mGy2 and average patient air kerma (AK) was 0.87, 8.44, and 18.61mGy for fluoro save, cine, and DSA acquisitions, respectively. The use of higher dose imaging modes, imaging in the contralateral view and utilizing steeper TA was associated with a higher patient dose. Due to staff dose being highly correlated with DAP and AK, it was difficult to observe any association between staff dose and CFA imaging mode. However, this does not discount a potential increase in occupational dose due to the use of cine angiography or digital subtraction angiography during CFA imaging. Conclusion DSA of the CFA should be avoided during transfemoral coronary angiography unless critical to diagnostic analysis. It is recommended that fluoroscopic operators consider utilizing lower dose modes in the ipsilateral orientation ≤32° TA to reduce the risk of patient and staff radiation exposure. ![]()
Point your SmartPhone at the code above. If you have a QR code reader, the video abstract will appear. Or use: https://youtu.be/fkaiBXXpPsE
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Affiliation(s)
- Kelly Wilson-Stewart
- School of Chemistry and Physics, Faculty of Science, Queensland University of Technology, Brisbane, QLD, 4000, Australia.,Cardiiovascular Suites, Greenslopes Private Hospital, Brisbane, QLD, 4120, Australia
| | - Davide Fontanarosa
- School of Clinical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD, 4000, Australia.,Centre for Biomedical Technologies (CBT), Queensland University of Technology, Brisbane, QLD, 4000, Australia
| | - Eva Malacova
- School of Clinical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD, 4000, Australia.,QMIR Berghofer Medical Research Institute, Herston, QLD, 4006, Australia
| | - Steven Gett
- Cardiiovascular Suites, Greenslopes Private Hospital, Brisbane, QLD, 4120, Australia
| | - Allan Kruger
- Cardiiovascular Suites, Greenslopes Private Hospital, Brisbane, QLD, 4120, Australia.,Department of Vascular Surgery, Royal Brisbane and Women's Hospital, Herston, QLD, 4029, Australia
| | - Jamie V Trapp
- School of Chemistry and Physics, Faculty of Science, Queensland University of Technology, Brisbane, QLD, 4000, Australia
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21
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Zhong Z, Zhang P, Duan H, Yang H, Li Q, He F. A Comparison Between X-ray Imaging and an Innovative Computer-aided Design Method Based on Weightbearing CT Scan Images for Assessing Hallux Valgus. J Foot Ankle Surg 2021; 60:6-10. [PMID: 32253154 DOI: 10.1053/j.jfas.2018.12.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 12/25/2018] [Accepted: 12/31/2018] [Indexed: 02/03/2023]
Abstract
With the development of recent technology, radiographs can be saved digitally, and angular measurements can be processed using various software packages. We developed an innovative computer-aided design method with Materialize Interactive Medical Image Control System software to measure hallux valgus angle (HVA), the intermetatarsal angle (IMA), and the distal metatarsal articular angle (DMAA) and assessed its concordance with traditional X-ray imaging methods. All measurements were carried out on 42 feet from 26 adult patients diagnosed with hallux valgus who were prospectively selected from July 2016 to April 2018. Standing X-ray radiograph and weightbearing computed tomography scans were conducted on all patients, and HVA, IMA, and DMAA were generated using both a traditional X-ray method and our innovative method. Two different observers assessed measurements for each patient. Finally, statistical analyses were conducted to assess the reliability of the measurements. Both X-ray imaging and our innovative method had strong interobserver and test-retest reliability. The ICC of X-ray imaging was 0.945, p < .001, and the ICC of the innovative method was 0.915, p < .001. There was no statistical difference between the 2 methods for HVA and IMA measurements (p > .05); however, a difference was detected for DMAA (p < .05). Bland-Altman analyses demonstrated a high degree of agreement between the 2 methods for HVA and IMA, but a significant difference for DMAA. From the results, we concluded that our innovative computer-aided design method is a feasible, reliable way to quantitatively assess HVA, IMA, and DMAA, and it is likely more accurate for measuring DMAA.
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Affiliation(s)
- Zongyu Zhong
- Department of Orthopedics, the First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Peng Zhang
- Xiangyang Central Hospital, Affiliated Hospital Of Hubei University of Arts and Science
| | - Hao Duan
- Department of Orthopedics, the First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Hao Yang
- Department of Orthopedics, the First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Qing Li
- Department of Orthopedics, the First Affiliated Hospital of Kunming Medical University, Kunming, China
| | - Fei He
- Department of Orthopedics, the First Affiliated Hospital of Kunming Medical University, Kunming, China.
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22
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Maruyama S, Saito H, Shimosegawa M. Characterization of anti-scatter grids via a modulation transfer function improvement factor using an edge device. Biomed Phys Eng Express 2021; 7. [PMID: 33906178 DOI: 10.1088/2057-1976/abfc2f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 04/27/2021] [Indexed: 11/12/2022]
Abstract
In optimizing the imaging conditions, changes in image quality due to scattered radiation are important evaluation targets. This study focuses on the evaluation of the image quality improvement characteristics obtained using anti-scatter grids in digital x-ray imaging, and proposes a frequency-dependent modulation transfer function (MTF) improvement factor,MIFG(u),as a new evaluation index. Accordingly, the purpose of this study is to clarify the validity and the usefulness of this proposed index in the performance evaluation of grids. The proposedMIFG(u)method is applied to evaluate several types of grids with different grid densities and ratios, and the characteristics of grids exhibiting different performances are examined. The proposed index is calculated based on the MTF measurement by using an edge test device. The results show thatMIFG(u)changed according to grid type and scatter conditions. In particular, a remarkable difference was observed in the high scatter condition compared with the low condition.MIFG(u)in the vertical direction with regards to the absorbing strips shows a peak at 0.2-0.5 cycles/mm and be a constant value from approximately 1 cycle/mm; whileMIFG(u)in the parallel direction is a constant value with respect to changes in spatial frequency. It is shown thatMIFG(u)could be used to accurately describe the characteristics of a grid under different imaging conditions. We believe that the use of the proposed index could expand the options for optimizing imaging conditions when using grids.
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Affiliation(s)
- Sho Maruyama
- School of Radiological Sciences, Faculty of Health Science, Gunma Paz University, Gunma, Japan.,Graduate School of Radiological Technology, Gunma Prefectural College of Health Sciences, Gunma, Japan
| | - Hiroki Saito
- School of Radiological Sciences, Faculty of Health Science, Gunma Paz University, Gunma, Japan
| | - Masayuki Shimosegawa
- Graduate School of Radiological Technology, Gunma Prefectural College of Health Sciences, Gunma, Japan
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23
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Lun MC, Cong W, Arifuzzaman M, Ranasinghe M, Bhattacharya S, Anker JN, Wang G, Li C. Focused x-ray luminescence imaging system for small animals based on a rotary gantry. J Biomed Opt 2021; 26:JBO-200417R. [PMID: 33738992 PMCID: PMC7970409 DOI: 10.1117/1.jbo.26.3.036004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 02/24/2021] [Indexed: 06/12/2023]
Abstract
SIGNIFICANCE The ability to detect and localize specific molecules through tissue is important for elucidating the molecular basis of disease and treatment. Unfortunately, most current molecular imaging tools in tissue either lack high spatial resolution (e.g., diffuse optical fluorescence tomography or positron emission tomography) or lack molecular sensitivity (e.g., micro-computed tomography, μCT). X-ray luminescence imaging emerged about 10 years ago to address this issue by combining the molecular sensitivity of optical probes with the high spatial resolution of x-ray imaging through tissue. In particular, x-ray luminescence computed tomography (XLCT) has been demonstrated as a powerful technique for the high-resolution imaging of deeply embedded contrast agents in three dimensions (3D) for small-animal imaging. AIM To facilitate the translation of XLCT for small-animal imaging, we have designed and built a small-animal dedicated focused x-ray luminescence tomography (FXLT) scanner with a μCT scanner, synthesized bright and biocompatible nanophosphors as contrast agents, and have developed a deep-learning-based reconstruction algorithm. APPROACH The proposed FXLT imaging system was designed using computer-aided design software and built according to specifications. NaGdF4 nanophosphors doped with europium or terbium were synthesized with a silica shell for increased biocompatibility and functionalized with biotin. A deep-learning-based XLCT image reconstruction was also developed based on the residual neural network as a data synthesis method of projection views from few-view data to enhance the reconstructed image quality. RESULTS We have built the FXLT scanner for small-animal imaging based on a rotational gantry. With all major imaging components mounted, the motor controlling the gantry can be used to rotate the system with a high accuracy. The synthesized nanophosphors displayed distinct x-ray luminescence emission, which enables multi-color imaging, and has successfully been bound to streptavidin-coated substrates. Lastly, numerical simulations using the proposed deep-learning-based reconstruction algorithm has demonstrated a clear enhancement in the reconstructed image quality. CONCLUSIONS The designed FXLT scanner, synthesized nanophosphors, and deep-learning-based reconstruction algorithm show great potential for the high-resolution molecular imaging of small animals.
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Affiliation(s)
- Michael C. Lun
- University of California, Merced, Department of Bioengineering, Merced, California, United States
| | - Wenxiang Cong
- Rensselaer Polytechnic Institute, Biomedical Imaging Center, Center for Biotechnology and Interdisciplinary Studies, Department of Biomedical Engineering, Troy, New York, United States
| | - Mohammad Arifuzzaman
- Clemson University, Department of Chemistry, Clemson, South Carolina, United States
| | - Meenakshi Ranasinghe
- Clemson University, Department of Chemistry, Clemson, South Carolina, United States
| | - Sriparna Bhattacharya
- Clemson University, Clemson Nanomaterials Institute, Department of Physics and Astronomy, Clemson, South Carolina, United States
| | - Jeffrey N. Anker
- Clemson University, Department of Chemistry, Clemson, South Carolina, United States
- Clemson University, Institute of Environmental Toxicology, Center for Optical Materials Science and Engineering Technology, Department of Bioengineering, Clemson, South Carolina, United States
| | - Ge Wang
- Rensselaer Polytechnic Institute, Biomedical Imaging Center, Center for Biotechnology and Interdisciplinary Studies, Department of Biomedical Engineering, Troy, New York, United States
| | - Changqing Li
- University of California, Merced, Department of Bioengineering, Merced, California, United States
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24
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Acciavatti RJ, Cohen EA, Maghsoudi OH, Gastounioti A, Pantalone L, Hsieh MK, Barufaldi B, Bakic PR, Chen J, Conant EF, Kontos D, Maidment ADA. Calculation of Radiomic Features to Validate the Textural Realism of Physical Anthropomorphic Phantoms for Digital Mammography. Proc SPIE Int Soc Opt Eng 2020; 11513:1151309. [PMID: 37818096 PMCID: PMC10564085 DOI: 10.1117/12.2564363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
In this paper, radiomic features are used to validate the textural realism of two anthropomorphic phantoms for digital mammography. One phantom was based off a computational breast model; it was 3D printed by CIRS (Computerized Imaging Reference Systems, Inc., Norfolk, VA) under license from the University of Pennsylvania. We investigate how the textural realism of this phantom compares against a phantom derived from an actual patient's mammogram ("Rachel", Gammex 169, Madison, WI). Images of each phantom were acquired at three kV in 1 kV increments using auto-time technique settings. Acquisitions at each technique setting were repeated twice, resulting in six images per phantom. In the raw ("FOR PROCESSING") images, 341 features were calculated; i.e., gray-level histogram, co-occurrence, run length, fractal dimension, Gabor Wavelet, local binary pattern, Laws, and co-occurrence Laws features. Features were also calculated in a negative screening population. For each feature, the middle 95% of the clinical distribution was used to evaluate the textural realism of each phantom. A feature was considered realistic if all six measurements in the phantom were within the middle 95% of the clinical distribution. Otherwise, a feature was considered unrealistic. More features were actually found to be realistic by this definition in the CIRS phantom (305 out of 341 features or 89.44%) than in the phantom derived from a specific patient's mammogram (261 out of 341 features or 76.54%). We conclude that the texture is realistic overall in both phantoms.
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Affiliation(s)
- Raymond J Acciavatti
- University of Pennsylvania, Department of Radiology, 3400 Spruce Street, Philadelphia PA 19104
| | - Eric A Cohen
- University of Pennsylvania, Department of Radiology, 3400 Spruce Street, Philadelphia PA 19104
| | - Omid Haji Maghsoudi
- University of Pennsylvania, Department of Radiology, 3400 Spruce Street, Philadelphia PA 19104
| | - Aimilia Gastounioti
- University of Pennsylvania, Department of Radiology, 3400 Spruce Street, Philadelphia PA 19104
| | - Lauren Pantalone
- University of Pennsylvania, Department of Radiology, 3400 Spruce Street, Philadelphia PA 19104
| | - Meng-Kang Hsieh
- University of Pennsylvania, Department of Radiology, 3400 Spruce Street, Philadelphia PA 19104
| | - Bruno Barufaldi
- University of Pennsylvania, Department of Radiology, 3400 Spruce Street, Philadelphia PA 19104
| | - Predrag R Bakic
- University of Pennsylvania, Department of Radiology, 3400 Spruce Street, Philadelphia PA 19104
| | - Jinbo Chen
- University of Pennsylvania, Department of Epidemiology, Biostatistics, & Informatics, 423 Guardian Drive, Philadelphia, PA 19104
| | - Emily F Conant
- University of Pennsylvania, Department of Radiology, 3400 Spruce Street, Philadelphia PA 19104
| | - Despina Kontos
- University of Pennsylvania, Department of Radiology, 3400 Spruce Street, Philadelphia PA 19104
| | - Andrew D A Maidment
- University of Pennsylvania, Department of Radiology, 3400 Spruce Street, Philadelphia PA 19104
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25
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Hernandez AM, Abbey CK, Ghazi P, Burkett G, Boone JM. Effects of kV, filtration, dose, and object size on soft tissue and iodine contrast in dedicated breast CT. Med Phys 2020; 47:2869-2880. [PMID: 32233091 DOI: 10.1002/mp.14159] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/30/2019] [Accepted: 03/13/2020] [Indexed: 01/07/2023] Open
Abstract
PURPOSE Clinical use of dedicated breast computed tomography (bCT) requires relatively short scan times necessitating systems with high frame rates. This in turn impacts the x-ray tube operating range. We characterize the effects of tube voltage, beam filtration, dose, and object size on contrast and noise properties related to soft tissue and iodine contrast agents as a way to optimize imaging protocols for soft tissue and iodine contrast at high frame rates. METHODS This study design uses the signal-difference-to-noise ratio (SDNR), noise-equivalent quanta (NEQ), and detectability (d´) as measures of imaging performance for a prototype breast CT scanner that utilizes a pulsed x-ray tube (with a 4 ms pulse width) at 43.5 fps acquisition rate. We assess a range of kV, filtration, breast phantom size, and mean glandular dose (MGD). Performance measures are estimated from images of adipose-equivalent breast phantoms machined to have a representative size and shape of small, medium, and large breasts. Water (glandular tissue equivalent) and iodine contrast (5 mg/ml) were used to fill two cylindrical wells in the phantoms. RESULTS Air kerma levels required for obtaining an MGD of 6 mGy ranged from 7.1 to 9.1 mGy and are reported across all kV, filtration, and breast phantom sizes. However, at 50 kV, the thick filters (0.3 mm of Cu or Gd) exceeded the maximum available mA of the x-ray generator, and hence, these conditions were excluded from subsequent analysis. There was a strong positive association between measurements of SDNR and d' (R2 > 0.97) within the range of parameters investigated in this work. A significant decrease in soft tissue SDNR was observed for increasing phantom size and increasing kV with a maximum SDNR at 50 kV with 0.2 mm Cu or 0.2 mm Gd filtration. For iodine contrast SDNR, a significant decrease was observed with increasing phantom size, but a decrease in SDNR for increasing kV was only observed for 70 kV (50 and 60 kV were not significantly different). Thicker Gd filtration (0.3 mm Gd) resulted in a significant increase in iodine SDNR and decrease in soft tissue SDNR but requires significantly more tube current to deliver the same MGD. CONCLUSIONS The choice of 60 kV with 0.2 mm Gd filtration provides a good trade-off for maximizing both soft tissue and iodine contrast. This scanning technique takes advantage of the ~50 keV Gd k-edge to produce contrast and can be achieved within operating range of the x-ray generator used in this work. Imaging at 60 kV allows for a greater range in dose delivered to the large breast sizes when uniform image quality is desired across all breast sizes. While imaging performance metrics (i.e., detectability index and SDNR) were shown to be strongly correlated, the methodologies presented in this work for the estimation of NEQ (and subsequently d') provides a meaningful description of the spatial resolution and noise characteristics of this prototype bCT system across a range of beam quality, dose, and object sizes.
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Affiliation(s)
- Andrew M Hernandez
- Department of Radiology, University of California Davis, Sacramento, 95817, CA, USA
| | - Craig K Abbey
- Department of Psychological & Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | | | - George Burkett
- Department of Radiology, University of California Davis, Sacramento, 95817, CA, USA
| | - John M Boone
- Department of Radiology, University of California Davis, Sacramento, 95817, CA, USA.,Department of Biomedical Engineering, University of California Davis, Sacramento, CA, 95817, USA
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26
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Abstract
Talbot-Lau interferometry (TLI) provides additional contrast modes for x-ray imaging that are complementary to conventional absorption radiography. TLI is particularly interesting because it is one of the few practical methods for realizing phase contrast with x-rays that is compatible with large-spot high power x-ray sources. A novel micro array anode structured target (MAAST) x-ray source offers several advantages for TLI over the conventional combination of an extended x-ray source coupled with an absorption grating including higher flux and larger field of view, and these advantages become more pronounced for x-ray energies in excess of 30 keV. A Monte Carlo simulation was performed to determine the optimal parameters for a MAAST source for use with TLI. It was found that the both spatial distribution of x-ray production and the number of x-ray produced in the MAAST have a strong dependence on the incidence angle of the electron beam.
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Affiliation(s)
- Guibin Zan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, People's Republic of China. Sigray, Inc. 5750 Imhoff Drive, Concord, CA 94520, United States of America. Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, United States of America
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27
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Lun MC, Cong W, Arifuzzaman M, Ranasinghe M, Bhattacharya S, Anker J, Wang G, Li C. X-ray luminescence imaging for small animals. Proc SPIE Int Soc Opt Eng 2020; 11224:112240F. [PMID: 33574637 PMCID: PMC7875188 DOI: 10.1117/12.2544601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
X-ray luminescence imaging emerged for about a decade and combines both the high spatial resolution of x-ray imaging with the high measurement sensitivity of optical imaging, which could result in a great molecular imaging tool for small animals. So far, there are two types of x-ray luminescence computed tomography (XLCT) imaging. One uses a pencil beam x-ray for high spatial resolution at a cost of longer measurement time. The other uses cone beam x-ray to cover the whole mouse to obtain XLCT images at a very short time but with a compromised spatial resolution. Here we review these two methods in this paper and highlight the synthesized nanophosphors by different research groups. We are building a focused x-ray luminescence tomography (FXLT) imaging system, developing a machine-learning based FXLT reconstruction algorithm, and synthesizing nanophosphors with different emission wavelengths. In this paper, we will report our current progress from these three aspects. Briefly, we mount all main components, including the focused x-ray tube, the fiber detector, and the x-ray tube and x-ray detector for a microCT system, on a rotary which is a heavy-duty ring track. A microCT scan will be performed before FXLT scan. For a FXLT scan, we will have four PMTs to measure four fiber detectors at two different wavelengths simultaneously for each linear scan position. We expect the spatial resolution of the FXLT imaging will be around 100 micrometers and a limit of detection of approximately 2 μg/mL (for Gd2O2S:Eu).
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Affiliation(s)
- Michael C Lun
- Department of Bioengineering, University of California, Merced, Merced, CA 95343, USA
| | - Wenxiang Cong
- Department of Biomedical Engineering, Biomedical Imaging Center, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Md. Arifuzzaman
- Department of Chemistry, Clemson University, Clemson, SC 29634, USA
| | | | - Sriparna Bhattacharya
- Clemson Nanomaterials Institute, Department of Physics & Astronomy, Clemson University, Clemson, SC 29634, USA
| | - Jeffery Anker
- Department of Chemistry, Clemson University, Clemson, SC 29634, USA
- Department of Bioengineering, Center for Optical Materials Science and Engineering Technology (COMSET), and Institute of Environment Toxicology (CU-ENTOX), Clemson University, Clemson, SC 29634, USA
| | - Ge Wang
- Department of Biomedical Engineering, Biomedical Imaging Center, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Changqing Li
- Department of Bioengineering, University of California, Merced, Merced, CA 95343, USA
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28
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Abstract
High-resolution imaging modalities play a critical role for advancing biomedical sciences. Recently, x-ray luminescence computed tomography (XLCT) imaging was introduced as a hybrid molecular imaging modality that combines the high-spatial resolution of x-ray imaging and molecular sensitivity of optical imaging. The narrow x-ray beam based XLCT imaging has been demonstrated to achieve high spatial resolution, even at depth, with great molecular sensitivity. Using a focused x-ray beam as the excitation source, orders of magnitude of increased sensitivity has been verified compared with previous methods with a collimated x-ray beam. In this work, we demonstrate the high-spatial resolution capabilities of our focused x-ray beam based XLCT imaging system by scanning two sets of targets, differing in the target size, embedded inside of two tissue-mimicking cylindrical phantoms. Gd2O2S:Eu3+ targets of 200 µm and 150 µm diameters were created and embedded with the same edge-to-edge distances as their diameters respectively. We scanned and reconstructed a single transverse section and successfully demonstrated that a focused x-ray beam with an average dual-cone size of 125 µm could separate the targets in both phantoms with good shape and location accuracy. We have also improved the current XLCT imaging system to make it feasible for fast three-dimensional XLCT scanning.
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Affiliation(s)
- Michael C. Lun
- Department of Bioengineering, University of California, Merced, Merced, CA 95343, USA
| | - Changqing Li
- Department of Bioengineering, University of California, Merced, Merced, CA 95343, USA
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29
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Havariyoun G, Vittoria FA, Hagen CK, Basta D, Kallon GK, Endrizzi M, Massimi L, Munro P, Hawker S, Smit B, Astolfo A, Larkin OJ, Waltham RM, Shah Z, Duffy SW, Nelan RL, Peel A, Suaris T, Jones JL, Haig IG, Bate D, Olivo A. A compact system for intraoperative specimen imaging based on edge illumination x-ray phase contrast. Phys Med Biol 2019; 64:235005. [PMID: 31569079 PMCID: PMC7655119 DOI: 10.1088/1361-6560/ab4912] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 09/09/2019] [Accepted: 09/30/2019] [Indexed: 12/03/2022]
Abstract
A significant number of patients receiving breast-conserving surgery (BCS) for invasive carcinoma and ductal carcinoma in situ (DCIS) may need reoperation following tumor-positive margins from final histopathology tests. All current intraoperative margin assessment modalities have specific limitations. As a first step towards the development of a compact system for intraoperative specimen imaging based on edge illumination x-ray phase contrast, we prove that the system's dimensions can be reduced without affecting imaging performance. We analysed the variation in noise and contrast to noise ratio (CNR) with decreasing system length using the edge illumination x-ray phase contrast imaging setup. Two-(planar) and three-(computed tomography (CT)) dimensional imaging acquisitions of custom phantoms and a breast tissue specimen were made. Dedicated phase retrieval algorithms were used to separate refraction and absorption signals. A 'single-shot' retrieval method was also used, to retrieve thickness map images, due to its simple acquisition procedure and reduced acquisition times. Experimental results were compared to numerical simulations where appropriate. The relative contribution of dark noise signal in integrating detectors is significant for low photon count statistics acquisitions. Under constant exposure factors and magnification, a more compact system provides an increase in CNR. Superior CNR results were obtained for refraction and thickness map images when compared to absorption images. Results indicate that the 'single-shot' acquisition method is preferable for a compact CT intraoperative specimen scanner; it allows for shorter acquisition times and its combination of the absorption and refraction signals ultimately leads to a higher contrast. The first CT images of a breast specimen acquired with the compact system provided promising results when compared to those of the longer length system.
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Affiliation(s)
- Glafkos Havariyoun
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
- Author to whom correspondence should be
addressed
| | - Fabio A Vittoria
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
- Current address: ENEA- Radiation Protection Institue, 4 Via
Martiri di Monte Sole, 40129 Bologna, Italy
| | - Charlotte K Hagen
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
| | - Dario Basta
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
| | - Gibril K Kallon
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
| | - Marco Endrizzi
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
| | - Lorenzo Massimi
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
| | - Peter Munro
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
| | - Sam Hawker
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - Bennie Smit
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - Alberto Astolfo
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - Oliver J Larkin
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - Richard M Waltham
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - Zoheb Shah
- Barts and the London School of Medicine and
Dentistry, Queen Mary University of
London, Newark St, London E1 2AT, United
Kingdom
| | - Stephen W Duffy
- Barts and the London School of Medicine and
Dentistry, Queen Mary University of
London, Newark St, London E1 2AT, United
Kingdom
| | - Rachel L Nelan
- Barts and the London School of Medicine and
Dentistry, Queen Mary University of
London, Newark St, London E1 2AT, United
Kingdom
| | - Anthony Peel
- St Bartholomew’s Hospital, Barts Health NHS Trust, West Smithfields,
London EC1A 7BE, United Kingdom
| | - Tamara Suaris
- St Bartholomew’s Hospital, Barts Health NHS Trust, West Smithfields,
London EC1A 7BE, United Kingdom
| | - J Louise Jones
- Barts and the London School of Medicine and
Dentistry, Queen Mary University of
London, Newark St, London E1 2AT, United
Kingdom
- St Bartholomew’s Hospital, Barts Health NHS Trust, West Smithfields,
London EC1A 7BE, United Kingdom
| | - Ian G Haig
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - David Bate
- Nikon X-Tek Systems, Tring Business Centre, Icknield Way,
Tring, Hertfordshire, HP23 4JX, United Kingdom
| | - Alessandro Olivo
- Department of Medical Physics and
Bioengineering, University College
London, WC1E 6BT, United Kingdom
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30
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Naqvi STS, Batool SW, Rizvi SAH, Farhan K. Awareness of Hazards of X-Ray Imaging and Perception Regarding Necessary Safety Measures to be Taken During X-Ray Imaging Procedures Among Patients in Public Sector Tertiary Hospitals of Karachi, Pakistan. Cureus 2019; 11:e4756. [PMID: 31367492 PMCID: PMC6666880 DOI: 10.7759/cureus.4756] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Background X-ray imaging is a common procedure performed on a regular basis for diagnostic purposes all over the world. The use of X-rays is increasing rapidly with the introduction of new radiation-oriented therapeutic practices. Although it carries significant diagnostic benefits, extensive exposure to X-ray imaging has been shown to be associated with multiple dose-dependent health risks. Awareness and knowledge among patients regarding the effects of X-ray imaging, therefore, becomes important. Through this study, we aimed to assess the knowledge and awareness of the hazards of X-ray imaging among different groups of patients visiting two of the public sector tertiary hospitals in Karachi, Pakistan. We also aimed to evaluate the necessary safety measures undertaken during X-ray imaging in these hospitals, and the perception of patients regarding the importance of these measures. Materials and methods A cross-sectional study was conducted in October and November 2018 at two well-known public sector tertiary care hospitals, Dr. Ruth KM Pfau Civil Hospital, Karachi and Jinnah Postgraduate Medical Centre, Karachi. A non-probability convenience sampling technique was adapted to recruit 200 participants for the study. A pretested questionnaire was used to assess the knowledge of radiation among patients and their perception regarding the necessary safety measures required to be undertaken during the X-ray imaging procedure. Data were entered and analyzed using the IBM Statistical Package for the Social Sciences 17.0 (IBM Corp., New York, USA). Frequencies were calculated for individual variables. Chi-square test was employed to measure the relationship between categorical variables. A p-value of <0.05 was considered to be significant. Results Out of 200 participants, 58% knew what radiation was, 42% did not. The relationship between the level of education of patients and the awareness of the term 'radiation' was found to be statistically significant (p-value = 0.003). Television was the most common source of information (65.5%). One participant (0.5%) thought that it was possible for X-ray imaging to cause cancer. Similarly, only one participant (0.5%) thought that it could cause decreased fertility, five participants (2.5%) thought it could cause burns, seven (3.5%) thought it could cause cataract, and 20 (10%) were of the view that anemia could be caused. The majority of the participants (80.5%) thought that a lead sheet was important during the X-ray procedure for safety and protection. Most participants (71.5%) said that they were never provided with any such lead sheets. When asked if the participants requested for a lead sheet if not provided, the majority (71%) denied requesting for it. On analyzing, we found that a higher percentage of uneducated participants denied requesting a sheet compared to the educated ones. The relationship between the level of education and the choice of requesting for a lead sheet was found to be statistically significant (p-value =0.012). Conclusions The patients visiting the public sector tertiary care hospitals of Karachi seem to lack the knowledge and awareness regarding the hazards of ionizing radiations and the necessary safety measures required to be undertaken during X-ray imaging. More awareness programs should be conducted to increase the level of patients' awareness to protect them from unnecessary health risks.
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Affiliation(s)
- S Tahira S Naqvi
- Internal Medicine, Jinnah Medical and Dental College, Karachi, PAK
| | - Syeda Warda Batool
- Internal Medicine, Civil Hospital Karachi, Dow University of Health Sciences, Karachi, PAK
| | | | - Kinaan Farhan
- Internal Medicine, Jinnah Medical and Dental College, Karachi, PAK
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Ji X, Feng M, Zhang R, Chen GH, Li K. An experimental method to directly measure DQE[Formula: see text] at k = 0 for 2D x-ray imaging systems. Phys Med Biol 2019; 64:075013-75013. [PMID: 30884472 PMCID: PMC6511402 DOI: 10.1088/1361-6560/ab10a2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The zero-frequency detective quantum efficiency (DQE), viz., DQE0, is defined as the ratio between output and input squared signal-to-noise ratio of an imaging system. In 1963, R. Shaw applied Fourier analysis to generalize DQE0 to the frequency-dependent DQE, i.e. DQE[Formula: see text]. Under conditions specified by Shaw, DQE[Formula: see text] is the same as DQE0 at k = 0. The experimental measurement of DQE[Formula: see text] involves the measurement of system modulation transfer function (MTF) and noise power spectrum (NPS). Although the measurement of MTF is straightforward, the experimental measurements of NPS[Formula: see text] encountered several challenges. As a result, some experimental methods may yield a nonphysical NPS value at k = 0, which makes the measured DQE(k)| k=0 deviate from the true zero-frequency DQE. This work presents new results from three aspects: 1) system drift is a significant error source when a large number of independent image acquisitions are involved in measuring NPS and DQE; 2) a cascaded systems analysis shows that the drift induces a global positive offset to the measured autocovariance function, and the offset is quantitatively related to the NPS error at k = 0; 3) based on the measured autocovariance data, drift-induced offset can be estimated, so that errors in the measured NPS(k)| k=0 and DQE(k)| k=0 can be corrected. Both numerical simulations with known ground truth for DQE0 and experimental studies were performed to validate the proposed measurement method. The results demonstrated that the method mitigates the undesirable influence of system drift in DQE(k)| k=0 and DQE0, allowing the measured values consistent with the classical definition of zero-frequency DQE.
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Affiliation(s)
- Xu Ji
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, United States of America
| | - Mang Feng
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, United States of America
| | - Ran Zhang
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, United States of America
| | - Guang-Hong Chen
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, United States of America
- Department of Radiology, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI 53792, United States of America
| | - Ke Li
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, United States of America
- Department of Radiology, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI 53792, United States of America
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Wallyn J, Anton N, Akram S, Vandamme TF. Biomedical Imaging: Principles, Technologies, Clinical Aspects, Contrast Agents, Limitations and Future Trends in Nanomedicines. Pharm Res 2019; 36:78. [PMID: 30945009 DOI: 10.1007/s11095-019-2608-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 03/11/2019] [Indexed: 12/11/2022]
Abstract
This review article presents the state-of-the-art in the major imaging modalities supplying relevant information on patient health by real-time monitoring to establish an accurate diagnosis and potential treatment plan. We draw a comprehensive comparison between all imagers and ultimately end with our focus on two main types of scanners: X-ray CT and MRI scanners. Numerous types of imaging probes for both imaging techniques are described, as well as reviewing their strengths and limitations, thereby showing the current need for the development of new diagnostic contrast agents (CAs). The role of nanoparticles in the design of CAs is then extensively detailed, reviewed and discussed. We show how nanoparticulate agents should be promising alternatives to molecular ones and how they are already paving new routes in the field of nanomedicine.
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Abstract
X-ray luminescence computed tomography (XLCT) is an emerging hybrid molecular imaging modality and has shown great promises in overcoming the strong optical scattering in deep tissues. Though the narrow x-ray beam based XLCT imaging has been demonstrated to obtain high spatial resolution at depth, it suffers from a relatively long measurement time, hindering its practical applications. Recently, we have designed a focused x-ray beam based XLCT imaging system and have successfully performed imaging in about 7.5 seconds per section for a mouse sized object. However, its high spatial resolution capacity has not been fully implemented yet. In this paper, with a superfine focused x-ray beam we design a focused-x-ray luminescence tomography (FXLT) system for spatial resolution up to 94 μm. First, we have described our design in details. Then, we estimate the performance of the designed FXLT imaging system. Lastly, we have found that the spatial resolution of FXLT can be further improved by reducing the scan step size, which has been demonstrated by numerical simulations.
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Affiliation(s)
- Michael C. Lun
- Department of Bioengineering, University of California, Merced, 5200 North Lake Road, Merced, CA 95343, USA
| | - Changqing Li
- Department of Bioengineering, University of California, Merced, 5200 North Lake Road, Merced, CA 95343, USA
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Darvish-Molla S, Reno MC, Sattarivand M. Patient-specific pixel-based weighting factor dual-energy x-ray imaging system using a priori CT data. Med Phys 2019; 46:528-543. [PMID: 30582871 DOI: 10.1002/mp.13354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 12/16/2022] Open
Abstract
PURPOSE The purpose of this study was to develop a novel patient-specific pixel-based weighting factor dual-energy (PP-DE) algorithm to effectively suppress bone throughout the image and overcome the limitation of the conventional DE algorithm with constant weighting factor which is restricted to regions with uniform patient thickness. Additionally, to derive theoretical expressions to describe the dependence of the weighting factors on several imaging parameters and validate them with measurement. METHODS A step phantom was constructed consisting of slabs of solid water and bone materials. Thicknesses of bone ranged [0-6] cm in one direction and solid water [5-30] cm in the other direction. Projection images at 60 and 140 kVp were acquired using a clinical imaging system. Optimal weighting factors were found by iteratively varying it in the range [0-1.4], where bone and soft-tissue contrast-to-noise ratio (CNR) reached zero. Bone and soft-tissue digitally reconstructed thicknesses were created using computed tomography (CT) images of a Rando phantom and ray tracing techniques. A weighting factor image (ω) was calculated using digitally reconstructed thicknesses (DRTs) and precalculated weighting factors from the step phantom. This ω image was then used to generate a PP-DE image. The PP-DE image was compared to the conventional DE image which uses a constant weighting factor throughout the image. The effect of the misaligned ω image on PP-DE images was investigated by acquiring LE and HE images at various shifts of Rando phantom. A rigid registration was used based on mutual information algorithm in Matlab. The signal-to-noise ratios (SNR) were calculated in the step phantom for the PP-DE image and compared to that of conventional DE technique. Analytical expressions for theoretical weighting factors were derived which included various effects such as beam hardening, scatter, and detector response. The analytical expressions were simulated in Spektr3.0 for different bone and solid water thicknesses as per the step phantom. A tray of steel pins was constructed and used with the step phantom to remove the scattered radiation. The simulated theoretical weighting factors were validated by comparing to those from the step phantom measurement. RESULTS Optimal weighting factor values for the step phantom varied from 0.633 to 1.372 depending on region thickness. Thicker regions required larger weighting factors for bone cancellation. The PP-DE image of the Rando phantom favorably cancelled both ribs and spine, whereas in the conventional DE image, only one could be cancelled at a time. The misaligned ω image was less effective in removing all bones indicating the importance of alignment as part of the PP-DE algorithm implementation. The SNRs for the PP-DE image was larger than those of the conventional DE images for regions which required smaller weighting factors for bone suppression. Comparisons of measured and simulated weighting factors demonstrated a 3% agreement for all bone overlapped regions except for the thickest region with 30 cm of solid water overlapped with 6 cm bone where the signal was lost due to excess attenuation. CONCLUSIONS A novel PP-DE algorithm was developed which can create higher quality DE images with enhanced bone cancellation and improved noise characteristics compared to conventional DE technique. In addition, theoretical weighting factor expressions were derived and validated against measurement.
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Affiliation(s)
- Sahar Darvish-Molla
- Department of Radiation Oncology (Medical Physics), Nova Scotia Cancer Centre, Halifax, NS, B3H 4R2, Canada
| | - Michael C Reno
- Department of Radiation Oncology (Medical Physics), Nova Scotia Cancer Centre, Halifax, NS, B3H 4R2, Canada.,Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, B3H 4J5, Canada
| | - Mike Sattarivand
- Department of Radiation Oncology (Medical Physics), Nova Scotia Cancer Centre, Halifax, NS, B3H 4R2, Canada.,Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, B3H 4J5, Canada.,Department of Radiation Oncology, Dalhousie University, Halifax, NS, B3H 2Y9, Canada
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Persson M, Rajbhandary PL, Pelc NJ. A framework for performance characterization of energy-resolving photon-counting detectors. Med Phys 2018; 45:4897-4915. [PMID: 30191571 DOI: 10.1002/mp.13172] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 07/19/2018] [Accepted: 08/29/2018] [Indexed: 01/12/2023] Open
Abstract
PURPOSE Photon-counting, energy-resolving detectors are subject to intense research interest, and there is a need for a general framework for performance assessment of these detectors. The commonly used linear-systems theory framework, which measures detector performance in terms of noise-equivalent quanta (NEQ) and detective quantum efficiency (DQE) is widely used for characterizing conventional x-ray detectors but does not take energy-resolving capabilities into account. The purpose of this work is to extend this framework to encompass energy-resolving photon-counting detectors and elucidate how the imperfect energy response and other imperfections in real-world detectors affect imaging performance, both for feature detection and for material quantification tasks. METHOD We generalize NEQ and DQE to matrix-valued quantities as functions of spatial frequency, and show how these matrices can be calculated from simple Monte Carlo simulations. To demonstrate how the new metrics can be interpreted, we compute them for simplified models of fluorescence and Compton scatter in a photon-counting detector and for a Monte Carlo model of a CdTe detector with 0.5 × 0.5 mm 2 pixels. RESULTS Our results show that the ideal-linear-observer performance for any detection or material quantification task can be calculated from the proposed generalized NEQ and DQE metrics. We also demonstrate that the proposed NEQ metric is closely related to a generalized version of the Cramér-Rao lower bound commonly used for assessing material quantification performance. Off-diagonal elements in the NEQ and DQE matrices are shown to be related to loss of energy information due to imperfect energy resolution. The Monte Carlo model of the CdTe detector predicts a zero-frequency dose efficiency relative to an ideal detector of 0.86 and 0.65 for detecting water and bone, respectively. When the task instead is to quantify these materials, the corresponding values are 0.34 for water and 0.26 for bone. CONCLUSIONS We have developed a framework for assessing the performance of photon-counting energy-resolving detectors and shown that the matrix-valued NEQ and DQE metrics contain sufficient information for calculating the dose efficiency for both detection and quantification tasks, the task having any spatial and energy dependence. This framework will be beneficial for the development and optimization of photon-counting x-ray detectors.
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Affiliation(s)
- Mats Persson
- Departments of Bioengineering and Radiology, Stanford University, Stanford, CA, 94305, USA
| | - Paurakh L Rajbhandary
- Departments of Electrical Engineering and Radiology, Stanford University, Stanford, CA, 94305, USA
| | - Norbert J Pelc
- Departments of Bioengineering, Radiology and Electrical Engineering, Stanford University, Stanford, CA, 94305, USA
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Ji X, Zhang R, Chen GH, Li K. Impact of anti-charge sharing on the zero-frequency detective quantum efficiency of CdTe-based photon counting detector system: cascaded systems analysis and experimental validation. Phys Med Biol 2018; 63:095003. [PMID: 29582785 PMCID: PMC5975362 DOI: 10.1088/1361-6560/aab9c9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Inter-pixel communication and anti-charge sharing (ACS) technologies have been introduced to photon counting detector (PCD) systems to address the undesirable charge sharing problem. In addition to improving the energy resolution of PCD, ACS may also influence other aspects of PCD performance such as detector multiplicity (i.e. the number of pixels triggered by each interacted photon) and detective quantum efficiency (DQE). In this work, a theoretical model was developed to address how ACS impacts the multiplicity and zero-frequency DQE [DQE(0)] of PCD systems. The work focused on cadmium telluride (CdTe)-based PCD that often involves the generation and transport of K-fluorescence photons. Under the parallel cascaded systems analysis framework, the theory takes both photoelectric and scattering effects into account, and it also considers both the reabsorption and escape of photons. In a new theoretical treatment of ACS, it was considered as a modified version of the conventional single pixel (i.e. non-ACS) mode, but with reduced charge spreading distance and K-fluorescence travel distance. The proposed theoretical model does not require prior knowledge of the detailed ACS implementation method for each specific PCD, and its parameters can be experimentally determined using a radioisotope without invoking any Monte-Carlo simulation. After determining the model parameters, independent validation experiments were performed using a diagnostic x-ray tube and four different polychromatic beams (from 50 to 120 kVp). Both the theoretical and experimental results demonstrate that ACS increased the first and second moments of multiplicity for a majority of the x-ray energy and threshold levels tested, except when the threshold level was much lower than the x-ray energy level. However, ACS always improved DQE(0) at all energy and threshold levels tested.
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Affiliation(s)
- Xu Ji
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705
| | - Ran Zhang
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705
| | - Guang-Hong Chen
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705
- Department of Radiology, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI 53792
| | - Ke Li
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705
- Department of Radiology, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI 53792
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Persson M, Holmin S, Karlsson S, Bornefalk H, Danielsson M. Subpixel x-ray imaging with an energy-resolving detector. J Med Imaging (Bellingham) 2018; 5:013507. [PMID: 29564367 DOI: 10.1117/1.jmi.5.1.013507] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 02/26/2018] [Indexed: 11/14/2022] Open
Abstract
The detector pixel size can be a severe limitation in x-ray imaging of fine details in the human body. We demonstrate a method of using spectral x-ray measurements to image the spatial distribution of the linear attenuation coefficient on a length scale smaller than one pixel, based on the fact that interfaces parallel to the x-ray beam have a unique spectral response, which distinguishes them from homogeneous materials. We evaluate the method in a simulation study by simulating projection imaging of the border of an iodine insert with [Formula: see text] in a soft tissue phantom. The results show that the projected iodine profile can be recovered with an RMS resolution of 5% to 34% of the pixel size, using an ideal energy-resolving detector. We also validate this method in an experimental study by imaging an iodine insert in a polyethylene phantom using a photon-counting silicon-strip detector. The results show that abrupt and gradual transitions can be distinguished based on the transmitted x-ray spectrum, in good agreement with simulations. The demonstrated method may potentially be used for improving visualization of blood vessel boundaries, e.g., in acute stroke care.
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Affiliation(s)
- Mats Persson
- Royal Institute of Technology, Department of Physics, Stockholm, Sweden
| | - Staffan Holmin
- Karolinska Institutet, Department of Clinical Neuroscience, Stockholm, Sweden.,Karolinska University Hospital, Department of Neuroradiology, Stockholm, Sweden
| | - Staffan Karlsson
- Royal Institute of Technology, Department of Physics, Stockholm, Sweden
| | - Hans Bornefalk
- Royal Institute of Technology, Department of Physics, Stockholm, Sweden
| | - Mats Danielsson
- Royal Institute of Technology, Department of Physics, Stockholm, Sweden
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Fischer P, Faranesh A, Pohl T, Maier A, Rogers T, Ratnayaka K, Lederman R, Hornegger J. An MR-Based Model for Cardio-Respiratory Motion Compensation of Overlays in X-Ray Fluoroscopy. IEEE Trans Med Imaging 2018; 37:47-60. [PMID: 28692969 PMCID: PMC5750091 DOI: 10.1109/tmi.2017.2723545] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In X-ray fluoroscopy, static overlays are used to visualize soft tissue. We propose a system for cardiac and respiratory motion compensation of these overlays. It consists of a 3-D motion model created from real-time magnetic resonance (MR) imaging. Multiple sagittal slices are acquired and retrospectively stacked to consistent 3-D volumes. Slice stacking considers cardiac information derived from the ECG and respiratory information extracted from the images. Additionally, temporal smoothness of the stacking is enhanced. Motion is estimated from the MR volumes using deformable 3-D/3-D registration. The motion model itself is a linear direct correspondence model using the same surrogate signals as slice stacking. In X-ray fluoroscopy, only the surrogate signals need to be extracted to apply the motion model and animate the overlay in real time. For evaluation, points are manually annotated in oblique MR slices and in contrast-enhanced X-ray images. The 2-D Euclidean distance of these points is reduced from 3.85 to 2.75 mm in MR and from 3.0 to 1.8 mm in X-ray compared with the static baseline. Furthermore, the motion-compensated overlays are shown qualitatively as images and videos.
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Zamir A, Hagen C, Diemoz PC, Endrizzi M, Vittoria F, Chen Y, Anastasio MA, Olivo A. Recent advances in edge illumination x-ray phase-contrast tomography. J Med Imaging (Bellingham) 2017; 4:040901. [PMID: 29057286 PMCID: PMC5641577 DOI: 10.1117/1.jmi.4.4.040901] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 09/21/2017] [Indexed: 11/14/2022] Open
Abstract
Edge illumination (EI) is an x-ray phase-contrast imaging technique, exploiting sensitivity to x-ray refraction to visualize features, which are often not detected by conventional absorption-based radiography. The method does not require a high degree of spatial coherence and is achromatic and, therefore, can be implemented with both synchrotron radiation and commercial x-ray tubes. Using different retrieval algorithms, information about an object's attenuation, refraction, and scattering properties can be obtained. In recent years, a theoretical framework has been developed that enables EI computed tomography (CT) and, hence, three-dimensional imaging. This review provides a summary of these advances, covering the development of different image acquisition schemes, retrieval approaches, and applications. These developments constitute an integral part in the transformation of EI CT into a widely spread imaging tool for use in a range of fields.
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Affiliation(s)
- Anna Zamir
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Charlotte Hagen
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Paul C Diemoz
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Marco Endrizzi
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Fabio Vittoria
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Yujia Chen
- Washington University in St. Louis, Department of Biomedical Engineering, St. Louis, Missouri, United States
| | - Mark A Anastasio
- Washington University in St. Louis, Department of Biomedical Engineering, St. Louis, Missouri, United States
| | - Alessandro Olivo
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
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Hernandez AM, Boone JM. Average glandular dose coefficients for pendant-geometry breast CT using realistic breast phantoms. Med Phys 2017; 44:5096-5105. [PMID: 28715130 DOI: 10.1002/mp.12477] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 06/06/2017] [Accepted: 06/26/2017] [Indexed: 02/01/2023] Open
Abstract
PURPOSE To design volume-specific breast phantoms from breast CT (bCT) data sets and estimate the associated normalized mean glandular dose coefficients for breast CT using Monte Carlo methods. METHODS A large cohort of bCT data sets (N = 215) was used to evaluate breast volume into quintiles (plus the top 5%). The average radius profile was then determined for each of the six volume-specific groups and used to both fabricate physical phantoms and generate mathematical phantoms (V1-V6; "V" denotes classification by volume). The MCNP6 Monte Carlo code was used to model a prototype bCT system fabricated at our institution; and this model was validated against physical measurements in the fabricated phantoms. The mathematical phantoms were used to simulate normalized mean glandular dose coefficients for both monoenergetic source photons "DgNCT (E)" (8-70 keV in 1 keV intervals) and polyenergetic x-ray beams "pDgNCT " (35-70 kV in 1 kV intervals). The Monte Carlo code was used to study the influence of breast size (V1 vs. V5) and glandular fraction (6.4% vs. 45.8%) on glandular dose. The pDgNCT coefficients estimated for the V1, V3, and V5 phantoms were also compared to those generated using simple, cylindrical phantoms with equivalent volume and two geometrical constraints including; (a) cylinder radius determined at the breast phantom chest wall "Rcw "; and (b) cylinder radius determined at the breast phantom center-of-mass "RCOM ". RESULTS Satisfactory agreement was observed for dose estimations using MCNP6 compared with both physical measurements in the V1, V3, and V5 phantoms (R2 = 0.995) and reference bCT dose coefficients using simple phantoms (R2 = 0.999). For a 49 kV spectrum with 1.5 mm Al filtration, differences in glandular fraction [6.5% (5th percentile) vs. 45.8% (95th percentile)] had a 13.2% influence on pDgNCT for the V3 phantom, and differences in breast size (V1 vs. V5) had a 16.6% influence on pDgNCT for a breast composed of 17% (median) fibroglandular tissue. For cylindrical phantoms with a radius of RCOM , the differences were 1.5%, 0.1%, and 2.1% compared with the V1, V3, and V5 phantoms, respectively. CONCLUSION Breast phantoms were designed using a large cohort of bCT data sets across a range of six breast sizes. These phantoms were then fabricated and used for the estimation of glandular dose in breast CT. The mathematical phantoms and associated glandular dose coefficients for a range of breast sizes (V1-V6) and glandular fractions (5th to 95th percentiles) are available for interested users.
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Affiliation(s)
- Andrew M Hernandez
- Department of Radiology, Biomedical Engineering Graduate Group, University of California Davis, Sacramento, CA, 95817, USA
| | - John M Boone
- Departments of Radiology and Biomedical Engineering, University of California Davis, Sacramento, CA, 95817, USA
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Renieblas GP, Nogués AT, González AM, Gómez-Leon N, Del Castillo EG. Structural similarity index family for image quality assessment in radiological images. J Med Imaging (Bellingham) 2017; 4:035501. [PMID: 28924574 DOI: 10.1117/1.jmi.4.3.035501] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Accepted: 07/10/2017] [Indexed: 11/14/2022] Open
Abstract
The structural similarity index (SSIM) family is a set of metrics that has demonstrated good agreement with human observers in tasks using reference images. These metrics analyze the viewing distance, edge information between the reference and the test images, changed and preserved edges, textures, and structural similarity of the images. Eight metrics based on that family are proposed. This new set of metrics, together with another eight well-known SSIM family metrics, was tested to predict human performance in some specific tasks closely related to the evaluation of radiological medical images. We used a database of radiological images, comprising different acquisition techniques (MRI and plain films). This database was distorted with different types of distortions (Gaussian blur, noise, etc.) and different levels of degradation. These images were analyzed by a board of radiologists with a double-stimulus methodology, and their results were compared with those obtained from the 16 metrics analyzed and proposed in this research. Our experimental results showed that the readings of human observers were sensitive to the changes and preservation of the edge information between the reference and test images, changes and preservation in the texture, structural component of the images, and simulation of multiple viewing distances. These results showed that several metrics that apply this multifactorial approach (4-G-SSIM, 4-MS-G-SSIM, [Formula: see text], and [Formula: see text]) can be used as good surrogates of a radiologist to analyze the medical quality of an image in an environment with a reference image.
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Affiliation(s)
| | - Agustín Turrero Nogués
- Complutense University, Department of Statistics and Operations Research, Faculty of Medicine, Madrid, Spain
| | | | - Nieves Gómez-Leon
- Autónoma University, Department of Radiology, Princesa Hospital, Madrid, Spain
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42
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Koniczek M, Antonuk LE, El-Mohri Y, Liang AK, Zhao Q. Theoretical investigation of the noise performance of active pixel imaging arrays based on polycrystalline silicon thin film transistors. Med Phys 2017; 44:3491-3503. [PMID: 28376261 DOI: 10.1002/mp.12257] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 02/02/2017] [Accepted: 03/21/2017] [Indexed: 02/01/2023] Open
Abstract
PURPOSE Active matrix flat-panel imagers, which typically incorporate a pixelated array with one a-Si:H thin-film transistor (TFT) per pixel, have become ubiquitous by virtue of many advantages, including large monolithic construction, radiation tolerance, and high DQE. However, at low exposures such as those encountered in fluoroscopy, digital breast tomosynthesis and breast computed tomography, DQE is degraded due to the modest average signal generated per interacting x-ray relative to electronic additive noise levels of ~1000 e, or greater. A promising strategy for overcoming this limitation is to introduce an amplifier into each pixel, referred to as the active pixel (AP) concept. Such circuits provide in-pixel amplification prior to readout as well as facilitate correlated multiple sampling, enhancing signal-to-noise and restoring DQE at low exposures. In this study, a methodology for theoretically investigating the signal and noise performance of imaging array designs is introduced and applied to the case of AP circuits based on low-temperature polycrystalline silicon (poly-Si), a semiconductor suited to manufacture of large area, radiation tolerant arrays. METHODS Computer simulations employing an analog circuit simulator and performed in the temporal domain were used to investigate signal characteristics and major sources of electronic additive noise for various pixel amplifier designs. The noise sources include photodiode shot noise and resistor thermal noise, as well as TFT thermal and flicker noise. TFT signal behavior and flicker noise were parameterized from fits to measurements performed on individual poly-Si test TFTs. The performance of three single-stage and three two-stage pixel amplifier designs were investigated under conditions relevant to fluoroscopy. The study assumes a 20 × 20 cm2 , 150 μm pitch array operated at 30 fps and coupled to a CsI:Tl x-ray converter. Noise simulations were performed as a function of operating conditions, including sampling mode, of the designs. The total electronic additive noise included noise contributions from each circuit component. RESULTS The total noise results were found to exhibit a strong dependence on circuit design and operating conditions, with TFT flicker noise generally found to be the dominant noise contributor. For the single-stage designs, significantly increasing the size of the source-follower TFT substantially reduced flicker noise - with the lowest total noise found to be ~574 e [rms]. For the two-stage designs, in addition to tuning TFT sizes and introducing a low-pass filter, replacing a p-type TFT with a resistor (under the assumption in the study that resistors make no flicker noise contribution) resulted in significant noise reduction - with the lowest total noise found to be ~336 e [rms]. CONCLUSIONS A methodology based on circuit simulations which facilitates comprehensive explorations of signal and noise characteristics has been developed and applied to the case of poly-Si AP arrays. The encouraging results suggest that the electronic additive noise of such devices can be substantially reduced through judicious circuit design, signal amplification, and multiple sampling. This methodology could be extended to explore the noise performance of arrays employing other pixel circuitry such as that for photon counting as well as other semiconductor materials such as a-Si:H and a-IGZO.
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Affiliation(s)
- Martin Koniczek
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Larry E Antonuk
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Youcef El-Mohri
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Albert K Liang
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Qihua Zhao
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 48109, USA
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Ji X, Ge Y, Zhang R, Li K, Chen GH. Studies of signal estimation bias in grating-based x-ray multicontrast imaging. Med Phys 2017; 44:2453-2465. [PMID: 28339107 DOI: 10.1002/mp.12235] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 03/08/2017] [Accepted: 03/12/2017] [Indexed: 11/08/2022] Open
Abstract
PURPOSE In grating-based x-ray multi-contrast imaging, signals of three contrast mechanisms-absorption contrast, differential phase contrast (DPC), and dark-field contrast-can be estimated from the same set of acquired data. The estimated signals, N0 (related to absorption), N1 (related to dark-field), and φ (related to DPC) may be intrinsically biased. However, it is yet unclear how large these biases are and how the data acquisition parameters affect the biases in the extracted signals. The purpose of this paper was to address these questions. METHODS The biases of the extracted signals (i.e., N0 , N1 and φ) were theoretically studied for a well-known signal estimation method. Experimental data acquired from a grating-based x-ray multi-contrast benchtop imaging system with a photon counting detector were used to validate the theoretical results for the signal biases of the three contrast mechanisms. RESULTS Both theoretical and experimental studies showed the following results: (1) The bias of signal estimation for the absorption contrast signal is zero; (2) The bias of signal estimation for N1 is inversely proportional to the number of phase steps and to the average fringe visibility of the grating interferometer, but the ratio between the bias and the signal level (i.e., the relative bias) is independent of the number of phase steps; (3) The bias of signal estimation for φ depends on the mean DPC signal level, the total exposure level of the multi-contrast data acquisition, and the mean fringe visibility of the interferometer. CONCLUSIONS In grating-based x-ray multi-contrast imaging, the estimated absorption contrast signal is unbiased; the estimated dark-field contrast signal is biased, but the relative bias is only dependent on the mean fringe visibility of the interferometer and the exposure level. The estimated DPC signal may be biased, and the bias level depends on the mean signal level, the exposure level, and the interferometer performance.
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Affiliation(s)
- Xu Ji
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Yongshuai Ge
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Ran Zhang
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Ke Li
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.,Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Guang-Hong Chen
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.,Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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44
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Stevens MTR, Parsons DD, Robar JL. Patient specific methods for room-mounted x-ray imagers for monoscopic/stereoscopic prostate motion monitoring. J Appl Clin Med Phys 2017; 18:40-50. [PMID: 28470816 PMCID: PMC5874929 DOI: 10.1002/acm2.12092] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/19/2017] [Accepted: 03/15/2017] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To investigate the improvement of combined monoscopic/stereoscopic prostate motion monitoring with room-mounted dual x-ray systems by adopting patient specific methods. METHODS The linac couch was used as a motion stage to simulate 40 highly dynamic real patient prostate trajectories. For each trajectory, 40 s pretreatment and 120 s treatment periods were extracted to represent a typical treatment fraction. Motion was monitored via continuous stereoscopic x-ray imaging of a single gold fiducial and images were retrospectively divided into periods of stereoscopic and monoscopic imaging to simulate periodic blocking of the room-mounted system by the gantry during arc-based therapy. The accuracy of the combined motion monitoring was assessed by comparison with the linac couch log files. To estimate 3-D marker position during monoscopic imaging, the use of population statistics was compared to both maximum likelihood estimation and stereoscopic localization based estimation of individualized prostate probability density functions (PDFs) from the pretreatment period. The inclusion of intrafraction updating was compared to pretreatment initialization alone. RESULTS Combined mono/stereoscopic localization was successfully implemented. During the transitions from stereoscopic to monoscopic imaging, fiducial localization exhibits sharp discontinuities when population PDFs were employed. Patient specific PDFs successfully reduced the localization error when estimated from stereoscopic localizations, whereas maximum likelihood estimation (MLE) was too unstable in the room-mounted geometry. Intrafraction stereoscopic updating provided further increases in accuracy. Residual error tended to decrease throughout the treatment fraction, as the patient-specific PDFs became more refined. CONCLUSIONS This is the first demonstration of toggled monoscopic/stereoscopic localization using room-mounted dual x-ray imagers, enabling continuous intrafraction motion monitoring for these systems. We showed that both pretreatment individualization and intrafraction updating should be used to provide the most accurate motion monitoring.
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Affiliation(s)
- M Tynan R Stevens
- Department of Radiation Oncology, Dalhousie University, Halifax, NS, Canada
| | - Dave D Parsons
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, Canada
| | - James L Robar
- Department of Radiation Oncology, Dalhousie University, Halifax, NS, Canada.,Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, Canada
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45
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Hagen CK, Diemoz PC, Olivo A. On the relative performance of edge illumination x-ray phase-contrast CT and conventional, attenuation-based CT. Med Phys 2017; 44:1876-1885. [PMID: 28236318 DOI: 10.1002/mp.12179] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 02/15/2017] [Accepted: 02/17/2017] [Indexed: 01/31/2023] Open
Abstract
PURPOSE This article is aimed at comparing edge illumination (EI) x-ray phase contrast computed tomography (PCT) and conventional (attenuation-based) computed tomography (CT), based on their respective contrast and noise transfer. METHODS The noise in raw projections obtained with EI PCT is propagated through every step of the data processing, including phase retrieval and tomographic reconstruction, leading to a description of the noise in the reconstructed phase tomograms. This is compared to the noise in corresponding attenuation tomograms obtained with CT. Specifically, a formula is derived that allows evaluating the relative performance of both modalities on the basis of their contrast-to-noise ratio (CNR), for a variety of experimental parameters. RESULTS The noise power spectra of phase tomograms are shifted towards lower spatial frequencies, leading to a fundamentally different noise texture. The relative performance of EI PCT and CT, in terms of their CNR, is linked to spatial resolution: the CNR in phase tomograms is generally superior to that in attenuation tomograms for higher spatial resolutions (tens to hundreds of μm), but inferior for lower spatial resolutions (hundreds of μm to mm). CONCLUSION These results imply that EI PCT could outperform CT in applications for which high spatial resolutions are key, e.g., small animal or specimen imaging.
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Affiliation(s)
- Charlotte Klara Hagen
- Department of Medical Physics and Bioengineering, University College London, London, WC1E 6BT, UK
| | - Paul Claude Diemoz
- Department of Medical Physics and Bioengineering, University College London, London, WC1E 6BT, UK
| | - Alessandro Olivo
- Department of Medical Physics and Bioengineering, University College London, London, WC1E 6BT, UK
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46
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Gislason-Lee AJ, Keeble C, Egleston D, Bexon J, Kengyelics SM, Davies AG. Comprehensive assessment of patient image quality and radiation dose in latest generation cardiac x-ray equipment for percutaneous coronary interventions. J Med Imaging (Bellingham) 2017; 4:025501. [PMID: 28491907 PMCID: PMC5412945 DOI: 10.1117/1.jmi.4.2.025501] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 04/14/2017] [Indexed: 11/14/2022] Open
Abstract
This study aimed to determine whether a reduction in radiation dose was found for percutaneous coronary interventional (PCI) patients using a cardiac interventional x-ray system with state-of-the-art image enhancement and x-ray optimization, compared to the current generation x-ray system, and to determine the corresponding impact on clinical image quality. Patient procedure dose area product (DAP) and fluoroscopy duration of 131 PCI patient cases from each x-ray system were compared using a Wilcoxon test on median values. Significant reductions in patient dose ([Formula: see text]) were found for the new system with no significant change in fluoroscopy duration ([Formula: see text]); procedure DAP reduced by 64%, fluoroscopy DAP by 51%, and "cine" acquisition DAP by 76%. The image quality of 15 patient angiograms from each x-ray system (30 total) was scored by 75 clinical professionals on a continuous scale for the ability to determine the presence and severity of stenotic lesions; image quality scores were analyzed using a two-sample [Formula: see text]-test. Image quality was reduced by 9% ([Formula: see text]) for the new x-ray system. This demonstrates a substantial reduction in patient dose, from acquisition more than fluoroscopy imaging, with slightly reduced image quality, for the new x-ray system compared to the current generation system.
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Affiliation(s)
| | - Claire Keeble
- University of Leeds, Division of Epidemiology and Biostatistics, Leeds, United Kingdom
| | - Daniel Egleston
- University of Leeds, Division of Biomedical Imaging, Leeds, United Kingdom
| | - Josephine Bexon
- University of Leeds, Division of Biomedical Imaging, Leeds, United Kingdom
| | | | - Andrew G. Davies
- University of Leeds, Division of Biomedical Imaging, Leeds, United Kingdom
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47
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Kaeppler S, Seifert M, Horn F, Pelzer G, Rieger J, Michel T, Maier A, Anton G, Riess C. Talbot-Lau X-ray phase contrast for tiling-based acquisitions without reference scanning. Med Phys 2017; 44:1886-1898. [PMID: 28276081 DOI: 10.1002/mp.12200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 02/09/2017] [Accepted: 02/28/2017] [Indexed: 01/02/2023] Open
Abstract
PURPOSE Grating-based Talbot-Lau interferometers are a popular choice for phase-contrast X-ray acquisitions. Here, an air reference scan has to be acquired prior to an object scan. This particularly complicates acquisition of large objects: large objects are tiled into multiple scans due to the small field of view of current gratings. However, phase reference drifts occurring between these scans may require to repeatedly move the object in and out of the X-ray beam to update the reference information. METHODS We developed an image processing technique that completely removes the need for phase reference scans in tiled acquisitions. We estimate the reference from object scans using a tailored iterated robust regression, using a novel efficient optimizer. RESULTS Our evaluation indicates that the estimated reference is not only close to the acquired reference but also improves the final image quality. We hypothesize that this is because we mitigate errors that are introduced when actually acquiring the reference phase. CONCLUSION Phase-contrast imaging of larger objects may benefit from computational estimation of phase reference data due to reduced scanning complexity and improved image quality.
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Affiliation(s)
- Sebastian Kaeppler
- Pattern Recognition Lab, Friedrich-Alexander-University Erlangen-Nuremberg, Martensstr. 3, 91058, Erlangen, Germany
| | - Maria Seifert
- Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-University Erlangen-Nuremberg, Erwin-Rommel-Str. 1, 91058, Erlangen, Germany
| | - Florian Horn
- Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-University Erlangen-Nuremberg, Erwin-Rommel-Str. 1, 91058, Erlangen, Germany
| | - Georg Pelzer
- Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-University Erlangen-Nuremberg, Erwin-Rommel-Str. 1, 91058, Erlangen, Germany
| | - Jens Rieger
- Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-University Erlangen-Nuremberg, Erwin-Rommel-Str. 1, 91058, Erlangen, Germany
| | - Thilo Michel
- Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-University Erlangen-Nuremberg, Erwin-Rommel-Str. 1, 91058, Erlangen, Germany
| | - Andreas Maier
- Pattern Recognition Lab, Friedrich-Alexander-University Erlangen-Nuremberg, Martensstr. 3, 91058, Erlangen, Germany
| | - Gisela Anton
- Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-University Erlangen-Nuremberg, Erwin-Rommel-Str. 1, 91058, Erlangen, Germany
| | - Christian Riess
- Pattern Recognition Lab, Friedrich-Alexander-University Erlangen-Nuremberg, Martensstr. 3, 91058, Erlangen, Germany
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Rana R, Nagesh SVS, Bednarek DR, Rudin S. Real time implementation of anti-scatter grid artifact elimination method for high resolution x-ray imaging CMOS detectors using Graphics Processing Units (GPUs). Proc SPIE Int Soc Opt Eng 2017; 10132. [PMID: 28659654 DOI: 10.1117/12.2254120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Scatter is one of the most important factors effecting image quality in radiography. One of the best scatter reduction methods in dynamic imaging is an anti-scatter grid. However, when used with high resolution imaging detectors these grids may leave grid-line artifacts with increasing severity as detector resolution improves. The presence of such artifacts can mask important details in the image and degrade image quality. We have previously demonstrated that, in order to remove these artifacts, one must first subtract the residual scatter that penetrates through the grid followed by dividing out a reference grid image; however, this correction must be done fast so that corrected images can be provided in real-time to clinicians. In this study, a standard stationary Smit-Rontgen x-ray grid (line density - 70 lines/cm, grid ratio - 13:1) was used with a high-resolution CMOS detector, the Dexela 1207 (pixel size - 75 micron) to image anthropomorphic head phantoms. For a 15 × 15 cm field-of-view (FOV), scatter profiles of the anthropomorphic head phantoms were estimated then iteratively modified to minimize the structured noise due to the varying grid-line artifacts across the FOV. Images of the head phantoms taken with the grid, before and after the corrections, were compared, demonstrating almost total elimination of the artifact over the full FOV. This correction is done fast using Graphics Processing Units (GPUs), with 7-8 iterations and total time taken to obtain the corrected image of only 87 ms, hence, demonstrating the virtually real-time implementation of the grid-artifact correction technique.
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Affiliation(s)
- R Rana
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY 14214
| | - S V Setlur Nagesh
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY 14214
| | - D R Bednarek
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY 14214
| | - S Rudin
- Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY 14214
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Ji X, Zhang R, Ge Y, Chen GH, Li K. Signal and noise characteristics of a CdTe-based photon counting detector: Cascaded systems analysis and experimental studies. Proc SPIE Int Soc Opt Eng 2017; 10132. [PMID: 30416244 DOI: 10.1117/12.2255063] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Recent advances in single photon counting detectors (PCDs) are opening up new opportunities in medical imaging. However, the performance of PCDs is not flawless. Problems such as charge sharing may deteriorate the performance of PCD. This work studied the dependence of the signal and noise properties of a cadmium telluride (CdTe)-based PCD on the charge sharing effect and the anti-charge sharing (ACS) capability offered by the PCD. Through both serial and parallel cascaded systems analysis, a theoretical model was developed to trace the origin of charge sharing in CdTe-based PCD, which is primarily related to remote k-fluorescence re-absorption and spatial spreading of charge cloud. The ACS process was modeled as a sub-imaging state prior to the energy thresholding stage, and its impact on the noise power spectrum (NPS) of PCD can be qualitatively determined by the theoretical model. To validate the theoretical model, experimental studies with a CdTe-based PCD system (XC-FLITE X1, XCounter AB) was performed. Two x-ray radiation conditions, including an RQA-5 beam and a 40 kVp beam, were used for the NPS measurements. Both theoretical predictions and experimental results showed that ACS makes the NPS of the CdTe-based PCD flatter, which corresponds to reduced noise correlation length. The flatness of the NPS is further boosted by increasing the energy threshold or reducing the x-ray energy, both of which reduce the likelihood of registering multiple counts from the same incidenting x-ray photon.
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Affiliation(s)
- Xu Ji
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Ran Zhang
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Yongshuai Ge
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Guang-Hong Chen
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI.,Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Ke Li
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI.,Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI
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Handschuh S, Beisser CJ, Ruthensteiner B, Metscher BD. Microscopic dual-energy CT (microDECT): a flexible tool for multichannel ex vivo 3D imaging of biological specimens. J Microsc 2017; 267:3-26. [PMID: 28267884 DOI: 10.1111/jmi.12543] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 01/28/2017] [Accepted: 01/29/2017] [Indexed: 12/19/2022]
Abstract
Dual-energy computed tomography (DECT) uses two different x-ray energy spectra in order to differentiate between tissues, materials or elements in a single sample or patient. DECT is becoming increasingly popular in clinical imaging and preclinical in vivo imaging of small animal models, but there have been only very few reports on ex vivo DECT of biological samples at microscopic resolutions. The present study has three main aims. First, we explore the potential of microscopic DECT (microDECT) for delivering isotropic multichannel 3D images of fixed biological samples with standard commercial laboratory-based microCT setups at spatial resolutions reaching below 10 μm. Second, we aim for retaining the maximum image resolution and quality during the material decomposition. Third, we want to test the suitability for microDECT imaging of different contrast agents currently used for ex vivo staining of biological samples. To address these aims, we used microCT scans of four different samples stained with x-ray dense contrast agents. MicroDECT scans were acquired with five different commercial microCT scanners from four companies. We present a detailed description of the microDECT workflow, including sample preparation, image acquisition, image processing and postreconstruction material decomposition, which may serve as practical guide for applying microDECT. The MATLAB script (The Mathworks Inc., Natick, MA, USA) used for material decomposition (including a graphical user interface) is provided as a supplement to this paper (https://github.com/microDECT/DECTDec). In general, the presented microDECT workflow yielded satisfactory results for all tested specimens. Original scan resolutions have been mostly retained in the separate material fractions after basis material decomposition. In addition to decomposition of mineralized tissues (inherent sample contrast) and stained soft tissues, we present a case of double labelling of different soft tissues with subsequent material decomposition. We conclude that, in contrast to in vivo DECT examinations, small ex vivo specimens offer some clear advantages regarding technical parameters of the microCT setup and the use of contrast agents. These include a higher flexibility in source peak voltages and x-ray filters, a lower degree of beam hardening due to small sample size, the lack of restriction to nontoxic contrast agents and the lack of a limit in exposure time and radiation dose. We argue that microDECT, because of its flexibility combined with already established contrast agents and the vast number of currently unexploited stains, will in future represent an important technique for various applications in biological research.
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Affiliation(s)
- S Handschuh
- VetCore Facility for Research, University of Veterinary Medicine Vienna, Vienna, Austria.,Department of Theoretical Biology, University of Vienna, Vienna, Austria
| | - C J Beisser
- Department of Integrative Zoology, University of Vienna, Vienna, Austria
| | | | - B D Metscher
- Department of Theoretical Biology, University of Vienna, Vienna, Austria
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