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Radnia A, Alikhani A, Teimourian B, Nejad MY, Farahani MH, Pashaei F, Rahmim A, Zaidi H, Ay MR. Development of novel low-cost readout electronics for large field-of-view gamma camera detectors. Phys Med 2024; 121:103357. [PMID: 38640631 DOI: 10.1016/j.ejmp.2024.103357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 02/19/2024] [Accepted: 04/15/2024] [Indexed: 04/21/2024] Open
Abstract
PURPOSE Large scintillation crystals-based gamma cameras play a crucial role in nuclear medicine imaging. In this study, a large field-of-view (FOV) gamma detector consisting of 48 square PMTs developed using a new readout electronics, reducing 48 (6 × 8) analog signals to 14 (6 + 8) analog sums of each row and column, with reduced complexity and cost while preserving image quality. METHODS All 14 analog signals were converted to digital signals using AD9257 high-speed analog to digital (ADC) converters driven by the SPARTAN-6 family of field-programmable gate arrays (FPGA) in order to calculate the signal integrals. The positioning algorithm was based on the digital correlated signal enhancement (CSE) algorithm implemented in the acquisition software. The performance characteristics of the developed gamma camera were measured using the NEMA NU 1-2018 standards. RESULTS The measured energy resolution of the developed detector was 8.7 % at 140 keV, with an intrinsic spatial resolution of 3.9 mm. The uniformity was within 0.6 %, while the linearity was within 0.1 %. CONCLUSION The performance evaluation demonstrated that the developed detector has suitable specifications for high-end nuclear medicine imaging.
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Affiliation(s)
- Aram Radnia
- Research Center for Molecular and Cellular Imaging (RCMCI), Advanced Medical Technologies and Equipment Institute (AMTEI), Tehran University of Medical Sciences (TUMS), Tehran, Iran
| | - Amirhossein Alikhani
- Research Center for Molecular and Cellular Imaging (RCMCI), Advanced Medical Technologies and Equipment Institute (AMTEI), Tehran University of Medical Sciences (TUMS), Tehran, Iran
| | - Behnoosh Teimourian
- Research Center for Molecular and Cellular Imaging (RCMCI), Advanced Medical Technologies and Equipment Institute (AMTEI), Tehran University of Medical Sciences (TUMS), Tehran, Iran
| | - Mahyar Yousef Nejad
- Research Center for Molecular and Cellular Imaging (RCMCI), Advanced Medical Technologies and Equipment Institute (AMTEI), Tehran University of Medical Sciences (TUMS), Tehran, Iran
| | - Mohammad Hossein Farahani
- Research Center for Molecular and Cellular Imaging (RCMCI), Advanced Medical Technologies and Equipment Institute (AMTEI), Tehran University of Medical Sciences (TUMS), Tehran, Iran
| | - Fakhereh Pashaei
- Institute for Research, Education and Treatment of Cancer, Tehran, Iran
| | - Arman Rahmim
- Departments of Radiology and Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada; Department of Integrative Oncology, BC Cancer Research Institute, Vancouver, BC, Canada
| | - Habib Zaidi
- Division of Nuclear Medicine & Molecular Imaging, Geneva University Hospital, CH-1211 Geneva, Switzerland; Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, Netherlands; Department of Nuclear Medicine, University of Southern Denmark, 500 Odense, Denmark; University Research and Innovation Center, Óbuda University, Budapest, Hungary.
| | - Mohammad Reza Ay
- Research Center for Molecular and Cellular Imaging (RCMCI), Advanced Medical Technologies and Equipment Institute (AMTEI), Tehran University of Medical Sciences (TUMS), Tehran, Iran; Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran.
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Cosmi V, Wang B, Goorden MC, Beekman FJ. NaI gamma camera performance for high energies: Effects of crystal thickness, photomultiplier tube geometry and light guide thickness. Med Phys 2024. [PMID: 38569052 DOI: 10.1002/mp.17043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 12/18/2023] [Accepted: 03/12/2024] [Indexed: 04/05/2024] Open
Abstract
BACKGROUND Gamma camera imaging, including single photon emission computed tomography (SPECT), is crucial for research, diagnostics, and radionuclide therapy. Gamma cameras are predominantly based on arrays of photon multipliers tubes (PMTs) that read out NaI(Tl) scintillation crystals. In this way, standard gamma cameras can localize ɣ-rays with energies typically ranging from 30 to 360 keV. In the last decade, there has been an increasing interest towards gamma imaging outside this conventional clinical energy range, for example, for theragnostic applications and preclinical multi-isotope positron emission tomography (PET) and PET-SPECT. However, standard gamma cameras are typically equipped with 9.5 mm thick NaI(Tl) crystals which can result in limited sensitivity for these higher energies. PURPOSE Here we investigate to what extent thicker scintillators can improve the photopeak sensitivity for higher energy isotopes while attempting to maintain spatial resolution. METHODS Using Monte Carlo simulations, we analyzed multiple PMT-based configurations of gamma detectors with monolithic NaI (Tl) crystals of 20 and 40 mm thickness. Optimized light guide thickness together with 2-inch round, 3-inch round, 60 × 60 mm2 square, and 76 × 76 mm2 square PMTs were tested. For each setup, we assessed photopeak sensitivity, energy resolution, spatial, and depth-of-interaction (DoI) resolution for conventional (140 keV) and high (511 keV) energy ɣ using a maximum-likelihood algorithm. These metrics were compared to those of a "standard" 9.5 mm-thick crystal detector with 3-inch round PMTs. RESULTS Estimated photopeak sensitivities for 511 keV were 27% and 53% for 20 and 40 mm thick scintillators, which is respectively, 2.2 and 4.4 times higher than for 9.5 mm thickness. In most cases, energy resolution benefits from using square PMTs instead of round ones, regardless of their size. Lateral and DoI spatial resolution are best for smaller PMTs (2-inch round and 60 × 60 mm2 square) which outperform the more cost-effective larger PMT setups (3-inch round and 76 × 76 mm2 square), while PMT layout and shape have negligible (< 10%) effect on resolution. Best spatial resolution was obtained with 60 × 60 mm2 PMTs; for 140 keV, lateral resolution was 3.5 mm irrespective of scintillator thickness, improving to 2.8 and 2.9 mm for 511 keV with 20 and 40 mm thick crystals, respectively. Using the 3-inch round PMTs, lateral resolutions of 4.5 and 3.9 mm for 140 keV and of 3.5 and 3.7 mm for 511 keV were obtained with 20 and 40 mm thick crystals respectively, indicating a moderate performance degradation compared to the 3.5 and 2.9 mm resolution obtained by the standard detector for 140 and 511 keV. Additionally, DoI resolution for 511 keV was 7.0 and 5.6 mm with 20 and 40 mm crystals using 60 × 60 mm2 square PMTs, while with 3-inch round PMTs 12.1 and 5.9 mm were obtained. CONCLUSION Depending on PMT size and shape, the use of thicker scintillator crystals can substantially improve detector sensitivity at high gamma energies, while spatial resolution is slightly improved or mildly degraded compared to standard crystals.
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Affiliation(s)
- Valerio Cosmi
- Department of Radiation Science and Technology, Delft University of Technology, Delft, The Netherlands
| | - Beien Wang
- Department of Radiation Science and Technology, Delft University of Technology, Delft, The Netherlands
| | - Marlies C Goorden
- Department of Radiation Science and Technology, Delft University of Technology, Delft, The Netherlands
| | - Freek J Beekman
- Department of Radiation Science and Technology, Delft University of Technology, Delft, The Netherlands
- Free Bee International, Gouda, The Netherlands
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Meißner T, Cerbone LA, Russo P, Nahm W, Hesser J. Assessment of the axial resolution of a compact gamma camera with coded aperture collimator. EJNMMI Phys 2024; 11:30. [PMID: 38509411 DOI: 10.1186/s40658-024-00631-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 03/06/2024] [Indexed: 03/22/2024] Open
Abstract
PURPOSE Handheld gamma cameras with coded aperture collimators are under investigation for intraoperative imaging in nuclear medicine. Coded apertures are a promising collimation technique for applications such as lymph node localization due to their high sensitivity and the possibility of 3D imaging. We evaluated the axial resolution and computational performance of two reconstruction methods. METHODS An experimental gamma camera was set up consisting of the pixelated semiconductor detector Timepix3 and MURA mask of rank 31 with round holes of 0.08 mm in diameter in a 0.11 mm thick Tungsten sheet. A set of measurements was taken where a point-like gamma source was placed centrally at 21 different positions within the range of 12-100 mm. For each source position, the detector image was reconstructed in 0.5 mm steps around the true source position, resulting in an image stack. The axial resolution was assessed by the full width at half maximum (FWHM) of the contrast-to-noise ratio (CNR) profile along the z-axis of the stack. Two reconstruction methods were compared: MURA Decoding and a 3D maximum likelihood expectation maximization algorithm (3D-MLEM). RESULTS While taking 4400 times longer in computation, 3D-MLEM yielded a smaller axial FWHM and a higher CNR. The axial resolution degraded from 5.3 mm and 1.8 mm at 12 mm to 42.2 mm and 13.5 mm at 100 mm for MURA Decoding and 3D-MLEM respectively. CONCLUSION Our results show that the coded aperture enables the depth estimation of single point-like sources in the near field. Here, 3D-MLEM offered a better axial resolution but was computationally much slower than MURA Decoding, whose reconstruction time is compatible with real-time imaging.
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Affiliation(s)
- Tobias Meißner
- Institute of Biomedical Engineering (IBT), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
- Mannheim Institute for Intelligent Systems in Medicine (MIISM), Heidelberg University, Mannheim, Germany.
| | - Laura Antonia Cerbone
- Scuola Superiore Meridionale, Naples, Italy
- INFN Sezione di Napoli, Istituto Nazionale di Fisica Nucleare, Naples, Italy
| | - Paolo Russo
- INFN Sezione di Napoli, Istituto Nazionale di Fisica Nucleare, Naples, Italy
- Dipartimento di Fisica "Ettore Pancini", Universitá di Napoli Federico II, Naples, Italy
| | - Werner Nahm
- Institute of Biomedical Engineering (IBT), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Jürgen Hesser
- Mannheim Institute for Intelligent Systems in Medicine (MIISM), Heidelberg University, Mannheim, Germany
- Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany
- Central Institute for Computer Engineering (ZITI), Heidelberg University, Heidelberg, Germany
- CZS Heidelberg Center for Model-Based AI, Heidelberg University, Heidelberg, Germany
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Cerić Andelius I, Minarik D, Persson E, Mosén H, Valind K, Trägårdh E, Oddstig J. First clinical experience of a ring-configured cadmium zinc telluride camera: A comparative study versus conventional gamma camera systems. Clin Physiol Funct Imaging 2024; 44:79-88. [PMID: 37592454 DOI: 10.1111/cpf.12853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 05/08/2023] [Accepted: 08/17/2023] [Indexed: 08/19/2023]
Abstract
BACKGROUND A novel semiconductor cadmium zinc telluride (CZT) gamma camera system using a block sequential regularized expectation maximization (BSREM) reconstruction algorithm is now clinically available. Here we investigate how a multi-purpose ring-configurated CZT system can be safely applied in clinics and describe the initial optimization process. METHOD Seventy-six patients (bone-, cardiac- and lung scan) were scanned on a conventional gamma camera (planar and/or single-photon emission computed tomography [SPECT]/SPECT-CT) used in clinical routine and on the ring-configurated CZT camera Starguide (GE Healthcare). These data were used to validate and optimize the Starguide system for routine clinical use. RESULTS Comparable image quality for the Starguide system, to that of the conventional gamma camera, was achieved for bone scan (4 min/bed position [BP] using a relative difference prior [RDP] with gamma 2 and beta 0.4, along with 10 iterations and 10 subsets), cardiac scan (8 min [stress] and 3 min 20 s [rest] using median root prior [MRP] with beta 0.07 non attenuation corrected and 0.008 attenuation corrected and 50 interations and 10 subsets for both stress and rest) and lung scan (10 min [vent] and 5 min [perf] using RDP with gamma 0.5 and beta 0.03 [vent] and 0.02 [perf] and 20 interations and 10 subsets for both vent and perf). CONCLUSIONS It was possible to transition from a conventional gamma camera to the Starguide system as part of the clinical routine, with acceptable image quality. Images from the Starguide system were deemed to be at least as good as those from a conventional gamma camera.
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Affiliation(s)
| | - David Minarik
- Radiation Physics, Skåne University Hospital, Lund/Malmö, Sweden
- Department of Translational Medicine and Wallenberg Centre of Molecular Medicine, Lund University, Malmö, Sweden
| | - Eva Persson
- Department of Clinical Physiology and Nuclear Medicine, Skåne University Hospital, Lund/Malmö, Sweden
- Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Henrik Mosén
- Department of Clinical Physiology and Nuclear Medicine, Skåne University Hospital, Lund/Malmö, Sweden
- Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Kristian Valind
- Department of Translational Medicine and Wallenberg Centre of Molecular Medicine, Lund University, Malmö, Sweden
- Department of Clinical Physiology and Nuclear Medicine, Skåne University Hospital, Lund/Malmö, Sweden
| | - Elin Trägårdh
- Department of Translational Medicine and Wallenberg Centre of Molecular Medicine, Lund University, Malmö, Sweden
- Department of Clinical Physiology and Nuclear Medicine, Skåne University Hospital, Lund/Malmö, Sweden
| | - Jenny Oddstig
- Radiation Physics, Skåne University Hospital, Lund/Malmö, Sweden
- Department of Translational Medicine and Wallenberg Centre of Molecular Medicine, Lund University, Malmö, Sweden
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Brunskog R, Persson M, Jin Z, Danielsson M. First experimental evaluation of a high-resolution deep silicon photon-counting sensor. J Med Imaging (Bellingham) 2024; 11:013503. [PMID: 38314116 PMCID: PMC10832234 DOI: 10.1117/1.jmi.11.1.013503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 01/10/2024] [Accepted: 01/16/2024] [Indexed: 02/06/2024] Open
Abstract
Purpose Current photon-counting computed tomography detectors are limited to a pixel size of around 0.3 to 0.5 mm due to excessive charge sharing degrading the dose efficiency and energy resolution as the pixels become smaller. In this work, we present measurements of a prototype photon-counting detector that leverages the charge sharing to reach a theoretical sub-pixel resolution in the order of 1 μ m . The goal of the study is to validate our Monte-Carlo simulation using measurements, enabling further development. Approach We measure the channel response at the MAX IV Lab, in the DanMAX beamline, with a 35 keV photon beam, and compare the measurements with a 2D Monte Carlo simulation combined with a charge transport model. Only a few channels on the prototype are connected to keep the number of wire bonds low. Results The measurements agree generally well with the simulations with the beam close to the electrodes but diverge as the beam is moved further away. The induced charge cloud signals also seem to increase linearly as the beam is moved away from the electrodes. Conclusions The agreement between measurements and simulations indicates that the Monte-Carlo simulation can accurately model the channel response of the detector with the photon interactions close to the electrodes, which indicates that the unconnected electrodes introduce unwanted effects that need to be further explored. With the same Monte-Carlo simulation previously indicating a resolution of around 1 μ m with similar geometry, the results are promising that an ultra-high resolution detector is not far in the future.
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Affiliation(s)
- Rickard Brunskog
- The Royal Institute of Technology Stockholm, Physics of Medical Imaging, Stockholm, Sweden
- Karolinska University Hospital, MedTechLabs, BioClinicum, Solna, Sweden
| | - Mats Persson
- The Royal Institute of Technology Stockholm, Physics of Medical Imaging, Stockholm, Sweden
- Karolinska University Hospital, MedTechLabs, BioClinicum, Solna, Sweden
| | - Zihui Jin
- The Royal Institute of Technology Stockholm, Physics of Medical Imaging, Stockholm, Sweden
| | - Mats Danielsson
- The Royal Institute of Technology Stockholm, Physics of Medical Imaging, Stockholm, Sweden
- Karolinska University Hospital, MedTechLabs, BioClinicum, Solna, Sweden
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Sheng J, Huang P, Zhou R, Li Z, Yang X, Wang J. A novel reconstruction method combining multi-detector SPECT with an elliptical orbit and computer tomography for cardiac imaging. Sci Rep 2023; 13:15005. [PMID: 37696930 PMCID: PMC10495346 DOI: 10.1038/s41598-023-42163-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 09/06/2023] [Indexed: 09/13/2023] Open
Abstract
The myocardial single photon emission computed tomography (SPECT) is a good study due to its clinical significance in the diagnosis of myocardial disease and the requirement for improving image quality. However, SPECT imaging faces challenges related to low spatial resolution and significant statistical noise, which concerns patient radiation safety. In this paper, a novel reconstruction system combining multi-detector elliptical SPECT (ME-SPECT) and computer tomography (CT) is proposed to enhance spatial resolution and sensitivity. The hybrid imaging system utilizes a slit-slat collimator and elliptical orbit to improve sensitivity and signal-to-noise ratio (SNR), obtains accurate attenuation mapping matrices, and requires prior information from integrated CT. Collimator parameters are corrected based on CT reconstruction results. The SPECT imaging system employs an iterative reconstruction algorithm that utilizes prior knowledge. An iterative reconstruction algorithm based on prior knowledge is applied to the SPECT imaging system, and a method for prioritizing the reconstruction of regions of interest (ROI) is introduced to deal with severely truncated data from ME-SPECT. Simulation results show that the proposed method can significantly improve the system's spatial resolution, SNR, and image fidelity. The proposed method can effectively suppress distortion and artifacts with the higher spatial resolution ordered subsets expectation maximization (OSEM); slit-slat collimation.
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Affiliation(s)
- Jinhua Sheng
- School of Computer Science and Technology, Hangzhou Dianzi University, Hangzhou, 310018, Zhejiang, China.
- Key Laboratory of Intelligent Image Analysis for Sensory and Cognitive Health, Ministry of Industry and Information Technology of China, Hangzhou, 310018, Zhejiang, China.
| | - Pu Huang
- School of Computer Science and Technology, Hangzhou Dianzi University, Hangzhou, 310018, Zhejiang, China
- Key Laboratory of Intelligent Image Analysis for Sensory and Cognitive Health, Ministry of Industry and Information Technology of China, Hangzhou, 310018, Zhejiang, China
| | - Rougang Zhou
- College of Mechanical Engineering, Hangzhou Dianzi University, Hangzhou, 310018, Zhejiang, China
- Mstar Technologies Inc, Hangzhou, 310018, Zhejiang, China
| | - Zhongjin Li
- School of Computer Science and Technology, Hangzhou Dianzi University, Hangzhou, 310018, Zhejiang, China
- Key Laboratory of Intelligent Image Analysis for Sensory and Cognitive Health, Ministry of Industry and Information Technology of China, Hangzhou, 310018, Zhejiang, China
| | - Xiaofan Yang
- School of Computer Science and Technology, Hangzhou Dianzi University, Hangzhou, 310018, Zhejiang, China
- Key Laboratory of Intelligent Image Analysis for Sensory and Cognitive Health, Ministry of Industry and Information Technology of China, Hangzhou, 310018, Zhejiang, China
| | - Jialei Wang
- School of Computer Science and Technology, Hangzhou Dianzi University, Hangzhou, 310018, Zhejiang, China
- Key Laboratory of Intelligent Image Analysis for Sensory and Cognitive Health, Ministry of Industry and Information Technology of China, Hangzhou, 310018, Zhejiang, China
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Hjellström M, Isaksson M. Medical gamma cameras in radiological emergency preparedness: determination of calibration factors and MDA for the GE Discovery NM/CT 670 Pro. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2023; 43:011516. [PMID: 36749985 DOI: 10.1088/1361-6498/acb9a4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 02/07/2023] [Indexed: 06/18/2023]
Abstract
A survey was performed of the available gamma camera models and whole-body counters (WBCs) in Sweden, revealing that there are about 75 gamma cameras and 15 WBCs currently in operation in Sweden. One of the most common gamma camera models (GE Discovery NM/CT 670 Pro), with the collimators removed, was calibrated for152Eu,137Cs,60Co and40K in three different measurement geometries (supine, close-up sitting and distant sitting) for six different phantom sizes (12-110 kg). Minimum detectable activities (MDAs) were calculated for the gamma camera and a typical WBC, both at the Sahlgrenska University Hospital in Gothenburg, Sweden. An energy window of 30-510 keV was used to calibrate the gamma camera. The calibration factors for this gamma camera for supine and close-up sitting geometry, including all phantom sizes, were 138-208 cps kBq-1for152Eu, 63-83 cps kBq-1for137Cs and 99-126 cps kBq-1for60Co; the MDAs were 50-73 Bq for152Eu, 125-198 Bq for137Cs and 83-105 Bq for60Co. The International Commission on Radiological Protection dose coefficients for members of the public were used to calculate the committed effective doses (CEDs) corresponding to the MDAs, showing that CEDs down to a fewμSv can be estimated with this gamma camera for the inhalation of aerosols of absorption type M. The distant sitting geometry was used to enable the estimation of higher contamination levels, and a hypothetical maximum CED was calculated. This was shown to be 256-2000 mSv, depending on the radionuclide and phantom size. However, further investigations are needed into the dead time losses for higher activity levels for the radionuclides studied. The results show that the use of gamma cameras for radiological triage and, in some cases, to estimate the internal activity of relevant radionuclides in radiological and nuclear events, is feasible.
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Affiliation(s)
- Martin Hjellström
- Department of Medical Radiation Sciences, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Mats Isaksson
- Department of Medical Radiation Sciences, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Noori-Asl M, Sayyah-Koohi P. Investigation of Response of the Pixelated CZT SPECT Imaging System and Comparison with the Conventional SPECT System. J Med Phys 2022; 47:374-380. [PMID: 36908490 PMCID: PMC9997538 DOI: 10.4103/jmp.jmp_41_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 09/18/2022] [Accepted: 09/20/2022] [Indexed: 01/11/2023] Open
Abstract
Purpose The aim of this study is to investigate the factors affecting the response of the pixelated CZT SPECT imaging systems and to compare the performance of these systems with the conventional SPECT imaging systems. Materials and Methods By using the simulation technique, the effect of applied voltage, gap size between the anode pixels, and electron cloud mobility on the response of a pixelated CZT SPECT system are investigated. Then, the response of this system is compared with the conventional SPECT system in both single- and dual-radioisotope imaging. Results The results of this study show that increasing the applied voltage, electron cloud mobility or decreasing the gap size, in the optimal range of these parameters obtained in this study, leads to reducing the lateral charge diffusion and consequently improving the probability of the complete charge collection by the target anode pixel. In dual-radioisotope imaging by the pixelated CZT SPECT system, although higher energy resolution results in better separation of photopeaks, the presence of a low-energy tail leads to an overestimation of counts in the low-energy photopeak. Conclusion The use of the optimal values for the applied voltage, gap size, and electron cloud mobility strongly affect the performance of the pixelated CZT SPECT systems. In addition, the presence of a tail restricts the use of these systems for dual-radioisotope imaging and also, the use of the conventional methods for scatter correction.
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Affiliation(s)
- Mahsa Noori-Asl
- Department of Physics, Faculty of Science, University of Mohaghegh Ardabili, Ardabil, Iran
| | - Pooneh Sayyah-Koohi
- Department of Physics, Faculty of Science, University of Mohaghegh Ardabili, Ardabil, Iran
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Lee Y, Park C. Evaluation of TlBr semiconductor detector in gamma camera imaging: Monte Carlo simulation study. NUCLEAR ENGINEERING AND TECHNOLOGY 2022. [DOI: 10.1016/j.net.2022.07.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Herald M, Sykes J, Werner D, Seville J, Windows-Yule C. DEM2GATE: Combining discrete element method simulation with virtual positron emission particle tracking experiments. POWDER TECHNOL 2022. [DOI: 10.1016/j.powtec.2022.117302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Frangos S, Michael K, Exadaktylou P, Giannoula E, Iakovou I. The Anger's camera. Nucl Med Mol Imaging 2022. [DOI: 10.1016/b978-0-12-822960-6.00159-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Camoni L, Pestean C, Testanera G, Costa PF. Basics for nuclear medicine image reconstruction. Nucl Med Mol Imaging 2022. [DOI: 10.1016/b978-0-12-822960-6.00132-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Sundberg C, Persson M, Wikner JJ, Danielsson M. 1-μm spatial resolution in silicon photon-counting CT detectors. J Med Imaging (Bellingham) 2021; 8:063501. [PMID: 34805448 DOI: 10.1117/1.jmi.8.6.063501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 10/27/2021] [Indexed: 11/14/2022] Open
Abstract
Purpose: Spatial resolution for current scintillator-based computed tomography (CT) detectors is limited by the pixel size of about 1 mm. Direct conversion photon-counting detector prototypes with silicon- or cadmium-based detector materials have lately demonstrated spatial resolution equivalent to about 0.3 mm. We propose a development of the deep silicon photon-counting detector which will enable a resolution of 1 μ m , a substantial improvement compared to the state of the art. Approach: With the deep silicon sensor, it is possible to integrate CMOS electronics and reduce the pixel size at the same time as significant on-sensor data processing capability is introduced. A Gaussian curve can then be fitted to the charge cloud created in each interaction.We evaluate the feasibility of measuring the charge cloud shape of Compton interactions for deep silicon to increase the spatial resolution. By combining a Monte Carlo photon simulation with a charge transport model, we study the charge cloud distributions and induced currents as functions of the interaction position. For a simulated deep silicon detector with a pixel size of 12 μ m , we present a method for estimating the interaction position. Results: Using estimations for electronic noise and a lowest threshold of 0.88 keV, we obtain a spatial resolution equivalent to 1.37 μ m in the direction parallel to the silicon wafer and 78.28 μ m in the direction orthogonal to the wafer. Conclusions: We have presented a simulation study of a deep silicon detector with a pixel size of 12 × 500 μ m 2 and a method to estimate the x-ray interaction position with ultra-high resolution. Higher spatial resolution can in general be important to detect smaller details in the image. The very high spatial resolution in one dimension could be a path to a practical implementation of phase contrast imaging in CT.
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Affiliation(s)
- Christel Sundberg
- KTH Royal Institute of Technology, Department of Physics, Stockholm, Sweden
| | - Mats Persson
- KTH Royal Institute of Technology, Department of Physics, Stockholm, Sweden.,Karolinska University Hospital, MedTechLabs, BioClinicum, Solna, Sweden
| | - J Jacob Wikner
- Linköping University, Department of Electrical Engineering, Linköping, Sweden
| | - Mats Danielsson
- KTH Royal Institute of Technology, Department of Physics, Stockholm, Sweden.,Karolinska University Hospital, MedTechLabs, BioClinicum, Solna, Sweden
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Quantitative SPECT (QSPECT) at high count rates with contemporary SPECT/CT systems. EJNMMI Phys 2021; 8:73. [PMID: 34718900 PMCID: PMC8557232 DOI: 10.1186/s40658-021-00421-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 10/14/2021] [Indexed: 12/02/2022] Open
Abstract
Background Accurate QSPECT is crucial in dosimetry-based, personalized radiopharmaceutical therapy with 177Lu and other radionuclides. We compared the quantitative performance of three NaI(Tl)-crystal SPECT/CT systems equipped with low-energy high-resolution collimators from two vendors (Siemens Symbia T6; GE Discovery 670 and NM/CT 870 DR). Methods Using up to 14 GBq of 99mTc in planar mode, we determined the calibration factor and dead-time constant under the assumption that these systems have a paralyzable behaviour. We monitored their response when one or both detectors were activated. QSPECT capability was validated by SPECT/CT imaging of a customized NEMA phantom containing up to 17 GBq of 99mTc. Acquisitions were reconstructed with a third-party ordered subset expectation maximization algorithm. Results The Siemens system had a higher calibration factor (100.0 cps/MBq) and a lower dead-time constant (0.49 μs) than those from GE (75.4–87.5 cps/MBq; 1.74 μs). Activities of up to 3.3 vs. 2.3–2.7 GBq, respectively, were quantifiable by QSPECT before the observed count rate plateaued or decreased. When used in single-detector mode, the QSPECT capability of the former system increased to 5.1 GBq, whereas that of the latter two systems remained independent of the detectors activation mode. Conclusion Despite similar hardware, SPECT/CT systems’ response can significantly differ at high count rate, which impacts their QSPECT capability in a post-therapeutic setting. Supplementary Information The online version contains supplementary material available at 10.1186/s40658-021-00421-3.
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Abstract
In this review, the roles of detectors in various medical imaging techniques were described. Ultrasound, optical (near-infrared spectroscopy and optical coherence tomography) and thermal imaging, magnetic resonance imaging, computed tomography, single-photon emission tomography, positron emission tomography were the imaging modalities considered. For each methodology, the state of the art of detectors mainly used in the systems was described, emphasizing new technologies applied.
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16
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Park CR, Kang SH, Lee Y. Similarity analysis of pixelated CdTe semiconductor gamma camera image using a quadrant bar phantom for nuclear medicine: Monte Carlo simulation study. NUCLEAR ENGINEERING AND TECHNOLOGY 2021. [DOI: 10.1016/j.net.2020.12.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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17
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Chaudhari AJ, Badawi RD. Application-specific nuclear medical in vivoimaging devices. Phys Med Biol 2021; 66. [PMID: 33770765 DOI: 10.1088/1361-6560/abf275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/26/2021] [Indexed: 11/11/2022]
Abstract
Nuclear medical imaging devices, such as those enabling photon emission imaging (gamma camera, single photon emission computed tomography, or positron emission imaging), that are typically used in today's clinics are optimized for assessing large portions of the human body, and are classified as whole-body imaging systems. These systems have known limitations for organ imaging, therefore application-specific devices have been designed, constructed and evaluated. These devices, given their compact nature and superior technical characteristics, such as their higher detection sensitivity and spatial resolution for organ imaging compared to whole-body imaging systems, have shown promise for niche applications. Several of these devices have further been integrated with complementary anatomical imaging devices. The objectives of this review article are to (1) provide an overview of such application-specific nuclear imaging devices that were developed over the past two decades (in the twenty-first century), with emphasis on brain, cardiac, breast, and prostate imaging; and (2) discuss the rationale, advantages and challenges associated with the translation of these devices for routine clinical imaging. Finally, a perspective on the future prospects for application-specific devices is provided, which is that sustained effort is required both to overcome design limitations which impact their utility (where these exist) and to collect the data required to define their clinical value.
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Affiliation(s)
- Abhijit J Chaudhari
- Department of Radiology, University of California Davis, Sacramento, CA 95817, United States of America.,Center for Molecular and Genomic Imaging, University of California Davis, Davis, CA 95616, United States of America
| | - Ramsey D Badawi
- Department of Radiology, University of California Davis, Sacramento, CA 95817, United States of America.,Department of Biomedical Engineering, University of California Davis, Davis, CA 95616, United States of America
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18
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SPECT and SPECT/CT. Mol Imaging 2021. [DOI: 10.1016/b978-0-12-816386-3.00008-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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19
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D'Elia A, Schiavi S, Soluri A, Massari R, Soluri A, Trezza V. Role of Nuclear Imaging to Understand the Neural Substrates of Brain Disorders in Laboratory Animals: Current Status and Future Prospects. Front Behav Neurosci 2020; 14:596509. [PMID: 33362486 PMCID: PMC7759612 DOI: 10.3389/fnbeh.2020.596509] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/23/2020] [Indexed: 12/18/2022] Open
Abstract
Molecular imaging, which allows the real-time visualization, characterization and measurement of biological processes, is becoming increasingly used in neuroscience research. Scintigraphy techniques such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) provide qualitative and quantitative measurement of brain activity in both physiological and pathological states. Laboratory animals, and rodents in particular, are essential in neuroscience research, providing plenty of models of brain disorders. The development of innovative high-resolution small animal imaging systems together with their radiotracers pave the way to the study of brain functioning and neurotransmitter release during behavioral tasks in rodents. The assessment of local changes in the release of neurotransmitters associated with the performance of a given behavioral task is a turning point for the development of new potential drugs for psychiatric and neurological disorders. This review addresses the role of SPECT and PET small animal imaging systems for a better understanding of brain functioning in health and disease states. Brain imaging in rodent models faces a series of challenges since it acts within the boundaries of current imaging in terms of sensitivity and spatial resolution. Several topics are discussed, including technical considerations regarding the strengths and weaknesses of both technologies. Moreover, the application of some of the radioligands developed for small animal nuclear imaging studies is discussed. Then, we examine the changes in metabolic and neurotransmitter activity in various brain areas during task-induced neural activation with special regard to the imaging of opioid, dopaminergic and cannabinoid receptors. Finally, we discuss the current status providing future perspectives on the most innovative imaging techniques in small laboratory animals. The challenges and solutions discussed here might be useful to better understand brain functioning allowing the translation of preclinical results into clinical applications.
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Affiliation(s)
- Annunziata D'Elia
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy.,Section of Biomedical Sciences and Technologies, Department of Science, University "Roma Tre", Rome, Italy
| | - Sara Schiavi
- Section of Biomedical Sciences and Technologies, Department of Science, University "Roma Tre", Rome, Italy
| | - Andrea Soluri
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy
| | - Roberto Massari
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy
| | - Alessandro Soluri
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy
| | - Viviana Trezza
- Section of Biomedical Sciences and Technologies, Department of Science, University "Roma Tre", Rome, Italy
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Kim K, Lee MH, Lee Y. Investigation of a blind-deconvolution framework after noise reduction using a gamma camera in nuclear medicine imaging. NUCLEAR ENGINEERING AND TECHNOLOGY 2020. [DOI: 10.1016/j.net.2020.04.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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21
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Sundberg C, Persson M, Sjölin M, Wikner JJ, Danielsson M. Silicon photon-counting detector for full-field CT using an ASIC with adjustable shaping time. J Med Imaging (Bellingham) 2020; 7:053503. [PMID: 33033734 PMCID: PMC7536358 DOI: 10.1117/1.jmi.7.5.053503] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 09/21/2020] [Indexed: 11/14/2022] Open
Abstract
Purpose: Photon-counting silicon strip detectors are attracting interest for use in next-generation CT scanners. For CT detectors in a clinical environment, it is desirable to have a low power consumption. However, decreasing the power consumption leads to higher noise. This is particularly detrimental for silicon detectors, which require a low noise floor to obtain a good dose efficiency. The increase in noise can be mitigated using a longer shaping time in the readout electronics. This also results in longer pulses, which requires an increased deadtime, thereby degrading the count-rate performance. However, as the photon flux varies greatly during a typical CT scan, not all projection lines require a high count-rate capability. We propose adjusting the shaping time to counteract the increased noise that results from decreasing the power consumption. Approach: To show the potential of increasing the shaping time to decrease the noise level, synchrotron measurements were performed using a detector prototype with two shaping time settings. From the measurements, a simulation model was developed and used to predict the performance of a future channel design. Results: Based on the synchrotron measurements, we show that increasing the shaping time from 28.1 to 39.4 ns decreases the noise and increases the signal-to-noise ratio with 6.5% at low count rates. With the developed simulation model, we predict that a 50% decrease in power can be attained in a proposed future detector design by increasing the shaping time with a factor of 1.875. Conclusion: Our results show that the shaping time can be an important tool to adapt the pulse length and noise level to the photon flux and thereby optimize the dose efficiency of photon-counting silicon detectors.
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Affiliation(s)
- Christel Sundberg
- KTH Royal Institute of Technology, Physics of Medical Imaging, Stockholm, Sweden
| | - Mats Persson
- KTH Royal Institute of Technology, Physics of Medical Imaging, Stockholm, Sweden
| | - Martin Sjölin
- KTH Royal Institute of Technology, Physics of Medical Imaging, Stockholm, Sweden
| | - J Jacob Wikner
- Linköping University, Department of Electrical Engineering, Linköping, Sweden
| | - Mats Danielsson
- KTH Royal Institute of Technology, Physics of Medical Imaging, Stockholm, Sweden
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Roth D, Larsson E, Sundlöv A, Sjögreen Gleisner K. Characterisation of a hand-held CZT-based gamma camera for 177Lu imaging. EJNMMI Phys 2020; 7:46. [PMID: 32642884 PMCID: PMC7343677 DOI: 10.1186/s40658-020-00313-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 06/17/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Currently, hand-held gamma cameras are being developed for 99mTc imaging, mainly for sentinel lymph node detection. These cameras offer advantages, such as mobility and ease of access, and may be useful also for other applications such as biokinetic studies in animals or for imaging of small, superficial structures in patients. In this work, the suitability of a CZT-based hand-held camera for 177Lu imaging is investigated. The energy response of CZT-based detectors combined with the multiple photon emissions of 177Lu poses new challenges compared to 99mTc imaging, and a thorough camera characterisation is thus warranted. METHODS Three collimators (LEHR, LEHS, and MEGP) and three energy windows (55 keV, 113 keV, and 208 keV) are investigated. Characterised camera properties include the system spatial resolution, energy resolution, sensitivity, image uniformity, septal penetration, and temperature dependence. Characterisations are made starting from NEMA guidelines when applicable, with adjustments made when required. The applicability of the camera is demonstrated by imaging of a superficially located tumour in a patient undergoing [177 Lu]Lu-DOTA-TATE therapy. RESULTS Overall, the results are encouraging. Compared to a conventional gamma camera, the hand-held camera generally has a higher sensitivity for a given collimator. For source-collimator distances below 3 cm, the spatial resolution FWHM is within 6 mm for the LEHR and MEGP collimators. Before uniformity correction, the central field-of-view integral uniformity shows best results for the 113-keV window, with values obtained between 11 and 14%. The corresponding values after uniformity correction are within 3%. Effects of septal penetration are observed but are manageable with a proper combination of collimator and energy window setting. Septal penetration and collimator scatter not only affect the 208-keV window but also contribute with counts in lower windows due to energy-tailing effects. The patient study revealed non-uniform uptake patterns in a region that appeared uniform in a conventional gamma camera image. CONCLUSIONS The results show that the hand-held camera can be used for 177Lu imaging. A 113-keV energy window combined with LEHR or MEGP collimators provides the best image system characteristics.
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Affiliation(s)
- Daniel Roth
- Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, Lund, Sweden.
| | - Erik Larsson
- Department of Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Anna Sundlöv
- Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, Lund, Sweden.,Department of Oncology and Pathology, Clinical Sciences Lund, Lund University, Lund, Sweden.,Department of Oncology, Skåne University Hospital, Lund, Sweden
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23
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Panaino CM, Mackay RI, Sotiropoulos M, Kirkby KJ, Taylor MJ. Full 3D position reconstruction of a radioactive source based on a novel hyperbolic geometrical algorithm. COMPUTER PHYSICS COMMUNICATIONS 2020; 252:107131. [PMID: 32624585 PMCID: PMC7233137 DOI: 10.1016/j.cpc.2019.107131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 12/02/2019] [Accepted: 12/16/2019] [Indexed: 06/11/2023]
Abstract
A new method to locate, with millimetre uncertainty, in 3D, a γ -ray source emitting multiple γ -rays in a cascade, employing conventional LaBr3(Ce) scintillation detectors, has been developed. Using 16 detectors in a symmetrical configuration the detector energy and time signals, resulting from the γ -ray interactions, are fed into a new source position reconstruction algorithm. The Monte-Carlo based Geant4 framework has been used to simulate the detector array and a 60Co source located at two positions within the spectrometer central volume. For a source located at (0,0,0) the algorithm reports X, Y, Z values of -0.3 ± 2.5, -0.4 ± 2.4, and -0.6 ± 2.5 mm, respectively. For a source located at (20,20,20) mm, with respect to the array centre, the algorithm reports X, Y, Z values of 20.2 ± 1.0, 20.2 ± 0.9, and 20.1 ± 1.2 mm. The resulting precision of the reconstruction means that this technique could find application in a number of areas including nuclear medicine, national security, radioactive waste assay and proton beam therapy.
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Affiliation(s)
| | - Ranald I. Mackay
- Division of Cancer Sciences, University of Manchester, M13 9PL, Manchester, UK
- The Christie NHS Foundation Trust, M20 4BX, Manchester, UK
| | - Marios Sotiropoulos
- Division of Cancer Sciences, University of Manchester, M13 9PL, Manchester, UK
| | - Karen J. Kirkby
- Division of Cancer Sciences, University of Manchester, M13 9PL, Manchester, UK
- The Christie NHS Foundation Trust, M20 4BX, Manchester, UK
| | - Michael J. Taylor
- Division of Cancer Sciences, University of Manchester, M13 9PL, Manchester, UK
- The Christie NHS Foundation Trust, M20 4BX, Manchester, UK
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24
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Desy A, Bouvet GF, Frezza A, Després P, Beauregard JM. Impact of dead time on quantitative 177Lu-SPECT (QSPECT) and kidney dosimetry during PRRT. EJNMMI Phys 2020; 7:32. [PMID: 32415492 PMCID: PMC7229114 DOI: 10.1186/s40658-020-00303-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 05/05/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Dead time may affect the accuracy of quantitative SPECT (QPSECT), and thus of dosimetry. The aim of this study was to quantify the effect of dead time on 177Lu-QSPECT and renal dosimetry following peptide receptor radionuclide therapy (PRRT) of neuroendocrine tumours. METHODS QSPECT/CT was performed on days 1 and 3 during 564 personalized 177Lu-octreotate cycles in 166 patients. The dead-time data for each scanning time point was compiled. The impact of not correcting QSPECT for the dead time was assessed for the kidney dosimetry. This was also estimated for empiric PRRT by simulating in our cohort a regime of 7.4 GBq/cycle. RESULTS The probability to observe a larger dead time increased with the injected activity. A dead-time loss greater than 5% affected 14.4% and 5.7% of QSPECT scans performed at days 1 and 3, respectively. This resulted in renal absorbed dose estimates that would have been underestimated by more than 5% in 5.7% of cycles if no dead-time correction was applied, with a maximum underestimation of 22.1%. In the simulated empiric regime, this potential dose underestimation would have been limited to 6.2%. CONCLUSION Dead-time correction improves the accuracy of dosimetry in 177Lu radionuclide therapy and is warranted in personalized PRRT.
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Affiliation(s)
- Alessandro Desy
- Cancer Research Centre and Department of Radiology and Nuclear Medicine, Université Laval, Quebec City, Canada.,Department of Medical Imaging and Oncology Division of Research Centre, CHU de Québec-Université Laval, 11 côte du Palais, Quebec City, G1R 2J6, Canada
| | - Guillaume F Bouvet
- Cancer Research Centre and Department of Radiology and Nuclear Medicine, Université Laval, Quebec City, Canada.,Department of Medical Imaging and Oncology Division of Research Centre, CHU de Québec-Université Laval, 11 côte du Palais, Quebec City, G1R 2J6, Canada
| | - Andrea Frezza
- Cancer Research Centre and Department of Physics, Engineering Physics and Optics, Université Laval, Quebec City, QC, Canada
| | - Philippe Després
- Cancer Research Centre and Department of Physics, Engineering Physics and Optics, Université Laval, Quebec City, QC, Canada.,Department of Radiation Oncology and Oncology Division of Research Centre, CHU de Québec-Université Laval, 11 côte du Palais, Quebec City, QC, G1R 2J6, Canada
| | - Jean-Mathieu Beauregard
- Cancer Research Centre and Department of Radiology and Nuclear Medicine, Université Laval, Quebec City, Canada. .,Department of Medical Imaging and Oncology Division of Research Centre, CHU de Québec-Université Laval, 11 côte du Palais, Quebec City, G1R 2J6, Canada.
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25
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Bergeson SD, Ware MJ, Hawk J. CMOS-coupled NaI scintillation detector for gamma decay measurements. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:033320. [PMID: 32259921 DOI: 10.1063/1.5138208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 03/04/2020] [Indexed: 06/11/2023]
Abstract
We report an all-solid-state gamma-ray scintillation detector comprised of a NaI(Tl) crystal and a scientific-grade CMOS camera. After calibration, this detector exhibits excellent linearity over more than three decades of activity levels ranging from 10 mCi to 400 nCi. Because the detector is not counting pulses, dead-time correction is not required. Compared to systems that use a photomultiplier tube, this detector has similar sensitivity and noise characteristics on short time scales. On longer time scales, we measure drifts of a few percent over several days, which can be accommodated through regular calibration. Using this detector, we observe that when high activity sources are brought into close proximity to the NaI crystal, several minutes are required for the measured signal to achieve a steady state.
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Affiliation(s)
| | | | - Jeremy Hawk
- Utah Valley Regional Medical Center, Provo, Utah 84602, USA
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26
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Abstract
Molecular imaging enables both spatial and temporal understanding of the complex biologic systems underlying carcinogenesis and malignant spread. Single-photon emission tomography (SPECT) is a versatile nuclear imaging-based technique with ideal properties to study these processes in vivo in small animal models, as well as to identify potential drug candidates and characterize their antitumor action and potential adverse effects. Small animal SPECT and SPECT-CT (single-photon emission tomography combined with computer tomography) systems continue to evolve, as do the numerous SPECT radiopharmaceutical agents, allowing unprecedented sensitivity and quantitative molecular imaging capabilities. Several of these advances, their specific applications in oncology as well as new areas of exploration are highlighted in this chapter.
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Affiliation(s)
- Benjamin L Franc
- Department of Radiology, Stanford University School of Medicine, 300 Pasteur Drive, H2232, MC 5281, Stanford, CA, 94305-5105, USA.
| | - Youngho Seo
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, USA
| | - Robert Flavell
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, USA
| | - Carina Mari Aparici
- Department of Radiology, Stanford University School of Medicine, 300 Pasteur Drive, H2232, MC 5281, Stanford, CA, 94305-5105, USA
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27
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Abstract
SPECT and PET are nuclear tomographic imaging modalities that visualize functional information based on the accumulation of radioactive tracer molecules. However, SPECT and PET lack anatomical information, which has motivated their combination with an anatomical imaging modality such as CT or MRI. This chapter begins with an overview over the fundamental physics of SPECT and PET followed by a presentation of the respective detector technologies, including detection requirements, principles and different detector concepts. The reader is subsequently provided with an introduction into hybrid imaging concepts, before a dedicated section presents the challenges that arise when hybridizing SPECT or PET with MRI, namely, mutual distortions of the different electromagnetic fields in MRI on the nuclear imaging system and vice versa. The chapter closes with an overview about current hybrid imaging systems of both clinical and preclinical kind. Finally, future developments in hybrid SPECT and PET technology are discussed.
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Affiliation(s)
- Teresa Nolte
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Nicolas Gross-Weege
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany
| | - Volkmar Schulz
- Physics of Molecular Imaging Systems, Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany.
- Hyperion Hybrid Imaging Systems GmbH, Aachen, Germany.
- Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany.
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Caucci L, Liu Z, Jha AK, Han H, Furenlid LR, Barrett HH. Towards continuous-to-continuous 3D imaging in the real world. Phys Med Biol 2019; 64:185007. [PMID: 31470417 PMCID: PMC7038643 DOI: 10.1088/1361-6560/ab3fb5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Imaging systems are often modeled as continuous-to-discrete mappings that map the object (i.e. a function of continuous variables such as space, time, energy, wavelength, etc) to a finite set of measurements. When it comes to reconstruction, some discretized version of the object is almost always assumed, leading to a discrete-to-discrete representation of the imaging system. In this paper, we discuss a method for single-photon emission computed tomography (SPECT) imaging that avoids discrete representations of the object or the imaging system, thus allowing reconstruction on an arbitrarily fine set of points.
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Affiliation(s)
- L Caucci
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724, United States of America. College of Optical Sciences, University of Arizona, Tucson, AZ 85719, United States of America. Author to whom any correspondence should be addressed
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Sakai M, Kubota Y, Parajuli RK, Kikuchi M, Arakawa K, Nakano T. Compton imaging with 99mTc for human imaging. Sci Rep 2019; 9:12906. [PMID: 31501461 PMCID: PMC6733951 DOI: 10.1038/s41598-019-49130-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 08/20/2019] [Indexed: 11/13/2022] Open
Abstract
We have been developing a medical imaging system using a Compton camera and demonstrated the imaging ability of Compton camera for 99mTc-DMSA accumulated in rat kidneys. In this study, we performed imaging experiments using a human body phantom to confirm its applicability to human imaging. Preliminary simulations were conducted using a digital phantom with varying activity ratios between the kidney and body trunk regions. Gamma rays (141 keV) were generated and detected by a Compton camera based on a silicon and cadmium telluride (Si/CdTe) detector. Compton images were reconstructed with the list mode median root prior expectation maximization method. The appropriate number of iterations of the condition was confirmed through simulations. The reconstructed Compton images revealed two bright points in the kidney regions. Furthermore, the numerical value calculated by integrating pixel values inside the region of interest correlated well with the activity of the kidney regions. Finally, experimental studies were conducted to ascertain whether the results of the simulation studies could be reproduced. The kidneys could be successfully visualised. In conclusion, considering that the conditions in this study agree with those of typical human bodies and imaginable experimental setup, the Si/CdTe Compton camera has a high probability of success in human imaging. In addition, our results indicate the capability of (semi-) quantitative analysis using Compton images.
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Affiliation(s)
- Makoto Sakai
- Gunma University Heavy Ion Medical Center, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, Japan.
| | - Yoshiki Kubota
- Gunma University Heavy Ion Medical Center, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, Japan
| | - Raj Kumar Parajuli
- Gunma University Heavy Ion Medical Center, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, Japan.,Department of Molecular Imaging and Theranostics, National Institutes for Quantum and Radiological Science and Technology, Anagawa 4-9-1, Inage, Chiba, Japan
| | - Mikiko Kikuchi
- Gunma University Heavy Ion Medical Center, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, Japan
| | - Kazuo Arakawa
- Gunma University Heavy Ion Medical Center, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, Japan
| | - Takashi Nakano
- Department of Radiation Oncology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, Japan
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Hutton BF, Yamaya T, Furenlid LR. Dedicated Molecular Imaging Systems for Human Neurological Studies. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2019. [DOI: 10.1109/trpms.2019.2912128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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31
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Rausch I, Ruiz A, Valverde-Pascual I, Cal-González J, Beyer T, Carrio I. Performance Evaluation of the Vereos PET/CT System According to the NEMA NU2-2012 Standard. J Nucl Med 2018; 60:561-567. [PMID: 30361382 DOI: 10.2967/jnumed.118.215541] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 09/17/2018] [Indexed: 11/16/2022] Open
Abstract
The aim of this study was to evaluate the physical performance of the Vereos whole-body PET/CT system according to the National Electrical Manufacturers Association (NEMA) NU2-2012 standard and to compare it with other state-of-the-art PET/CT systems. Methods: Spatial resolution, sensitivity, count-rate performance, count rate accuracy, and image quality were assessed. Specifically, spatial resolution was measured using an 18F point-source. System sensitivity was calculated from acquisitions of an 18F line source inside aluminum tubes of varying thickness. Assessment of count rate performance and count rate accuracy was based on measurements of an 18F line source inside a 20-cm-diameter polyethylene cylinder. PET image quality was assessed using a NEMA IQ phantom. All measurements were performed according to the predefined and implemented NEMA NU2-2012 acquisition protocols at a clinical installation of a Vereos PET/CT system. Evaluation was performed using the software provided by the vendor. Results: The average (radial and tangential) transverse spatial resolution was 4.2, 4.5, and 5.5 mm in full width at half maximum for a 1-, 10-, and 20-cm radial offset, respectively, from the center of the field of view. Axial spatial resolution varied between 4.2 and 4.6 mm in full width at half maximum, depending on the radial source position. The average sensitivity was 5.2 cps/kBq. A peak noise-equivalent count (NEC) rate of 153.4 kcps was measured at an activity concentration of 54.9 kBq/mL. The scatter fraction at peak NEC rate was 33.9%, and the maximum count rate error at and below peak NEC rate was 6.8%. Contrast recovery coefficients varied from 54.3% (10-mm sphere) to 83.9% (22-mm sphere) for the hot spheres, and between 81.4% (28-mm sphere) and 87% (37-mm sphere) for the cold spheres for a given sphere-to-background ratio of 4:1. Conclusion: The overall performance characteristics of the Vereos PET/CT system are comparable to state-of-the-art whole-body PET/CT systems with the exception that the peak NEC rate occurs at a higher activity concentration, thus indicating the ability of the Vereos PET/CT system to cover a wider range of activities.
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Affiliation(s)
- Ivo Rausch
- QIMP Team, Center of Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Agustin Ruiz
- Department of Medical Physics and Radiation Protection, Hospital Santa Creu i Sant Pau, Barcelona, Catalonia/Spain; and
| | - Itziar Valverde-Pascual
- Department of Medical Physics and Radiation Protection, Hospital Santa Creu i Sant Pau, Barcelona, Catalonia/Spain; and
| | - Jacobo Cal-González
- QIMP Team, Center of Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Thomas Beyer
- QIMP Team, Center of Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Ignasi Carrio
- Department of Nuclear Medicine, Hospital Santa Creu i Sant Pau, Barcelona, Catalonia/Spain
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Arms L, Smith DW, Flynn J, Palmer W, Martin A, Woldu A, Hua S. Advantages and Limitations of Current Techniques for Analyzing the Biodistribution of Nanoparticles. Front Pharmacol 2018; 9:802. [PMID: 30154715 PMCID: PMC6102329 DOI: 10.3389/fphar.2018.00802] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/03/2018] [Indexed: 12/22/2022] Open
Abstract
Nanomedicines are typically submicrometer-sized carrier materials (nanoparticles) encapsulating therapeutic and/or imaging compounds that are used for the prevention, diagnosis and treatment of diseases. They are increasingly being used to overcome biological barriers in the body to improve the way we deliver compounds to specific tissues and organs. Nanomedicine technology aims to improve the balance between the efficacy and the toxicity of therapeutic compounds. Nanoparticles, one of the key technologies of nanomedicine, can exhibit a combination of physical, chemical and biological characteristics that determine their in vivo behavior. A key component in the translational assessment of nanomedicines is determining the biodistribution of the nanoparticles following in vivo administration in animals and humans. There are a range of techniques available for evaluating nanoparticle biodistribution, including histology, electron microscopy, liquid scintillation counting (LSC), indirectly measuring drug concentrations, in vivo optical imaging, computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine imaging. Each technique has its own advantages and limitations, as well as capabilities for assessing real-time, whole-organ and cellular accumulation. This review will address the principles and methodology of each technique and their advantages and limitations for evaluating in vivo biodistribution of nanoparticles.
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Affiliation(s)
- Lauren Arms
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Doug W. Smith
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Jamie Flynn
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
- Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
| | - William Palmer
- Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, Australia
| | - Antony Martin
- Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, Australia
| | - Ameha Woldu
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
- Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
| | - Susan Hua
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
- Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
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SPECT Gama Kemera Sistemi için Çekim Parametre Değişikliğinin Görüntü Kalitesine Etkisi. JOURNAL OF CONTEMPORARY MEDICINE 2018. [DOI: 10.16899/gopctd.411095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Henscheid N, Clarkson E, Myers KJ, Barrett HH. Physiological random processes in precision cancer therapy. PLoS One 2018; 13:e0199823. [PMID: 29958271 PMCID: PMC6025881 DOI: 10.1371/journal.pone.0199823] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 06/14/2018] [Indexed: 02/07/2023] Open
Abstract
Many different physiological processes affect the growth of malignant lesions and their response to therapy. Each of these processes is spatially and genetically heterogeneous; dynamically evolving in time; controlled by many other physiological processes, and intrinsically random and unpredictable. The objective of this paper is to show that all of these properties of cancer physiology can be treated in a unified, mathematically rigorous way via the theory of random processes. We treat each physiological process as a random function of position and time within a tumor, defining the joint statistics of such functions via the infinite-dimensional characteristic functional. The theory is illustrated by analyzing several models of drug delivery and response of a tumor to therapy. To apply the methodology to precision cancer therapy, we use maximum-likelihood estimation with Emission Computed Tomography (ECT) data to estimate unknown patient-specific physiological parameters, ultimately demonstrating how to predict the probability of tumor control for an individual patient undergoing a proposed therapeutic regimen.
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Affiliation(s)
- Nick Henscheid
- Center for Gamma-Ray Imaging, University of Arizona, Tucson, AZ, United States of America
- Program in Applied Mathematics, University of Arizona, Tucson, AZ, United States of America
| | - Eric Clarkson
- Center for Gamma-Ray Imaging, University of Arizona, Tucson, AZ, United States of America
- Program in Applied Mathematics, University of Arizona, Tucson, AZ, United States of America
- Department of Medical Imaging, University of Arizona, Tucson, AZ, United States of America
- College of Optical Sciences, University of Arizona, Tucson, AZ, United States of America
| | - Kyle J. Myers
- Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD, United States of America
| | - Harrison H. Barrett
- Center for Gamma-Ray Imaging, University of Arizona, Tucson, AZ, United States of America
- Program in Applied Mathematics, University of Arizona, Tucson, AZ, United States of America
- Department of Medical Imaging, University of Arizona, Tucson, AZ, United States of America
- College of Optical Sciences, University of Arizona, Tucson, AZ, United States of America
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Li X, Ruiz-Gonzalez M, Furenlid LR. An edge-readout, multilayer detector for positron emission tomography. Med Phys 2018; 45:2425-2438. [PMID: 29635734 PMCID: PMC5997541 DOI: 10.1002/mp.12906] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 03/02/2018] [Accepted: 03/05/2018] [Indexed: 11/09/2022] Open
Abstract
PURPOSE We present a novel gamma-ray-detector design based on total internal reflection (TIR) of scintillation photons within a crystal that addresses many limitations of traditional PET detectors. Our approach has appealing features, including submillimeter lateral resolution, DOI positioning from layer thickness, and excellent energy resolution. The design places light sensors on the edges of a stack of scintillator slabs separated by small air gaps and exploits the phenomenon that more than 80% of scintillation light emitted during a gamma-ray event reaches the edges of a thin crystal with polished faces due to TIR. Gamma-ray stopping power is achieved by stacking multiple layers, and DOI is determined by which layer the gamma ray interacts in. METHOD The concept of edge readouts of a thin slab was verified by Monte Carlo simulation of scintillation light transport. An LYSO crystal of dimensions 50.8 mm × 50.8 mm × 3.0 mm was modeled with five rectangular SiPMs placed along each edge face. The mean-detector-response functions (MDRFs) were calculated by simulating signals from 511 keV gamma-ray interactions in a grid of locations. Simulations were carried out to study the influence of choice of scintillator material and dimensions, gamma-ray photon energies, introduction of laser or mechanically induced optical barriers (LIOBs, MIOBs), and refractive indices of optical-coupling media and SiPM windows. We also analyzed timing performance including influence of gamma-ray interaction position and presence of optical barriers. We also modeled and built a prototype detector, a 27.4 mm × 27.4 mm × 3.0 mm CsI(Tl) crystal with 4 SiPMs per edge to experimentally validate the results predicted by the simulations. The prototype detector used CsI(Tl) crystals from Proteus outfitted with 16 Hamamatsu model S13360-6050PE MPPCs read out by an AiT-16-channel readout. The MDRFs were measured by scanning the detector with a collimated beam of 662-keV photons from a 137 Cs source. The spatial resolution was experimentally determined by imaging a tungsten slit that created a beam of 0.44 mm (FWHM) width normal to the detector surface. The energy resolution was evaluated by analyzing list-mode data from flood illumination by the 137 Cs source. RESULT We find that in a block-detector-sized LYSO layer read out by five SiPMs per edge, illuminated by 511-keV photons, the average resolution is 1.49 mm (FWHM). With the introduction of optical barriers, average spatial resolution improves to 0.56 mm (FWHM). The DOI resolution is the layer thickness of 3.0 mm. We also find that optical-coupling media and SiPM-window materials have an impact on spatial resolution. The timing simulation with LYSO crystal yields a coincidence resolving time (CRT) of 200-400 ps, which is slightly position dependent. And the introduction of optical barriers has minimum influence. The prototype CsI(Tl) detector, with a smaller area and fewer SiPMs, was measured to have central-area spatial resolutions of 0.70 and 0.39 mm without and with optical barriers, respectively. These results match well with our simulations. An energy resolution of 6.4% was achieved at 662 keV. CONCLUSION A detector design based on a stack of monolithic scintillator layers that uses edge readouts offers several advantages over current block detectors for PET. For example, there is no tradeoff between spatial resolution and detection sensitivity since no reflector material displaces scintillator crystal, and submillimeter resolution can be achieved. DOI information is readily available, and excellent timing and energy resolutions are possible.
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Affiliation(s)
- Xin Li
- Center for Gamma-Ray Imaging, University of Arizona, Tucson, AZ, USA.,College of Optical Sciences, University of Arizona, Tucson, AZ, USA
| | - Maria Ruiz-Gonzalez
- Center for Gamma-Ray Imaging, University of Arizona, Tucson, AZ, USA.,College of Optical Sciences, University of Arizona, Tucson, AZ, USA
| | - Lars R Furenlid
- Center for Gamma-Ray Imaging, University of Arizona, Tucson, AZ, USA.,College of Optical Sciences, University of Arizona, Tucson, AZ, USA
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Spectroscopy and Optimizing Semiconductor Detector Data Under X and γ Photons Using Image Processing Technique. J Med Imaging Radiat Sci 2018; 49:194-200. [PMID: 32074038 DOI: 10.1016/j.jmir.2018.01.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Revised: 01/11/2018] [Accepted: 01/18/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND Spectroscopy is the study of the absorption and emission of light or other radiation by material. It is used to measure intensity of radiation by a function of wavelength. METHODS The spectra of semiconductor detector cadmium tungstate from water, iron, lead, aluminum, and soft tissue targets were experimentally obtained through incident 1E-3 GeV X-ray and 60Co γ-ray and then optimized. The amounts of transmitting radiation attenuation were calculated in 0.2-2 cm thicknesses of the materials using reduction coefficient in theory. Data obtained from FLUKA's simulations were then compared with theoretical values by dividing per theoretical parameter, and mean values were obtained for the attenuation coefficients. Finally, by using the MATLAB software, these corrected coefficients were applied to the simulated data, and the spectra were replotted to optimize the detected values. RESULTS These obtained parameters increased while the material density increased, except for water and soft tissue materials under γ-ray of 60Co. The multiple Compton scattering inside the low-density material affected the γ-photon deviation to reach the crystal. Also, iron had the lowest values of mass attenuation coefficient for both incident radiations, causing a great corrected coefficient and then a greater count in redrawing. DISCUSSION Although the lead material had the greatest density and X-attenuation coefficient, it revealed large amounts for both corrected coefficients, X and γ rays, of 100.90848 and 1.90900, respectively. In count estimation, results showed that the simulated spectra after optimization are more similar to practical spectra. CONCLUSION The policy on reducing radiation damage from ionizing particles necessitates evaluation of various material behaviors to determine which one will be instrumental for imaging or radiotherapy concerns.
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Hutton BF, Erlandsson K, Thielemans K. Advances in clinical molecular imaging instrumentation. Clin Transl Imaging 2018. [DOI: 10.1007/s40336-018-0264-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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van Roosmalen J, Beekman FJ, Goorden MC. System geometry optimization for molecular breast tomosynthesis with focusing multi-pinhole collimators. Phys Med Biol 2017; 63:015018. [PMID: 28994663 DOI: 10.1088/1361-6560/aa9265] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Imaging of 99mTc-labelled tracers is gaining popularity for detecting breast tumours. Recently, we proposed a novel design for molecular breast tomosynthesis (MBT) based on two sliding focusing multi-pinhole collimators that scan a modestly compressed breast. Simulation studies indicate that MBT has the potential to improve the tumour-to-background contrast-to-noise ratio significantly over state-of-the-art planar molecular breast imaging. The aim of the present paper is to optimize the collimator-detector geometry of MBT. Using analytical models, we first optimized sensitivity at different fixed system resolutions (ranging from 5 to 12 mm) by tuning the pinhole diameters and the distance between breast and detector for a whole series of automatically generated multi-pinhole designs. We evaluated both MBT with a conventional continuous crystal detector with 3.2 mm intrinsic resolution and with a pixelated detector with 1.6 mm pixels. Subsequently, full system simulations of a breast phantom containing several lesions were performed for the optimized geometry at each system resolution for both types of detector. From these simulations, we found that tumour-to-background contrast-to-noise ratio was highest for systems in the 7 mm-10 mm system resolution range over which it hardly varied. No significant differences between the two detector types were found.
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Affiliation(s)
- Jarno van Roosmalen
- Section Biomedical Imaging, Delft University of Technology, Delft, Netherlands
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Peterson M, Gustafsson J, Ljungberg M. Monte Carlo-based quantitative pinhole SPECT reconstruction using a ray-tracing back-projector. EJNMMI Phys 2017; 4:32. [PMID: 29247300 PMCID: PMC5732128 DOI: 10.1186/s40658-017-0198-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 11/27/2017] [Indexed: 11/23/2022] Open
Abstract
Background Monte Carlo simulations provide accurate models of nuclear medicine imaging systems as they can properly account for the full physics of photon transport. The accuracy of the model included in the maximum-likelihood–expectation-maximization (ML-EM) reconstruction limits the overall accuracy of the reconstruction results. In this paper, we present a Monte Carlo-based ML-EM reconstruction method for pinhole single-photon emission computed tomography (SPECT) that has been incorporated into the SIMIND Monte Carlo program. The Monte Carlo-based model, which accounts for all of the physical and geometrical characteristics of the camera system, is used in the forward-projection step of the reconstruction, while a simpler model based on ray-tracing is used for back-projection. The aim of this work was to investigate the quantitative accuracy of this combination of forward- and back-projectors in the clinical pinhole camera GE Discovery NM 530c. Results The total activity was estimated in 99mTc-filled spheres with volumes between 0.5 and 16 mL. The total sphere activity was generally overestimated but remained within 10% of the reference activity defined by the phantom preparation. The recovered activity converged towards the reference activity as the number of iterations increased. Furthermore, the recovery of the activity concentrations within the physical boundaries of the spheres increased with increasing sphere volume. Additionally, the Monte Carlo-based reconstruction enabled recovery of the true activity concentration in the myocardium of a cardiac phantom mounted in a torso phantom regardless of whether the torso was empty or water-filled. A qualitative comparison to data reconstructed using the clinical reconstruction algorithm showed that the two methods performed similarly, although the images reconstructed using the clinical software were more uniform due to the incorporation of noise regularization and post-filtration in that reconstruction technique. Conclusions We developed a Monte Carlo-based reconstruction method for pinhole SPECT and evaluated it using phantom measurements. The combination of a Monte Carlo-based forward-projector and a simplified analytical ray-tracing back-projector produced quantitative images of acceptable image quality. No explicit calibration is necessary in this method since the forward-projector model maintains a relationship between the number of counts and activity.
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Affiliation(s)
- Mikael Peterson
- Department of Medical Radiation Physics, Lund University, SE-221 85, Lund, Sweden.
| | - Johan Gustafsson
- Department of Medical Radiation Physics, Lund University, SE-221 85, Lund, Sweden
| | - Michael Ljungberg
- Department of Medical Radiation Physics, Lund University, SE-221 85, Lund, Sweden
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Comparison of Image Uniformity with Photon Counting and Conventional Scintillation Single-Photon Emission Computed Tomography System: A Monte Carlo Simulation Study. NUCLEAR ENGINEERING AND TECHNOLOGY 2017. [DOI: 10.1016/j.net.2016.12.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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He Y, Kontsevoi OY, Stoumpos CC, Trimarchi GG, Islam SM, Liu Z, Kostina SS, Das S, Kim JI, Lin W, Wessels BW, Kanatzidis MG. Defect Antiperovskite Compounds Hg3Q2I2 (Q = S, Se, and Te) for Room-Temperature Hard Radiation Detection. J Am Chem Soc 2017; 139:7939-7951. [DOI: 10.1021/jacs.7b03174] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yihui He
- Department
of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical Engineering
and Computer Science, and ∥Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Oleg Y. Kontsevoi
- Department
of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical Engineering
and Computer Science, and ∥Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Constantinos C. Stoumpos
- Department
of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical Engineering
and Computer Science, and ∥Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Giancarlo G. Trimarchi
- Department
of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical Engineering
and Computer Science, and ∥Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Saiful M. Islam
- Department
of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical Engineering
and Computer Science, and ∥Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Zhifu Liu
- Department
of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical Engineering
and Computer Science, and ∥Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Svetlana S. Kostina
- Department
of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical Engineering
and Computer Science, and ∥Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Sanjib Das
- Department
of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical Engineering
and Computer Science, and ∥Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Joon-Il Kim
- Department
of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical Engineering
and Computer Science, and ∥Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Wenwen Lin
- Department
of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical Engineering
and Computer Science, and ∥Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Bruce W. Wessels
- Department
of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical Engineering
and Computer Science, and ∥Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
| | - Mercouri G. Kanatzidis
- Department
of Chemistry, ‡Department of Materials Science and Engineering, §Department of Electrical Engineering
and Computer Science, and ∥Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
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Suzuki A, Takeuchi W, Ishitsu T, Takahashi I, Ueno Y, Kobashi K, Kubo N, Shiga T, Tamaki N. Quantitative Measurement of Dual-Radioisotopes of Technetium-99m and Iodine-123 in Blood Samples With a Cadmium-Telluride-Based Counting Device. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2017. [DOI: 10.1109/trpms.2017.2686397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lauber DT, Fülöp A, Kovács T, Szigeti K, Máthé D, Szijártó A. State of the art in vivo imaging techniques for laboratory animals. Lab Anim 2017; 51:465-478. [PMID: 28948893 DOI: 10.1177/0023677217695852] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In recent decades, imaging devices have become indispensable tools in the basic sciences, in preclinical research and in modern drug development. The rapidly evolving high-resolution in vivo imaging technologies provide a unique opportunity for studying biological processes of living organisms in real time on a molecular level. State of the art small-animal imaging modalities provide non-invasive images rich in quantitative anatomical and functional information, which renders longitudinal studies possible allowing precise monitoring of disease progression and response to therapy in models of different diseases. The number of animals in a scientific investigation can be substantially reduced using imaging techniques, which is in full compliance with the ethical endeavours for the 3R (reduction, refinement, replacement) policies formulated by Russell and Burch; furthermore, biological variability can be alleviated, as each animal serves as its own control. The most suitable and commonly used imaging modalities for in vivo small-animal imaging are optical imaging (OI), ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI), and finally the methods of nuclear medicine: positron emission tomography (PET) and single photon emission computed tomography (SPECT).
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Affiliation(s)
- David Tibor Lauber
- 1 Hepato-Pancreatico-Biliary Surgery Research Center Hungary, 1st Department of Surgery, Semmelweis University, Budapest, Hungary
| | - András Fülöp
- 1 Hepato-Pancreatico-Biliary Surgery Research Center Hungary, 1st Department of Surgery, Semmelweis University, Budapest, Hungary
| | - Tibor Kovács
- 1 Hepato-Pancreatico-Biliary Surgery Research Center Hungary, 1st Department of Surgery, Semmelweis University, Budapest, Hungary
- 2 Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Krisztián Szigeti
- 2 Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Domokos Máthé
- 2 Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
- 3 CROmed Translational Research Centers Ltd, Budapest, Hungary
| | - Attila Szijártó
- 1 Hepato-Pancreatico-Biliary Surgery Research Center Hungary, 1st Department of Surgery, Semmelweis University, Budapest, Hungary
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Abbaspour S, Mahmoudian B, Islamian JP. Cadmium Telluride Semiconductor Detector for Improved Spatial and Energy Resolution Radioisotopic Imaging. World J Nucl Med 2017; 16:101-107. [PMID: 28553175 PMCID: PMC5436314 DOI: 10.4103/1450-1147.203079] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The detector in single-photon emission computed tomography has played a key role in the quality of the images. Over the past few decades, developments in semiconductor detector technology provided an appropriate substitution for scintillation detectors in terms of high sensitivity, better energy resolution, and also high spatial resolution. One of the considered detectors is cadmium telluride (CdTe). The purpose of this paper is to review the CdTe semiconductor detector used in preclinical studies, small organ and small animal imaging, also research in nuclear medicine and other medical imaging modalities by a complete inspect on the material characteristics, irradiation principles, applications, and epitaxial growth method.
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Affiliation(s)
- Samira Abbaspour
- Department of Medical Physics, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Babak Mahmoudian
- Department of Radiology, Nuclear Medicine Unit, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Jalil Pirayesh Islamian
- Department of Medical Physics, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
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Karimeddini D, Bergmann S. The state of the future is solid. J Nucl Cardiol 2016; 23:1288-1290. [PMID: 26149343 DOI: 10.1007/s12350-015-0224-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 06/16/2015] [Indexed: 11/26/2022]
Affiliation(s)
- David Karimeddini
- Department of Diagnostic Imaging and Therapeutics, University of Connecticut School of Medicine, Farmington, CT, 06030, USA
- UConn Health, 263 Farmington Ave., Mail Code 1915, Farmington, CT, 06030-1915, USA
| | - Steven Bergmann
- Department of Diagnostic Imaging and Therapeutics, University of Connecticut School of Medicine, Farmington, CT, 06030, USA.
- The Pat and Jim Calhoun Cardiology Center, University of Connecticut School of Medicine, Farmington, CT, 06030, USA.
- Department of Internal Medicine, University of Connecticut School of Medicine, Farmington, CT, 06030, USA.
- UConn Health, 263 Farmington Ave., Mail Code 1915, Farmington, CT, 06030-1915, USA.
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Lee S, Kim HJ, Bae SY, Lee Y. Experimental Study of an Easily Controlled Ultra-High-Resolution Pixel-Matched Parallel-Hole Collimator with a Small Cadmium Zinc Telluride Pixelated Gamma Camera System. J Med Imaging Radiat Sci 2016; 47:276-282. [PMID: 31047292 DOI: 10.1016/j.jmir.2016.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 06/01/2016] [Accepted: 06/02/2016] [Indexed: 11/30/2022]
Abstract
The aim of this study was to develop an easily controlled, ultra-high-resolution, tungsten parallel-hole collimator based on a small pixelated gamma camera system. A small cadmium zinc telluride (CZT) pixelated semiconductor detector (eValuator-2500 detector [eV product, Saxonburg, PA]) was evaluated. This detector is composed of an array of 51.2 × 0.8 × 3-mm3 individual CZT crystal elements. The ultra-high-resolution, pixel-matched, parallel-hole collimators consisted of six layers, with the same between the hole and pixel size. The basic characteristics of the imaging system, such as sensitivity and spatial resolution, was measured using a 57Co point source. The measured averages of sensitivity and spatial resolution varied depending on the septal heights of the ultra-high-resolution parallel-hole collimator and source-to-collimator distances. When the 30-mm septal height was at 1-cm source-to-collimator distance, the spatial resolution was approximately 0.85 mm. Using 5-mm septal height, over 0.3 cps/kBq sensitivity was achieved. One advantage of our system is the use of stacked collimators that can select the best combination of system sensitivity and spatial resolution. Our results demonstrated that the developed CZT-pixelated gamma camera system using an ultra-high-resolution parallel-hole collimator of various collimator geometric designs has potential as an effective instrument.
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Affiliation(s)
- Seungwan Lee
- Department of Radiological Science, Konyang University, Daejeon, Republic of Korea
| | - Hee-Joung Kim
- Department of Radiological Science and Convergence Engineering, Yonsei University, Wonju-si, Gangwon-do, Republic of Korea
| | - Se Young Bae
- Department of Radiological Science, Eulji University, Seongnam-si, Gyeonggi-do, Republic of Korea
| | - Youngjin Lee
- Department of Radiological Science, Eulji University, Seongnam-si, Gyeonggi-do, Republic of Korea.
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48
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Lee WW. Recent Advances in Nuclear Cardiology. Nucl Med Mol Imaging 2016; 50:196-206. [PMID: 27540423 DOI: 10.1007/s13139-016-0433-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 06/24/2016] [Indexed: 11/24/2022] Open
Abstract
Nuclear cardiology is one of the major fields of nuclear medicine practice. Myocardial perfusion studies using single-photon emission computed tomography (SPECT) have played a crucial role in the management of coronary artery diseases. Positron emission tomography (PET) has also been considered an important tool for the assessment of myocardial viability and perfusion. However, the recent development of computed tomography (CT)/magnetic resonance imaging (MRI) technologies and growing concerns about the radiation exposure of patients remain serious challenges for nuclear cardiology. In response to these challenges, remarkable achievements and improvements are currently in progress in the field of myocardial perfusion imaging regarding the applicable software and hardware. Additionally, myocardial perfusion positron emission tomography (PET) is receiving increasing attention owing to its unique capability of absolute myocardial blood flow estimation. An F-18-labeled perfusion agent for PET is under clinical trial with promising interim results. The applications of F-18 fluorodeoxyglucose (FDG) and F-18 sodium fluoride (NaF) to cardiovascular diseases have revealed details on the basic pathophysiology of ischemic heart diseases. PET/MRI seems to be particularly promising for nuclear cardiology in the future. Restrictive diseases, such as cardiac sarcoidosis and amyloidosis, are effectively evaluated using a variety of nuclear imaging tools. Considering these advances, the current challenges of nuclear cardiology will become opportunities if more collaborative efforts are devoted to this exciting field of nuclear medicine.
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Affiliation(s)
- Won Woo Lee
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 82, Gumi-ro 173 Beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do 463-707 Korea ; Institute of Radiation Medicine, Medical Research Center, Seoul National University, Seoul, South Korea
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van Roosmalen J, Goorden MC, Beekman FJ. Molecular breast tomosynthesis with scanning focus multi-pinhole cameras. Phys Med Biol 2016; 61:5508-28. [PMID: 27384301 DOI: 10.1088/0031-9155/61/15/5508] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Planar molecular breast imaging (MBI) is rapidly gaining in popularity in diagnostic oncology. To add 3D capabilities, we introduce a novel molecular breast tomosynthesis (MBT) scanner concept based on multi-pinhole collimation. In our design, the patient lies prone with the pendant breast lightly compressed between transparent plates. Integrated webcams view the breast through these plates and allow the operator to designate the scan volume (e.g. a whole breast or a suspected region). The breast is then scanned by translating focusing multi-pinhole plates and NaI(Tl) gamma detectors together in a sequence that optimizes count yield from the volume-of-interest. With simulations, we compared MBT with existing planar MBI. In a breast phantom containing different lesions, MBT improved tumour-to-background contrast-to-noise ratio (CNR) over planar MBI by 12% and 111% for 4.0 and 6.0 mm lesions respectively in case of whole breast scanning. For the same lesions, much larger CNR improvements of 92% and 241% over planar MBI were found in a scan that focused on a breast region containing several lesions. MBT resolved 3.0 mm rods in a Derenzo resolution phantom in the transverse plane compared to 2.5 mm rods distinguished by planar MBI. While planar MBI cannot provide depth information, MBT offered 4.0 mm depth resolution. Our simulations indicate that besides offering 3D localization of increased tracer uptake, multi-pinhole MBT can significantly increase tumour-to-background CNR compared to planar MBI. These properties could be promising for better estimating the position, extend and shape of lesions and distinguishing between single and multiple lesions.
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Affiliation(s)
- Jarno van Roosmalen
- Section Radiation, Detection & Medical Imaging, Delft University of Technology, Delft, The Netherlands
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Ben-Haim S, Kennedy J, Keidar Z. Novel Cadmium Zinc Telluride Devices for Myocardial Perfusion Imaging—Technological Aspects and Clinical Applications. Semin Nucl Med 2016; 46:273-85. [DOI: 10.1053/j.semnuclmed.2016.01.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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