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Abstract
Proton imaging is a promising technology for proton radiotherapy as it can be used for: (1) direct sampling of the tissue stopping power, (2) input information for multi-modality RSP reconstruction, (3) gold-standard calibration against concurrent techniques, (4) tracking motion and (5) pre-treatment positioning. However, no end-to-end characterization of the image quality (signal-to-noise ratio and spatial resolution, blurring uncertainty) against the dose has been done. This work aims to establish a model relating these characteristics and to describe their relationship with proton energy and object size. The imaging noise originates from two processes: the Coulomb scattering with the nucleus, producing a path deviation, and the energy loss straggling with electrons. The noise is found to increases with thickness crossed and, independently, decreases with decreasing energy. The scattering noise is dominant around high-gradient edge whereas the straggling noise is maximal in homogeneous regions. Image quality metrics are found to behave oppositely against energy: lower energy minimizes both the noise and the spatial resolution, with the optimal energy choice depending on the application and location in the imaged object. In conclusion, the model presented will help define an optimal usage of proton imaging to reach the promised application of this technology and establish a fair comparison with other imaging techniques.
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Affiliation(s)
- Charles-Antoine Collins-Fekete
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, United Kingdom. Chemical,Medical and Environmental Science, National Physical Laboratory, Hampton Road, Teddington, United Kingdom
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2
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Abstract
Owing to the favorable physical and biological properties of swift ions in matter, their application to radiation therapy for highly selective cancer treatment is rapidly spreading worldwide. To date, over 90 ion therapy facilities are operational, predominantly with proton beams, and about the same amount is under construction or planning.Over the last decades, considerable developments have been achieved in accelerator technology, beam delivery and medical physics to enhance conformation of the dose delivery to complex shaped tumor volumes, with excellent sparing of surrounding normal tissue and critical organs. Nevertheless, full clinical exploitation of the ion beam advantages is still challenged, especially by uncertainties in the knowledge of the beam range in the actual patient anatomy during the fractionated course of treatment, thus calling for continued multidisciplinary research in this rapidly emerging field.This contribution will review latest developments aiming to image the patient with the same beam quality as for therapy prior to treatment, and to visualize in-vivo the treatment delivery by exploiting irradiation-induced physical emissions, with different level of maturity from proof-of-concept studies in phantoms and first in-silico studies up to clinical testing and initial clinical evaluation.
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Affiliation(s)
- Katia Parodi
- Department of Experimental Physics – Medical Physics, Ludwig-Maximilians-Universität München, Faculty of Physics, Munich, Germany
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3
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Chen X, Liu R, Zhou S, Sun B, Reynoso FJ, Mutic S, Zhang T, Zhao T. A novel design of proton computed tomography detected by multiple-layer ionization chamber with strip chambers: A feasibility study with Monte Carlo simulation. Med Phys 2019; 47:614-625. [PMID: 31705662 DOI: 10.1002/mp.13909] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Uncertainty in proton range can be reduced by proton computed tomography (CT). A novel design of proton CT using a multiple-layer ionization chamber with two strip ionization chambers on the surface is proposed to simplify the imaging acquisition and reconstruction. METHODS Two strip ionization chambers facing the proton source were coupled into a multiple-layer ionization chamber (MLIC). The strip chambers measured locations and lateral profiles of incident proton beamlets after exiting the imaging object, while the integral of depth dose measured in the MLIC was translated into the residual energy of the beamlet. The simulation was performed at five levels of imaging dose to demonstrate the feasibility and performance expectations of our design. The energy of the proton beamlet was set to 150 ± 0.6 MeV. A collimator with a round slit of 1 cm in diameter was placed in the central beam axis upstream from steering magnets. Proton stopping power ratio (SPR) was reconstructed through inverse radon transform on sinograms generated with proton beamlets scanning through an imaging phantom from a half-circle gantry rotation. The imaging phantom was 10 cm in diameter. The base was made of water-equivalent material holding 13-tissue equivalent inserts constructed according to ICRP 1975 (Task Group on Reference Man. "Report of the Task Group on Reference Man: A Report", Pergamon Press 23, 1975). All inserts were 1 cm in diameter with materials ranging from lung to cortical bone. Percentage discrepancies were reported by comparing to the ground truths. The imaging dose and quality were also evaluated. RESULTS The maximum deviation in reconstructed proton SPR from the ground truths was reported to be 1.02% in one of the 13 inserts when the number of protons per beamlet passing through the slit dropped to 103 . Imaging dose was correlated linearly to incident protons and was determined to be 0.54 cGy if 5 × 102 protons per beamlet were used. Imaging quality was acceptable for planning purpose and held consistently through all levels of imaging dose. Spatial resolution was measured as five line pairs per cm consistently in all simulations varying in imaging dose. CONCLUSIONS Proton CT using a multiple-layer ionization chamber with two strip ionization chambers on the surface simplifies data acquisition while achieving excellent accuracy in proton SPR and acceptable spatial resolution. The imaging dose is lower compared to kV CBCT, making it potentially a great tool for localization and plan adaption in proton therapy.
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Affiliation(s)
- Xinyuan Chen
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA.,Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Ruirui Liu
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Shuang Zhou
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,MecKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Baozhou Sun
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Francisco J Reynoso
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Tiezhi Zhang
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA.,Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Tianyu Zhao
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA.,Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA
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Darne CD, Alsanea F, Robertson DG, Guan F, Pan T, Grosshans D, Beddar S. A proton imaging system using a volumetric liquid scintillator: a preliminary study. Biomed Phys Eng Express 2019; 5:045032. [PMID: 32194988 PMCID: PMC7082085 DOI: 10.1088/2057-1976/ab2e4a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
With the expansion of proton radiotherapy for cancer treatments, it has become important to explore proton-based imaging technologies to increase the accuracy of proton treatment planning, alignment, and verification. The purpose of this study is to demonstrate the feasibility of using a volumetric liquid scintillator to generate proton radiographs at a clinically relevant energy (180 MeV) using an integrating detector approach. The volumetric scintillator detector is capable of capturing a wide distribution of residual proton beam energies from a single beam irradiation. It has the potential to reduce acquisition time and imaging dose compared to other proton radiography methods. The imaging system design is comprised of a volumetric (20 × 20 × 20 cm3) organic liquid scintillator working as a residual-range detector and a charge-coupled device (CCD) placed along the beams'-eye-view for capturing radiographic projections. The scintillation light produced within the scintillator volume in response to a 3-dimensional distribution of residual proton beam energies is captured by the CCD as a 2-dimensional grayscale image. A light intensity-to-water equivalent thickness (WET) curve provided WET values based on measured light intensities. The imaging properties of the system, including its contrast, signal-to-noise ratio, and spatial resolution (0.19 line-pairs/mm) were determined. WET values for selected Gammex phantom inserts including solid water, acrylic, and cortical bone were calculated from the radiographs with a relative accuracy of -0.82%, 0.91%, and -2.43%, respectively. Image blurring introduced by system optics was accounted for, resulting in sharper image features. Finally, the system's ability to reconstruct proton CT images from radiographic projections was demonstrated using a filtered back-projection algorithm. The WET retrieved from the reconstructed CT slice was within 0.3% of the WET obtained from MC. In this work, the viability of a cumulative approach to proton imaging using a volumetric liquid scintillator detector and at a clinically-relevant energy was demonstrated.
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Affiliation(s)
- Chinmay D Darne
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Fahed Alsanea
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- The University of Texas MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, TX 77030, USA
| | | | - Fada Guan
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Tinsu Pan
- The University of Texas MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, TX 77030, USA
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - David Grosshans
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sam Beddar
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- The University of Texas MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, TX 77030, USA
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5
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Zhang R, Sharp GC, Jee KW, Cascio E, Harms J, Flanz JB, Lu HM. Iterative optimization of relative stopping power by single detector based multi-projection proton radiography. ACTA ACUST UNITED AC 2019; 64:065022. [DOI: 10.1088/1361-6560/aaf976] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Gianoli C, Meyer S, Magallanes L, Paganelli C, Baroni G, Parodi K. Analytical simulator of proton radiography and tomography for different detector configurations. Phys Med 2019; 59:92-9. [DOI: 10.1016/j.ejmp.2019.03.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 02/08/2019] [Accepted: 03/04/2019] [Indexed: 12/26/2022] Open
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Huo W, Zwart T, Cooley J, Huang K, Finley C, Jee KW, Sharp GC, Rosenthal S, Xu XG, Lu HM. A single detector energy-resolved proton radiography system: a proof of principle study by Monte Carlo simulations. ACTA ACUST UNITED AC 2019; 64:025016. [DOI: 10.1088/1361-6560/aaf96f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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8
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Parodi K, Polf JC. In vivo range verification in particle therapy. Med Phys 2018; 45:e1036-e1050. [PMID: 30421803 DOI: 10.1002/mp.12960] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/11/2018] [Accepted: 05/01/2018] [Indexed: 12/19/2022] Open
Abstract
Exploitation of the full potential offered by ion beams in clinical practice is still hampered by several sources of treatment uncertainties, particularly related to the limitations of our ability to locate the position of the Bragg peak in the tumor. To this end, several efforts are ongoing to improve the characterization of patient position, anatomy, and tissue stopping power properties prior to treatment as well as to enable in vivo verification of the actual dose delivery, or at least beam range, during or shortly after treatment. This contribution critically reviews methods under development or clinical testing for verification of ion therapy, based on pretreatment range and tissue probing as well as the detection of secondary emissions or physiological changes during and after treatment, trying to disentangle approaches of general applicability from those more specific to certain anatomical locations. Moreover, it discusses future directions, which could benefit from an integration of multiple modalities or address novel exploitation of the measurable signals for biologically adapted therapy.
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Affiliation(s)
- Katia Parodi
- Department of Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching b. Munich, 85748, Germany
| | - Jerimy C Polf
- Deparment of Radiation Oncology, Maryland Proton Treatment Center, University of Maryland School of Medicine, 22 South Greene St., Baltimore, MD, 21201, USA
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Hammi A, Koenig S, Weber DC, Poppe B, Lomax AJ. Patient positioning verification for proton therapy using proton radiography. ACTA ACUST UNITED AC 2018; 63:245009. [DOI: 10.1088/1361-6560/aadf79] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Shrestha D, Qin N, Zhang Y, Kalantari F, Niu S, Jia X, Pompos A, Jiang S, Wang J. Iterative reconstruction with boundary detection for carbon ion computed tomography. Phys Med Biol 2018; 63:055002. [PMID: 29384493 DOI: 10.1088/1361-6560/aaac0f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In heavy ion radiation therapy, improving the accuracy in range prediction of the ions inside the patient's body has become essential. Accurate localization of the Bragg peak provides greater conformity of the tumor while sparing healthy tissues. We investigated the use of carbon ions directly for computed tomography (carbon CT) to create the relative stopping power map of a patient's body. The Geant4 toolkit was used to perform a Monte Carlo simulation of the carbon ion trajectories, to study their lateral and angular deflections and the most likely paths, using a water phantom. Geant4 was used to create carbonCT projections of a contrast and spatial resolution phantom, with a cone beam of 430 MeV/u carbon ions. The contrast phantom consisted of cranial bone, lung material, and PMMA inserts while the spatial resolution phantom contained bone and lung material inserts with line pair (lp) densities ranging from 1.67 lp cm-1 through 5 lp cm-1. First, the positions of each carbon ion on the rear and front trackers were used for an approximate reconstruction of the phantom. The phantom boundary was extracted from this approximate reconstruction, by using the position as well as angle information from the four tracking detectors, resulting in the entry and exit locations of the individual ions on the phantom surface. Subsequent reconstruction was performed by the iterative algebraic reconstruction technique coupled with total variation minimization (ART-TV) assuming straight line trajectories for the ions inside the phantom. The influence of number of projections was studied with reconstruction from five different sets of projections: 15, 30, 45, 60 and 90. Additionally, the effect of number of ions on the image quality was investigated by reducing the number of ions/projection while keeping the total number of projections at 60. An estimation of carbon ion range using the carbonCT image resulted in improved range prediction compared to the range calculated using a calibration curve.
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Affiliation(s)
- Deepak Shrestha
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75235, United States of America
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11
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Gehrke T, Amato C, Berke S, Martišíková M. Theoretical and experimental comparison of proton and helium-beam radiography using silicon pixel detectors. ACTA ACUST UNITED AC 2018; 63:035037. [DOI: 10.1088/1361-6560/aaa60f] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Gehrke T, Gallas R, Jäkel O, Martišíková M. Proof of principle of helium-beam radiography using silicon pixel detectors for energy deposition measurement, identification, and tracking of single ions. Med Phys 2018; 45:817-829. [DOI: 10.1002/mp.12723] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 11/30/2017] [Accepted: 12/04/2017] [Indexed: 01/14/2023] Open
Affiliation(s)
- Tim Gehrke
- Department of Radiation Oncology; Heidelberg University Hospital; Heidelberg Germany
- Department of Medical Physics in Radiation Oncology; German Cancer Research Center (DKFZ); Heidelberg Germany
- Heidelberg Institute for Radiation Oncology (HIRO); National Center for Radiation Research in Oncology (NCRO); Heidelberg Germany
- Department of Physics and Astronomy; Heidelberg University; Heidelberg Germany
| | - Raya Gallas
- Department of Medical Physics in Radiation Oncology; German Cancer Research Center (DKFZ); Heidelberg Germany
- Heidelberg Institute for Radiation Oncology (HIRO); National Center for Radiation Research in Oncology (NCRO); Heidelberg Germany
- Department of Physics and Astronomy; Heidelberg University; Heidelberg Germany
| | - Oliver Jäkel
- Department of Radiation Oncology; Heidelberg University Hospital; Heidelberg Germany
- Department of Medical Physics in Radiation Oncology; German Cancer Research Center (DKFZ); Heidelberg Germany
- Heidelberg Institute for Radiation Oncology (HIRO); National Center for Radiation Research in Oncology (NCRO); Heidelberg Germany
- Heidelberg Ion-Beam Therapy Center (HIT); Heidelberg Germany
| | - Maria Martišíková
- Department of Medical Physics in Radiation Oncology; German Cancer Research Center (DKFZ); Heidelberg Germany
- Heidelberg Institute for Radiation Oncology (HIRO); National Center for Radiation Research in Oncology (NCRO); Heidelberg Germany
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Abstract
The use of hadron beams, especially proton beams, in cancer radiotherapy has expanded rapidly in the past two decades. To fully realize the advantages of hadron therapy over traditional x-ray and gamma-ray therapy requires accurate positioning of the Bragg peak throughout the tumor being treated. A half century ago, suggestions had already been made to use protons themselves to develop images of tumors and surrounding tissue, to be used for treatment planning. The recent global expansion of hadron therapy, coupled with modern advances in computation and particle detection, has led several collaborations around the world to develop prototype detector systems and associated reconstruction codes for proton computed tomography (pCT), as well as more simple proton radiography, with the ultimate intent to use such systems in clinical treatment planning and verification. Recent imaging results of phantoms in hospital proton beams are encouraging, but many technical and programmatic challenges remain to be overcome before pCT scanners will be introduced into clinics. This review introduces hadron therapy and the perceived advantages of pCT and proton radiography for treatment planning, reviews its historical development, and discusses the physics related to proton imaging, the associated experimental and computation issues, the technologies used to attack the problem, contemporary efforts in detector and computational development, and the current status and outlook.
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Affiliation(s)
- Robert P Johnson
- Department of Physics, University of California Santa Cruz, 1156 High St., Santa Cruz, CA 95064, United States of America
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Zhang R, Jee KW, Cascio E, Sharp GC, Flanz JB, Lu HM. Improvement of single detector proton radiography by incorporating intensity of time-resolved dose rate functions. ACTA ACUST UNITED AC 2017; 63:015030. [DOI: 10.1088/1361-6560/aa9913] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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15
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Müller J, Neubert C, von Neubeck C, Baumann M, Krause M, Enghardt W, Bütof R, Dietrich A, Lühr A. Proton radiography for inline treatment planning and positioning verification of small animals. Acta Oncol 2017; 56:1399-1405. [PMID: 28835182 DOI: 10.1080/0284186x.2017.1352102] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
INTRODUCTION As proton therapy becomes increasingly well established, there is a need for high-quality clinically relevant in vivo data to gain better insight into the radiobiological effects of proton irradiation on both healthy and tumor tissue. This requires the development of easily applicable setups that allow for efficient, fractionated, image-guided proton irradiation of small animals, the most widely used pre-clinical model. MATERIAL AND METHODS Here, a method is proposed to perform dual-energy proton radiography for inline positioning verification and treatment planning. Dual-energy proton radiography exploits the differential enhancement of object features in two successively measured two-dimensional (2D) dose distributions at two different proton energies. The two raw images show structures that are dominated by energy absorption (absorption mode) or scattering (scattering mode) of protons in the object, respectively. Data post-processing allowed for the separation of both signal contributions in the respective images. The images were evaluated regarding recognizable object details and feasibility of rigid registration to acquired planar X-ray scans. RESULTS Robust, automated rigid registration of proton radiography and planar X-ray images in scattering mode could be reliably achieved with the animal bedding unit used as registration landmark. Distinguishable external and internal features of the imaged mouse included the outer body contour, the skull with substructures, the lung, abdominal structures and the hind legs. Image analysis based on the combined information of both imaging modes allowed image enhancement and calculation of 2D water-equivalent path length (WEPL) maps of the object along the beam direction. DISCUSSION Fractionated irradiation of exposed target volumes (e.g., subcutaneous tumor model or brain) can be realized with the suggested method being used for daily positioning and range determination. Robust registration of X-ray and proton radiography images allows for the irradiation of tumor entities that require conventional computed tomography (CT)-based planning, such as orthotopic lung or brain tumors, similar to conventional patient treatment.
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Affiliation(s)
- Johannes Müller
- OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden – Rossendorf, Dresden, Germany
- Helmholtz-Zentrum Dresden – Rossendorf, Institute of Radiooncology – OncoRay, Dresden, Germany
| | - Christian Neubert
- OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden – Rossendorf, Dresden, Germany
- Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany
| | - Cläre von Neubeck
- OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden – Rossendorf, Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden, Dresden, Germany
- German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Michael Baumann
- OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden – Rossendorf, Dresden, Germany
- Helmholtz-Zentrum Dresden – Rossendorf, Institute of Radiooncology – OncoRay, Dresden, Germany
- German Cancer Research Center (DKFZ), Heidelberg, Germany
- National Center for Tumor Diseases (NCT), Partner Site Dresden, Dresden, Germany
- Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Mechthild Krause
- OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden – Rossendorf, Dresden, Germany
- Helmholtz-Zentrum Dresden – Rossendorf, Institute of Radiooncology – OncoRay, Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden, Dresden, Germany
- National Center for Tumor Diseases (NCT), Partner Site Dresden, Dresden, Germany
- Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Wolfgang Enghardt
- OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden – Rossendorf, Dresden, Germany
- Helmholtz-Zentrum Dresden – Rossendorf, Institute of Radiooncology – OncoRay, Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden, Dresden, Germany
- National Center for Tumor Diseases (NCT), Partner Site Dresden, Dresden, Germany
- Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Rebecca Bütof
- OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden – Rossendorf, Dresden, Germany
- National Center for Tumor Diseases (NCT), Partner Site Dresden, Dresden, Germany
- Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Antje Dietrich
- OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden – Rossendorf, Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden, Dresden, Germany
- German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Armin Lühr
- OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden – Rossendorf, Dresden, Germany
- Helmholtz-Zentrum Dresden – Rossendorf, Institute of Radiooncology – OncoRay, Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden, Dresden, Germany
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Taylor JT, Poludniowski G, Price T, Waltham C, Allport PP, Casse GL, Esposito M, Evans PM, Green S, Manger S, Manolopoulos S, Nieto-Camero J, Parker DJ, Symons J, Allinson NM. An experimental demonstration of a new type of proton computed tomography using a novel silicon tracking detector. Med Phys 2017; 43:6129. [PMID: 27806609 DOI: 10.1118/1.4965809] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Radiography and tomography using proton beams promise benefit to image guidance and treatment planning for proton therapy. A novel proton tracking detector is described and experimental demonstrations at a therapy facility are reported. A new type of proton CT reconstructing relative "scattering power" rather than "stopping power" is also demonstrated. Notably, this new type of imaging does not require the measurement of the residual energies of the protons. METHODS A large area, silicon microstrip tracker with high spatial and temporal resolution has been developed by the Proton Radiotherapy Verification and Dosimetry Applications consortium and commissioned using beams of protons at iThemba LABS, Medical Radiation Department, South Africa. The tracker comprises twelve planes of silicon developed using technology from high energy physics with each plane having an active area of ∼10 × 10 cm segmented into 2048 microstrips. The tracker is organized into four separate units each containing three detectors at 60° to one another creating an x-u-v coordinate system. Pairs of tracking units are used to reconstruct vertices for protons entering and exiting a phantom containing tissue equivalent inserts. By measuring the position and direction of each proton before and after the phantom, the nonlinear path for each proton through an object can be reconstructed. RESULTS Experimental results are reported for tracking the path of protons with initial energies of 125 and 191 MeV. A spherical phantom of 75 mm diameter was imaged by positioning it between the entrance and exit detectors of the tracker. Positions and directions of individual protons were used to create angular distributions and 2D fluence maps of the beam. These results were acquired for 36 equally spaced projections spanning 180°, allowing, for the first time, an experimental CT image based upon the relative scattering power of protons to be reconstructed. CONCLUSIONS Successful tracking of protons through a thick target (phantom) has demonstrated that the tracker discussed in this paper can provide the precise directional information needed to perform proton radiography and tomography. When synchronized with a range telescope, this could enable the reconstruction of proton CT images of stopping power. Furthermore, by measuring the deflection of many protons through a phantom, it was demonstrated that it is possible to reconstruct a new kind of CT image (scattering power) based upon this tracking information alone.
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Affiliation(s)
- J T Taylor
- Department of Physics, University of Liverpool, Oxford Street, Liverpool L69 7ZE, United Kingdom
| | - G Poludniowski
- Department of Medical Physics, Karolinska University Hospital, SE-171 76 Stockholm, Sweden and Centre for Vision Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - T Price
- School of Physics and Astronomy, University of Birmingham, Birmingham B25 2TT, United Kingdom
| | - C Waltham
- Laboratory of Vision Engineering, School of Computer Science, University of Lincoln, Lincoln LN6 7TS, United Kingdom
| | - P P Allport
- School of Physics and Astronomy, University of Birmingham, Birmingham B25 2TT, United Kingdom
| | - G L Casse
- Department of Physics, University of Liverpool, Oxford Street, Liverpool L69 7ZE, United Kingdom
| | - M Esposito
- Laboratory of Vision Engineering, School of Computer Science, University of Lincoln, Lincoln LN6 7TS, United Kingdom
| | - P M Evans
- Centre for Vision Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - S Green
- School of Physics and Astronomy, University of Birmingham, Birmingham B25 2TT, United Kingdom
| | - S Manger
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - S Manolopoulos
- University Hospitals Coventry and Warwickshire NHS Trust, Coventry CV2 2DX, United Kingdom
| | - J Nieto-Camero
- iThemba LABS, P.O. Box 722, Somerset West 7129, South Africa
| | - D J Parker
- School of Physics and Astronomy, University of Birmingham, Birmingham B25 2TT, United Kingdom
| | - J Symons
- iThemba LABS, P.O. Box 722, Somerset West 7129, South Africa
| | - N M Allinson
- Laboratory of Vision Engineering, School of Computer Science, University of Lincoln, Lincoln LN6 7TS, United Kingdom
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17
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Wang P, Cammin J, Bisello F, Solberg TD, McDonough JE, Zhu TC, Menichelli D, Teo BKK. Proton computed tomography using a 1D silicon diode array. Med Phys 2016; 43:5758. [PMID: 27782709 DOI: 10.1118/1.4963221] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Proton radiography (PR) and proton computed tomography (PCT) can be used to measure proton stopping power directly. However, practical and cost effective proton imaging detectors are not widely available. In this study, the authors investigated the feasibility of proton imaging using a silicon diode array. METHODS A one-dimensional silicon diode detector array (1DSDA) was aligned with the central axis (CAX) of the proton beam. Polymethyl methacrylate (PMMA) slabs were used to find the correspondence between the water equivalent thickness (WET) and 1DSDA channel number. Two-dimensional proton radiographs were obtained by translation and rotation of a phantom relative to CAX while the proton nozzle and 1DSDA were kept stationary. A PCT image of one slice of the phantom was reconstructed using filtered backprojection. RESULTS PR and PCT images of the PMMA cube were successfully acquired using the 1DSDA. The WET of the phantom was measured using PR data. The resolution and maximum error in WET measurement are 2.0 and 1.5 mm, respectively. Structures down to 2.0 mm in size could be resolved completely. Reconstruction of a PCT image showed very good agreement with simulation. Limitations in spatial resolution are attributed to limited spatial sampling, beam collimation, and proton scatter. CONCLUSIONS The results demonstrate the feasibility of using silicon diode arrays for proton imaging. Such a device can potentially offer fast image acquisition and high spatial and energy resolution for PR and PCT.
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Affiliation(s)
- Peng Wang
- Texas Center for Proton Therapy, Irving, Texas 75063
| | - Jochen Cammin
- The College of Liberal and Professional Studies of the School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Francesca Bisello
- IBA Dosimetry GmbH, Schwarzenbruck 90592, Germany and Friedrich-Alexander University Erlangen-Nürnberg, Erlangen 91058, Germany
| | - Timothy D Solberg
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - James E McDonough
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Timothy C Zhu
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | | | - Boon-Keng Kevin Teo
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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Taylor J, Waltham C, Price T, Allinson N, Allport P, Casse G, Kacperek A, Manger S, Smith N, Tsurin I. A new silicon tracker for proton imaging and dosimetry. Nucl Instrum Methods Phys Res A 2016; 831:362-366. [PMID: 27667884 PMCID: PMC5002944 DOI: 10.1016/j.nima.2016.02.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
For many years, silicon micro-strip detectors have been successfully used as tracking detectors for particle and nuclear physics experiments. A new application of this technology is to the field of particle therapy where radiotherapy is carried out by use of charged particles such as protons or carbon ions. Such a treatment has been shown to have advantages over standard x-ray radiotherapy and as a result of this, many new centres offering particle therapy are currently under construction around the world today. The Proton Radiotherapy, Verification and Dosimetry Applications (PRaVDA) consortium are developing instrumentation for particle therapy based upon technology from high-energy physics. The characteristics of a new silicon micro-strip tracker for particle therapy will be presented. The array uses specifically designed, large area sensors with technology choices that follow closely those taken for the ATLAS experiment at the HL-LHC. These detectors will be arranged into four units each with three layers in an x-u-v configuration to be suitable for fast proton tracking with minimal ambiguities. The sensors will form a tracker capable of tracing the path of ~200 MeV protons entering and exiting a patient allowing a new mode of imaging known as proton computed tomography (pCT). This will aid the accurate delivery of treatment doses and in addition, the tracker will also be used to monitor the beam profile and total dose delivered during the high fluences used for treatment. We present here details of the design, construction and assembly of one of the four units that will make up the complete tracker along with its characterisation using radiation tests carried out using a 90Sr source in the laboratory and a 60 MeV proton beam at the Clatterbridge Cancer Centre.
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Affiliation(s)
- J.T. Taylor
- Department of Physics, University of Liverpool, Oxford Street, Liverpool L69 7ZE, UK
| | - C. Waltham
- Laboratory of Vision Engineering, School of Computer Science, University of Lincoln, Lincoln LN6 7TS, UK
| | - T. Price
- School of Physics and Astronomy, University of Birmingham, Birmingham B25 2TT, UK
| | - N.M. Allinson
- Laboratory of Vision Engineering, School of Computer Science, University of Lincoln, Lincoln LN6 7TS, UK
| | - P.P. Allport
- School of Physics and Astronomy, University of Birmingham, Birmingham B25 2TT, UK
| | - G.L. Casse
- Department of Physics, University of Liverpool, Oxford Street, Liverpool L69 7ZE, UK
| | - A. Kacperek
- Douglas Cyclotron, The Clatterbridge Cancer Centre NHS Foundation Trust, Clatterbridge Road, Bebington, Wirral CH63 4JY, UK
| | - S. Manger
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK
| | - N.A. Smith
- Department of Physics, University of Liverpool, Oxford Street, Liverpool L69 7ZE, UK
| | - I. Tsurin
- Department of Physics, University of Liverpool, Oxford Street, Liverpool L69 7ZE, UK
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19
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20
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Abstract
A novel approach to proton CT reconstruction using backprojection-then-filtering (BPF) is proposed. A list-mode algorithm is formulated accommodating non-linear proton paths. The analytical form is derived for the deblurring kernel necessary for the filtering step. Further, a finite matrix correction is derived to correct for the limited size of the backprojection matrix. High quantitative accuracy in relative stopping power is demonstrated (⩽0.1%) using Monte Carlo simulations. This accuracy makes the algorithm a promising candidate for future proton CT systems in proton therapy applications. For the purposes of reconstruction, each proton path in the object-of-interest was estimated based on a cubic spline fit to the proton entry and exit vectors. The superior spatial-resolution of the BPF method over the standard filtering-then-backprojection approach is demonstrated. As the BPF algorithm requires only one backprojection and filtering operation on a scan data set, it also offers computational advantages over an iterative reconstruction approach.
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Affiliation(s)
- G Poludniowski
- Centre for Vision Speech and Signal Processing, University of Surrey, Guildford, GU2 7XH, UK
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21
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Doolan PJ, Royle G, Gibson A, Lu HM, Prieels D, Bentefour EH. Dose ratio proton radiography using the proximal side of the Bragg peak. Med Phys 2015; 42:1871-83. [PMID: 25832077 DOI: 10.1118/1.4915492] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE In recent years, there has been a movement toward single-detector proton radiography, due to its potential ease of implementation within the clinical environment. One such single-detector technique is the dose ratio method in which the dose maps from two pristine Bragg peaks are recorded beyond the patient. To date, this has only been investigated on the distal side of the lower energy Bragg peak, due to the sharp falloff. The authors investigate the limits and applicability of the dose ratio method on the proximal side of the lower energy Bragg peak, which has the potential to allow a much wider range of water-equivalent thicknesses (WET) to be imaged. Comparisons are made with the use of the distal side of the Bragg peak. METHODS Using the analytical approximation for the Bragg peak, the authors generated theoretical dose ratio curves for a range of energy pairs, and then determined how an uncertainty in the dose ratio would translate to a spread in the WET estimate. By defining this spread as the accuracy one could achieve in the WET estimate, the authors were able to generate lookup graphs of the range on the proximal side of the Bragg peak that one could reliably use. These were dependent on the energy pair, noise level in the dose ratio image and the required accuracy in the WET. Using these lookup graphs, the authors investigated the applicability of the technique for a range of patient treatment sites. The authors validated the theoretical approach with experimental measurements using a complementary metal oxide semiconductor active pixel sensor (CMOS APS), by imaging a small sapphire sphere in a high energy proton beam. RESULTS Provided the noise level in the dose ratio image was 1% or less, a larger spread of WETs could be imaged using the proximal side of the Bragg peak (max 5.31 cm) compared to the distal side (max 2.42 cm). In simulation, it was found that, for a pediatric brain, it is possible to use the technique to image a region with a square field equivalent size of 7.6 cm(2), for a required accuracy in the WET of 3 mm and a 1% noise level in the dose ratio image. The technique showed limited applicability for other patient sites. The CMOS APS demonstrated a good accuracy, with a root-mean-square-error of 1.6 mm WET. The noise in the measured images was found to be σ = 1.2% (standard deviation) and theoretical predictions with a 1.96σ noise level showed good agreement with the measured errors. CONCLUSIONS After validating the theoretical approach with measurements, the authors have shown that the use of the proximal side of the Bragg peak when performing dose ratio imaging is feasible, and allows for a wider dynamic range than when using the distal side. The dynamic range available increases as the demand on the accuracy of the WET decreases. The technique can only be applied to clinical sites with small maximum WETs such as for pediatric brains.
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Affiliation(s)
- P J Doolan
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, United Kingdom
| | - G Royle
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, United Kingdom
| | - A Gibson
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, United Kingdom
| | - H-M Lu
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - D Prieels
- Ion Beam Applications (IBA), 3 Chemin du Cyclotron, Louvain la Neuve B-1348, Belgium
| | - E H Bentefour
- Ion Beam Applications (IBA), 3 Chemin du Cyclotron, Louvain la Neuve B-1348, Belgium
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22
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Abstract
Proton radiography and tomography have long promised benefit for proton therapy. Their first suggestion was in the early 1960s and the first published proton radiographs and CT images appeared in the late 1960s and 1970s, respectively. More than just providing anatomical images, proton transmission imaging provides the potential for the more accurate estimation of stopping-power ratio inside a patient and hence improved treatment planning and verification. With the recent explosion in growth of clinical proton therapy facilities, the time is perhaps ripe for the imaging modality to come to the fore. Yet many technical challenges remain to be solved before proton CT scanners become commonplace in the clinic. Research and development in this field is currently more active than at any time with several prototype designs emerging. This review introduces the principles of proton radiography and tomography, their historical developments, the raft of modern prototype systems and the primary design issues.
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Affiliation(s)
- G Poludniowski
- 1 Centre for Vision Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK.,2 Department of Medical Physics, Karolinska University Hospital, Stockholm, Sweden
| | - N M Allinson
- 3 Laboratory of Vision Engineering, School of Computer Science, University of Lincoln, Brayford Pool, Lincoln, UK
| | - P M Evans
- 1 Centre for Vision Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK
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Esposito M, Anaxagoras T, Evans P, Green S, Manolopoulos S, Nieto-Camero J, Parker D, Poludniowski G, Price T, Waltham C, Allinson N. CMOS Active Pixel Sensors as energy-range detectors for proton Computed Tomography. J Instrum 2015; 10:C06001. [PMID: 29225666 PMCID: PMC5718318 DOI: 10.1088/1748-0221/10/06/c06001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Since the first proof of concept in the early 70s, a number of technologies has been proposed to perform proton CT (pCT), as a means of mapping tissue stopping power for accurate treatment planning in proton therapy. Previous prototypes of energy-range detectors for pCT have been mainly based on the use of scintillator-based calorimeters, to measure proton residual energy after passing through the patient. However, such an approach is limited by the need for only a single proton passing through the energy-range detector in a read-out cycle. A novel approach to this problem could be the use of pixelated detectors, where the independent read-out of each pixel allows to measure simultaneously the residual energy of a number of protons in the same read-out cycle, facilitating a faster and more efficient pCT scan. This paper investigates the suitability of CMOS Active Pixel Sensors (APSs) to track individual protons as they go through a number of CMOS layers, forming an energy-range telescope. Measurements performed at the iThemba Laboratories will be presented and analysed in terms of correlation, to confirm capability of proton tracking for CMOS APSs.
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Affiliation(s)
- M. Esposito
- School of Computer Science, University of Lincoln, Lincoln, LN6 7TS, U.K
- Centre for Vision, Speech and Signal Processing, University of Surrey, Guildford GU2 7XH, U.K
| | - T. Anaxagoras
- ISDI Ltd (Image Sensor Design and Innovation), Oxford, OX4 1YZ, U.K
| | - P.M. Evans
- Centre for Vision, Speech and Signal Processing, University of Surrey, Guildford GU2 7XH, U.K
| | - S. Green
- School of Physics and Astronomy, University of Birmingham, Birmingham, B152TT, U.K
- Hall Edwards Radiotherapy Research Group, University Hospital Birmingham NHS Foundation Trust, Birmingham, B15 2TH, U.K
| | - S. Manolopoulos
- University Hospitals Coventry and Warwickshire NHS Trust, Coventry, CV2 2DX, U.K
| | | | - D.J. Parker
- School of Physics and Astronomy, University of Birmingham, Birmingham, B152TT, U.K
| | - G. Poludniowski
- Centre for Vision, Speech and Signal Processing, University of Surrey, Guildford GU2 7XH, U.K
| | - T. Price
- School of Physics and Astronomy, University of Birmingham, Birmingham, B152TT, U.K
| | - C. Waltham
- School of Computer Science, University of Lincoln, Lincoln, LN6 7TS, U.K
| | - N.M. Allinson
- School of Computer Science, University of Lincoln, Lincoln, LN6 7TS, U.K
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24
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Jones B. Towards Achieving the Full Clinical Potential of Proton Therapy by Inclusion of LET and RBE Models. Cancers (Basel) 2015; 7:460-80. [PMID: 25790470 PMCID: PMC4381269 DOI: 10.3390/cancers7010460] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 01/19/2015] [Accepted: 03/06/2015] [Indexed: 12/13/2022] Open
Abstract
Despite increasing use of proton therapy (PBT), several systematic literature reviews show limited gains in clinical outcomes, with publications mostly devoted to recent technical developments. The lack of randomised control studies has also hampered progress in the acceptance of PBT by many oncologists and policy makers. There remain two important uncertainties associated with PBT, namely: (1) accuracy and reproducibility of Bragg peak position (BPP); and (2) imprecise knowledge of the relative biological effect (RBE) for different tissues and tumours, and at different doses. Incorrect BPP will change dose, linear energy transfer (LET) and RBE, with risks of reduced tumour control and enhanced toxicity. These interrelationships are discussed qualitatively with respect to the ICRU target volume definitions. The internationally accepted proton RBE of 1.1 was based on assays and dose ranges unlikely to reveal the complete range of RBE in the human body. RBE values are not known for human (or animal) brain, spine, kidney, liver, intestine, etc. A simple efficiency model for estimating proton RBE values is described, based on data of Belli et al. and other authors, which allows linear increases in α and β with LET, with a gradient estimated using a saturation model from the low LET α and β radiosensitivity parameter input values, and decreasing RBE with increasing dose. To improve outcomes, 3-D dose-LET-RBE and bio-effectiveness maps are required. Validation experiments are indicated in relevant tissues. Randomised clinical studies that test the invariant 1.1 RBE allocation against higher values in late reacting tissues, and lower tumour RBE values in the case of radiosensitive tumours, are also indicated.
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Affiliation(s)
- Bleddyn Jones
- Gray Laboratory, CRUK/MRC Oxford Oncology Institute, The University of Oxford, ORCRB-Roosevelt Drive, Oxford OX3 7DQ, UK.
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25
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Doolan PJ, Testa M, Sharp G, Bentefour EH, Royle G, Lu HM. Patient-specific stopping power calibration for proton therapy planning based on single-detector proton radiography. Phys Med Biol 2015; 60:1901-17. [DOI: 10.1088/0031-9155/60/5/1901] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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