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Lee H, Cheon BW, Feld JW, Grogg K, Perl J, Ramos-Méndez JA, Faddegon B, Min CH, Paganetti H, Schuemann J. TOPAS-imaging: extensions to the TOPAS simulation toolkit for medical imaging systems. Phys Med Biol 2023; 68:10.1088/1361-6560/acc565. [PMID: 36930985 PMCID: PMC10164408 DOI: 10.1088/1361-6560/acc565] [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: 11/30/2022] [Accepted: 03/17/2023] [Indexed: 03/19/2023]
Abstract
Objective. The TOol for PArticle Simulation (TOPAS) is a Geant4-based Monte Carlo software application that has been used for both research and clinical studies in medical physics. So far, most users of TOPAS have focused on radiotherapy-related studies, such as modeling radiation therapy delivery systems or patient dose calculation. Here, we present the first set of TOPAS extensions to make it easier for TOPAS users to model medical imaging systems.Approach. We used the extension system of TOPAS to implement pre-built, user-configurable geometry components such as detectors (e.g. flat-panel and multi-planar detectors) for various imaging modalities and pre-built, user-configurable scorers for medical imaging systems (e.g. digitizer chain).Main results. We developed a flexible set of extensions that can be adapted to solve research questions for a variety of imaging modalities. We then utilized these extensions to model specific examples of cone-beam CT (CBCT), positron emission tomography (PET), and prompt gamma (PG) systems. The first of these new geometry components, the FlatImager, was used to model example CBCT and PG systems. Detected signals were accumulated in each detector pixel to obtain the intensity of x-rays penetrating objects or prompt gammas from proton-nuclear interaction. The second of these new geometry components, the RingImager, was used to model an example PET system. Positron-electron annihilation signals were recorded in crystals of the RingImager and coincidences were detected. The simulated data were processed using corresponding post-processing algorithms for each modality and obtained results in good agreement with the expected true signals or experimental measurement.Significance. The newly developed extension is a first step to making it easier for TOPAS users to build and simulate medical imaging systems. Together with existing TOPAS tools, this extension can help integrate medical imaging systems with radiotherapy simulations for image-guided radiotherapy.
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Affiliation(s)
- Hoyeon Lee
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States of America
| | - Bo-Wi Cheon
- Department of Radiation Convergence Engineering, Yonsei University, Wonju, Gangwon-do 26493, Republic of Korea
| | - Joseph W Feld
- Electrical Engineering and Computer Science Department, Massachusetts Institute of Technology, Cambridge, MA 02139, United States of America
| | - Kira Grogg
- The Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States of America
| | - Joseph Perl
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025 United States of America
| | - José A Ramos-Méndez
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA 94115 United States of America
| | - Bruce Faddegon
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA 94115 United States of America
| | - Chul Hee Min
- Department of Radiation Convergence Engineering, Yonsei University, Wonju, Gangwon-do 26493, Republic of Korea
| | - Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States of America
| | - Jan Schuemann
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States of America
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Tashima H, Nishina T, Takyu S, Nishikido F, Suga M, Yamaya T. Optimum selection for multi-interaction events in Compton-PET hybrid reconstruction: a Monte Carlo study. Radiol Phys Technol 2023; 16:254-261. [PMID: 36943646 DOI: 10.1007/s12194-023-00714-5] [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: 07/04/2022] [Revised: 03/13/2023] [Accepted: 03/13/2023] [Indexed: 03/23/2023]
Abstract
In Compton PET, that has a scatterer inserted inside a PET ring, there are multi-interaction events that can be treated as both PET and Compton events. A PET event from multi-interaction events that include a Compton event and a photoelectric absorption event or two Compton events can be extracted by applying a PET recovery method. In this study, we aimed to establish a method to maximize image quality by utilizing such redundant events. We conducted brain-scale Monte Carlo simulations of a C-shaped Compton-PET geometry and a whole gamma imaging (WGI) geometry. Images were reconstructed by a hybrid image reconstruction method combining both PET and Compton events. The result showed that the spatial resolution was improved when treated as PET events while keeping the noise level. The effect of improvement was more significant in WGI than in C-shaped Compton PET because the number of events recovered as PET events having more accurate spatial information was much larger in WGI. When the PET-recovered multi-interaction events were also included as Compton events in the hybrid reconstruction, we did not observe any improvement in image quality, while the number of used events was largest. The results suggested that treating events as PET events exclusively was better for image quality.
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Affiliation(s)
- Hideaki Tashima
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba, 263-8555, Japan.
| | - Takumi Nishina
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba, 263-8555, Japan
- Medical Engineering Course, Graduate School of Science and Engineering, Chiba University, 1-33, Yayoicho, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan
| | - Sodai Takyu
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba, 263-8555, Japan
| | - Fumihiko Nishikido
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba, 263-8555, Japan
| | - Mikio Suga
- Medical Engineering Course, Graduate School of Science and Engineering, Chiba University, 1-33, Yayoicho, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan
- Center for Frontier Medical Engineering, Chiba University, 1-33, Yayoicho, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan
| | - Taiga Yamaya
- National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-ku, Chiba-shi, Chiba, 263-8555, Japan
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Du J, Jones T. Technical opportunities and challenges in developing total-body PET scanners for mice and rats. EJNMMI Phys 2023; 10:2. [PMID: 36592266 PMCID: PMC9807733 DOI: 10.1186/s40658-022-00523-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 12/20/2022] [Indexed: 01/03/2023] Open
Abstract
Positron emission tomography (PET) is the most sensitive in vivo molecular imaging technique available. Small animal PET has been widely used in studying pharmaceutical biodistribution and disease progression over time by imaging a wide range of biological processes. However, it remains true that almost all small animal PET studies using mouse or rat as preclinical models are either limited by the spatial resolution or the sensitivity (especially for dynamic studies), or both, reducing the quantitative accuracy and quantitative precision of the results. Total-body small animal PET scanners, which have axial lengths longer than the nose-to-anus length of the mouse/rat and can provide high sensitivity across the entire body of mouse/rat, can realize new opportunities for small animal PET. This article aims to discuss the technical opportunities and challenges in developing total-body small animal PET scanners for mice and rats.
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Affiliation(s)
- Junwei Du
- grid.27860.3b0000 0004 1936 9684Department of Biomedical Engineering, University of California at Davis, Davis, CA 95616 USA
| | - Terry Jones
- grid.27860.3b0000 0004 1936 9684Department of Radiology, University of California at Davis, Davis, CA 95616 USA
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Ungerer A, Staufer T, Schmutzler O, Körnig C, Rothkamm K, Grüner F. X-ray-Fluorescence Imaging for In Vivo Detection of Gold-Nanoparticle-Labeled Immune Cells: A GEANT4 Based Feasibility Study. Cancers (Basel) 2021; 13:5759. [PMID: 34830917 PMCID: PMC8616134 DOI: 10.3390/cancers13225759] [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: 10/27/2021] [Revised: 11/12/2021] [Accepted: 11/15/2021] [Indexed: 12/21/2022] Open
Abstract
The growing field of cellular therapies in regenerative medicine and oncology calls for more refined diagnostic tools that are able to investigate and monitor the function and success of said therapies. X-ray Fluorescence Imaging (XFI) can be applied for molecular imaging with nanoparticles, such as gold nanoparticles (GNPs), which can be used in immune cell tracking. We present a Monte Carlo simulation study on the sensitivity of detection and associated radiation dose estimations in an idealized setup of XFI in human-sized objects. Our findings demonstrate the practicability of XFI in human-sized objects, as immune cell tracking with a minimum detection limit of 4.4 × 105 cells or 0.86 μg gold in a cubic volume of 1.78 mm3 can be achieved. Therefore, our results show that the current technological developments form a good basis for high sensitivity XFI.
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Affiliation(s)
- Arthur Ungerer
- University Medical Center Hamburg-Eppendorf, Department of Radiotherapy and Radiation Oncology, Medical Faculty, University of Hamburg, Martinistraße 52, 20246 Hamburg, Germany; (A.U.); (K.R.)
- Universität Hamburg and Center for Free-Electron Laser Science (CFEL), Institute for Experimental Physics, Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany; (T.S.); (O.S.); (C.K.)
| | - Theresa Staufer
- Universität Hamburg and Center for Free-Electron Laser Science (CFEL), Institute for Experimental Physics, Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany; (T.S.); (O.S.); (C.K.)
| | - Oliver Schmutzler
- Universität Hamburg and Center for Free-Electron Laser Science (CFEL), Institute for Experimental Physics, Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany; (T.S.); (O.S.); (C.K.)
| | - Christian Körnig
- Universität Hamburg and Center for Free-Electron Laser Science (CFEL), Institute for Experimental Physics, Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany; (T.S.); (O.S.); (C.K.)
| | - Kai Rothkamm
- University Medical Center Hamburg-Eppendorf, Department of Radiotherapy and Radiation Oncology, Medical Faculty, University of Hamburg, Martinistraße 52, 20246 Hamburg, Germany; (A.U.); (K.R.)
| | - Florian Grüner
- Universität Hamburg and Center for Free-Electron Laser Science (CFEL), Institute for Experimental Physics, Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany; (T.S.); (O.S.); (C.K.)
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Jaliparthi G, Martone PF, Stolin AV, Raylman RR. Deep residual-convolutional neural networks for event positioning in a monolithic annular PET scanner. Phys Med Biol 2021; 66. [PMID: 34153950 DOI: 10.1088/1361-6560/ac0d0c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 06/21/2021] [Indexed: 11/12/2022]
Abstract
PET scanners based on monolithic pieces of scintillator can potentially produce superior performance characteristics (high spatial resolution and detection sensitivity, for example) compared to conventional PET scanners. Consequently, we initiated development of a preclinical PET system based on a single 7.2 cm long annulus of LYSO, called AnnPET. While this system could facilitate creation of high-quality images, its unique geometry results in optics that can complicate estimation of event positioning in the detector. To address this challenge, we evaluated deep-residual convolutional neural networks (DR-CNN) to estimate the three-dimensional position of annihilation photon interactions. Monte Carlo simulations of the AnnPET scanner were used to replicate the physics, including optics, of the scanner. It was determined that a ten-layer-DR-CNN was most suited to application with AnnPET. The errors between known event positions, and those estimated by this network and those calculated with the commonly used center-of-mass algorithm (COM) were used to assess performance. The mean absolute errors (MAE) for the ten-layer-DR-CNN-based event positions were 0.54 mm, 0.42 mm and 0.45 mm along thex(axial)-,y(transaxial)- andz- (depth-of-interaction) axes, respectively. For COM estimates, the MAEs were 1.22 mm, 1.04 mm and 2.79 mm in thex-,y- andz-directions, respectively. Reconstruction of the network-estimated data with the 3D-FBP algorithm (5 mm source offset) yielded spatial resolutions (full-width-at-half-maximum (FWHM)) of 0.8 mm (radial), 0.7 mm (tangential) and 0.71 mm (axial). Reconstruction of the COM-derived data yielded spatial resolutions (FWHM) of 1.15 mm (radial), 0.96 mm (tangential) and 1.14 mm (axial). These findings demonstrated that use of a ten-layer-DR-CNN with a PET scanner based on a monolithic annulus of scintillator has the potential to produce excellent performance compared to standard analytical methods.
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Affiliation(s)
- Gangadhar Jaliparthi
- Center for Advanced Imaging, Department of Radiology, School of Medicine, West Virginia University, Morgantown, WV, United States of America
| | - Peter F Martone
- Center for Advanced Imaging, Department of Radiology, School of Medicine, West Virginia University, Morgantown, WV, United States of America
| | - Alexander V Stolin
- Center for Advanced Imaging, Department of Radiology, School of Medicine, West Virginia University, Morgantown, WV, United States of America
| | - Raymond R Raylman
- Center for Advanced Imaging, Department of Radiology, School of Medicine, West Virginia University, Morgantown, WV, United States of America
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