Pub Date : 2024-11-13DOI: 10.1109/TRPMS.2024.3497774
Haibo Wang;Jiahao Xie;Jinyi Qi;Simon R. Cherry;Junwei Du
Positron emission tomography (PET) detectors suffer from time-walk when the leading edge discriminator is employed for timing pick-off as well as a timing-shift when thick crystals are utilized due to the depth-of-interaction (DOI) effect. In this study, a combined time-walk and timing-shift correction method was proposed for dual-ended readout PET detectors. To evaluate the proposed method, a pair of dual-ended readout PET detectors was constructed. Each detector was based on two Hamamatsu S14161-3050-08 silicon photomultiplier (SiPM) arrays coupled to both ends of an $8times 8$ arrays of $3.1times 3.1times 20~{mathrm { mm}}^{3}$ lutetium-yttrium oxyorthosilicate crystals with a 3.2-mm pitch. By employing the relationship between the energies and detected time differences of events, the time-walk and timing-shift were effectively corrected. The coincidence time resolution of the two detectors improved from $260.7~pm ~1.0$ ps to $229.4~pm ~1.0$ ps when a 400–650 keV energy window was used to select events. These results demonstrate the effectiveness of the proposed time-walk and timing-shift correction method.
{"title":"A Time-Walk and Timing-Shift Correction Method for Dual-Ended Readout TOF-DOI PET Detectors","authors":"Haibo Wang;Jiahao Xie;Jinyi Qi;Simon R. Cherry;Junwei Du","doi":"10.1109/TRPMS.2024.3497774","DOIUrl":"https://doi.org/10.1109/TRPMS.2024.3497774","url":null,"abstract":"Positron emission tomography (PET) detectors suffer from time-walk when the leading edge discriminator is employed for timing pick-off as well as a timing-shift when thick crystals are utilized due to the depth-of-interaction (DOI) effect. In this study, a combined time-walk and timing-shift correction method was proposed for dual-ended readout PET detectors. To evaluate the proposed method, a pair of dual-ended readout PET detectors was constructed. Each detector was based on two Hamamatsu S14161-3050-08 silicon photomultiplier (SiPM) arrays coupled to both ends of an <inline-formula> <tex-math>$8times 8$ </tex-math></inline-formula> arrays of <inline-formula> <tex-math>$3.1times 3.1times 20~{mathrm { mm}}^{3}$ </tex-math></inline-formula> lutetium-yttrium oxyorthosilicate crystals with a 3.2-mm pitch. By employing the relationship between the energies and detected time differences of events, the time-walk and timing-shift were effectively corrected. The coincidence time resolution of the two detectors improved from <inline-formula> <tex-math>$260.7~pm ~1.0$ </tex-math></inline-formula> ps to <inline-formula> <tex-math>$229.4~pm ~1.0$ </tex-math></inline-formula> ps when a 400–650 keV energy window was used to select events. These results demonstrate the effectiveness of the proposed time-walk and timing-shift correction method.","PeriodicalId":46807,"journal":{"name":"IEEE Transactions on Radiation and Plasma Medical Sciences","volume":"9 3","pages":"277-283"},"PeriodicalIF":4.6,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143553294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-13DOI: 10.1109/TRPMS.2024.3495219
Ang Li;Bingxuan Li;Lei Fang;Xiaoyun Zhou;Qingguo Xie;Peng Xiao
Energy-based scatter estimation methods have illustrated promising results in recent literature. Accurate estimation of energy probability density function of scattered photons (PDF-SC) is essential for precise scatter estimation and avoiding bias in reconstructed images. This article presents a novel method, referred to as energy spectra modification (ESM), to precisely estimate position-dependent local PDF-SC, which improves the accuracy of scatter estimation. ESM involves an iterative process to deblur local energy spectra, with the starting point constructed using an initial PDF-SC derived from global energy spectra. The scattered component of the deblurred energy spectrum is reblurred and normalized to estimate the local PDF-SC. We validated this approach through Monte Carlo simulations using a bladder phantom, an image quality phantom, and a cylindrical phantom. Comparative analyses were conducted against the traditional method employing global PDF-SC, a recent advancement, and the single scatter simulation method. The results demonstrated that our method effectively reduced activity bias of the global PDF-SC approach across various energy resolutions, windows, target size, and count levels. It achieved this with a comparable computational load and without hyperparameter modification.
{"title":"Enhancing Energy-Based Scatter Estimation Using Energy Spectra Modification in PET","authors":"Ang Li;Bingxuan Li;Lei Fang;Xiaoyun Zhou;Qingguo Xie;Peng Xiao","doi":"10.1109/TRPMS.2024.3495219","DOIUrl":"https://doi.org/10.1109/TRPMS.2024.3495219","url":null,"abstract":"Energy-based scatter estimation methods have illustrated promising results in recent literature. Accurate estimation of energy probability density function of scattered photons (PDF-SC) is essential for precise scatter estimation and avoiding bias in reconstructed images. This article presents a novel method, referred to as energy spectra modification (ESM), to precisely estimate position-dependent local PDF-SC, which improves the accuracy of scatter estimation. ESM involves an iterative process to deblur local energy spectra, with the starting point constructed using an initial PDF-SC derived from global energy spectra. The scattered component of the deblurred energy spectrum is reblurred and normalized to estimate the local PDF-SC. We validated this approach through Monte Carlo simulations using a bladder phantom, an image quality phantom, and a cylindrical phantom. Comparative analyses were conducted against the traditional method employing global PDF-SC, a recent advancement, and the single scatter simulation method. The results demonstrated that our method effectively reduced activity bias of the global PDF-SC approach across various energy resolutions, windows, target size, and count levels. It achieved this with a comparable computational load and without hyperparameter modification.","PeriodicalId":46807,"journal":{"name":"IEEE Transactions on Radiation and Plasma Medical Sciences","volume":"9 3","pages":"347-361"},"PeriodicalIF":4.6,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143553286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-06DOI: 10.1109/TRPMS.2024.3492674
T. Ferri;F. Rosellini;A. Caracciolo;G. Borghi;M. Carminati;F. Camera;A. Giaz;C. Fiorini
Monolithic gamma-ray detectors can be used in single photon emission computed tomography systems for monitoring the delivered dose during boron neutron capture therapy treatments. Gamma-ray hit localization in thick monolithic scintillator crystals is a challenging task due to internal reflections and Compton scattering. Existing methods like the center of gravity (CoG) are susceptible to reconstruction uncertainties at the crystal edges, while approaches, including nonlinear analytical and statistical models, such as the maximum-likelihood, require significant computational resources. Artificial neural networks (ANNs) offer significant improvements in terms of accuracy and computational speed. In this study, we develop a supervised ANN regression algorithm for real-time position reconstruction in a thick square lanthanum bromide crystal [LaBr$_{3}(text {Ce}+text {Sr})$ ] with $5, text {cm}times 5,text {cm}times 2,text {cm}$ dimensions, coupled with an $8times 8$ matrix of silicon photomultipliers. The implemented neural network was trained and tested using calibration data acquired irradiating the crystal with a collimated 137Cs source (pencil-beam irradiation). The detector in combination with the ANN model achieves a positioning accuracy for single-gamma-ray events of approximately 2.6 mm in the central region, evaluated as the full width at half maximum (FWHM) of the prediction error distribution, slightly worsening toward the edges. The imaging capabilities of the detector in combination with a channel-edge pinhole collimator were then evaluated by acquiring images of a movable uncollimated 137Cs point source. The source was shifted in nine different positions at 3 mm distance from each other and the resolution of the system was evaluated fitting the images with a Gaussian curve. An image spatial resolution of around 8 mm FWHM was obtained, dominated as expected by the collimator geometry, with an accuracy of 0.7 mm in estimating the position of the point source.
{"title":"Gamma-Ray Position-of-Interaction Estimation in a Thick Monolithic LaBr3 Detector Using Artificial Neural Networks","authors":"T. Ferri;F. Rosellini;A. Caracciolo;G. Borghi;M. Carminati;F. Camera;A. Giaz;C. Fiorini","doi":"10.1109/TRPMS.2024.3492674","DOIUrl":"https://doi.org/10.1109/TRPMS.2024.3492674","url":null,"abstract":"Monolithic gamma-ray detectors can be used in single photon emission computed tomography systems for monitoring the delivered dose during boron neutron capture therapy treatments. Gamma-ray hit localization in thick monolithic scintillator crystals is a challenging task due to internal reflections and Compton scattering. Existing methods like the center of gravity (CoG) are susceptible to reconstruction uncertainties at the crystal edges, while approaches, including nonlinear analytical and statistical models, such as the maximum-likelihood, require significant computational resources. Artificial neural networks (ANNs) offer significant improvements in terms of accuracy and computational speed. In this study, we develop a supervised ANN regression algorithm for real-time position reconstruction in a thick square lanthanum bromide crystal [LaBr<inline-formula> <tex-math>$_{3}(text {Ce}+text {Sr})$ </tex-math></inline-formula>] with <inline-formula> <tex-math>$5, text {cm}times 5,text {cm}times 2,text {cm}$ </tex-math></inline-formula> dimensions, coupled with an <inline-formula> <tex-math>$8times 8$ </tex-math></inline-formula> matrix of silicon photomultipliers. The implemented neural network was trained and tested using calibration data acquired irradiating the crystal with a collimated 137Cs source (pencil-beam irradiation). The detector in combination with the ANN model achieves a positioning accuracy for single-gamma-ray events of approximately 2.6 mm in the central region, evaluated as the full width at half maximum (FWHM) of the prediction error distribution, slightly worsening toward the edges. The imaging capabilities of the detector in combination with a channel-edge pinhole collimator were then evaluated by acquiring images of a movable uncollimated 137Cs point source. The source was shifted in nine different positions at 3 mm distance from each other and the resolution of the system was evaluated fitting the images with a Gaussian curve. An image spatial resolution of around 8 mm FWHM was obtained, dominated as expected by the collimator geometry, with an accuracy of 0.7 mm in estimating the position of the point source.","PeriodicalId":46807,"journal":{"name":"IEEE Transactions on Radiation and Plasma Medical Sciences","volume":"9 3","pages":"284-295"},"PeriodicalIF":4.6,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10745622","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143553301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-05DOI: 10.1109/TRPMS.2024.3475531
{"title":"IEEE Transactions on Radiation and Plasma Medical Sciences Publication Information","authors":"","doi":"10.1109/TRPMS.2024.3475531","DOIUrl":"https://doi.org/10.1109/TRPMS.2024.3475531","url":null,"abstract":"","PeriodicalId":46807,"journal":{"name":"IEEE Transactions on Radiation and Plasma Medical Sciences","volume":"8 8","pages":"C3-C3"},"PeriodicalIF":4.6,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10744627","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142587633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-05DOI: 10.1109/TRPMS.2024.3475533
{"title":"IEEE Transactions on Radiation and Plasma Medical Sciences Information for Authors","authors":"","doi":"10.1109/TRPMS.2024.3475533","DOIUrl":"https://doi.org/10.1109/TRPMS.2024.3475533","url":null,"abstract":"","PeriodicalId":46807,"journal":{"name":"IEEE Transactions on Radiation and Plasma Medical Sciences","volume":"8 8","pages":"C2-C2"},"PeriodicalIF":4.6,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10744626","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142587518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-04DOI: 10.1109/TRPMS.2024.3483233
Ezzat Elmoujarkach;Steven Seeger;Luise Morgner;Fabian Schmidt;Julia G. Mannheim;Christian L. Schmidt;Magdalena Rafecas
This study explores the potential of digital light processing to 3-D print radioactive phantoms for high-resolution positron emission tomography (PET). Using a slightly modified desktop 3-D printer and mixtures of 18F-FDG (T1/2: 109.8 min) and photopolymer resin, we have printed standardized and custom radioactive objects designed for ultrahigh-resolution PET, also as a first step toward complex geometries. The phantoms were: a flood source to assess uniformity, a two-point phantom for spatial resolution assessment, a multiline phantom for validating submillimeter printing resolution, a fish-like phantom with different activity concentrations, and a 50%-downscaled micro-PET image quality phantom (National Electrical Manufacturers Association NU 4-2008). Positron range effects were examined on the latter using a removable cover. The evaluation relied on planar images from a phosphor imager and tomographic images from a commercial small animal PET scanner. We were able to print radioactive uniform distributions with relative standard deviation below 4.5% and structures as small as 0.3 mm. Our two-point phantom outperformed a commercial one in terms of peak difference (6% versus 72%) and peak-to-valley ratio (75.3 versus 14.1). The fish-like phantom shows that printing hot regions and air cavities onto a uniform background is feasible. Future steps include using longer-lived radionuclides like 89Zr and 22Na.
{"title":"Dedicated 3D-Printed Radioactive Phantoms With ¹⁸F-FDG for Ultrahigh-Resolution PET","authors":"Ezzat Elmoujarkach;Steven Seeger;Luise Morgner;Fabian Schmidt;Julia G. Mannheim;Christian L. Schmidt;Magdalena Rafecas","doi":"10.1109/TRPMS.2024.3483233","DOIUrl":"https://doi.org/10.1109/TRPMS.2024.3483233","url":null,"abstract":"This study explores the potential of digital light processing to 3-D print radioactive phantoms for high-resolution positron emission tomography (PET). Using a slightly modified desktop 3-D printer and mixtures of 18F-FDG (T1/2: 109.8 min) and photopolymer resin, we have printed standardized and custom radioactive objects designed for ultrahigh-resolution PET, also as a first step toward complex geometries. The phantoms were: a flood source to assess uniformity, a two-point phantom for spatial resolution assessment, a multiline phantom for validating submillimeter printing resolution, a fish-like phantom with different activity concentrations, and a 50%-downscaled micro-PET image quality phantom (National Electrical Manufacturers Association NU 4-2008). Positron range effects were examined on the latter using a removable cover. The evaluation relied on planar images from a phosphor imager and tomographic images from a commercial small animal PET scanner. We were able to print radioactive uniform distributions with relative standard deviation below 4.5% and structures as small as 0.3 mm. Our two-point phantom outperformed a commercial one in terms of peak difference (6% versus 72%) and peak-to-valley ratio (75.3 versus 14.1). The fish-like phantom shows that printing hot regions and air cavities onto a uniform background is feasible. Future steps include using longer-lived radionuclides like 89Zr and 22Na.","PeriodicalId":46807,"journal":{"name":"IEEE Transactions on Radiation and Plasma Medical Sciences","volume":"9 3","pages":"362-371"},"PeriodicalIF":4.6,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10742298","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143553287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-31DOI: 10.1109/TRPMS.2024.3487359
Nicolaus Kratochwil;Nathaniel Kaneshige;Giulia Terragni;Roberto Cala;Jared Schott;Edgar van Loef;Lakshmi Soundara Pandian;Emilie Roncali;Jaroslaw Glodo;Etiennette Auffray;Gerard Ariño-Estrada
The material requirements for gamma-ray detectors for medical imaging applications are multifold and sensitivity is often overlooked. High effective atomic number (Z$_{text {eff}}$ ) Cherenkov radiators have raised the attention in the community due to their potential for harvesting prompt photons. A material with one of the highest Zeff and thus short gamma-ray attenuation length is thallium chloride (TlCl). By doping TlCl with beryllium (Be) or iodine (I), it becomes a scintillator and therefore produces scintillation photons upon gamma-ray interaction on the top of the prompt Cherenkov luminescence. The scintillation response of TlCl:Be,I is investigated in terms of intensity, energy resolution, kinetics, and timing capability with and without energy discrimination. The ratio of prompt to slow scintillation photons is used to derive the intrinsic number of produced Cherenkov photons and compared with analytic calculations avoiding complex Monte Carlo simulations. The experimentally determined number of Cherenkov photons upon 511 keV gamma excitation of $17.9~pm ~4.6$ photons is in line with our simple calculations yielding 14.5 photons. We observe three scintillation decay time components with an effective decay time of 60 ns. The scintillation light yield of 0.9 ph/keV is sufficient to discriminate events with low energy deposition in the crystal which is used to improve the measured coincidence time resolution from 360-ps FWHM without energy selection down to 235-ps after energy discrimination and time walk correction for 2.8-mm thick TlCl:Be,I crystals, and from 580 to 402 ps for 15.2-mm thick ones. Already with the first generation of doped TlCl encouraging timing capability close to other materials with lower effective atomic number has been achieved.
{"title":"TlCl:Be,I: A High Sensitivity Scintillation and Cherenkov Radiator for TOF-PET","authors":"Nicolaus Kratochwil;Nathaniel Kaneshige;Giulia Terragni;Roberto Cala;Jared Schott;Edgar van Loef;Lakshmi Soundara Pandian;Emilie Roncali;Jaroslaw Glodo;Etiennette Auffray;Gerard Ariño-Estrada","doi":"10.1109/TRPMS.2024.3487359","DOIUrl":"https://doi.org/10.1109/TRPMS.2024.3487359","url":null,"abstract":"The material requirements for gamma-ray detectors for medical imaging applications are multifold and sensitivity is often overlooked. High effective atomic number (Z<inline-formula> <tex-math>$_{text {eff}}$ </tex-math></inline-formula>) Cherenkov radiators have raised the attention in the community due to their potential for harvesting prompt photons. A material with one of the highest Zeff and thus short gamma-ray attenuation length is thallium chloride (TlCl). By doping TlCl with beryllium (Be) or iodine (I), it becomes a scintillator and therefore produces scintillation photons upon gamma-ray interaction on the top of the prompt Cherenkov luminescence. The scintillation response of TlCl:Be,I is investigated in terms of intensity, energy resolution, kinetics, and timing capability with and without energy discrimination. The ratio of prompt to slow scintillation photons is used to derive the intrinsic number of produced Cherenkov photons and compared with analytic calculations avoiding complex Monte Carlo simulations. The experimentally determined number of Cherenkov photons upon 511 keV gamma excitation of <inline-formula> <tex-math>$17.9~pm ~4.6$ </tex-math></inline-formula> photons is in line with our simple calculations yielding 14.5 photons. We observe three scintillation decay time components with an effective decay time of 60 ns. The scintillation light yield of 0.9 ph/keV is sufficient to discriminate events with low energy deposition in the crystal which is used to improve the measured coincidence time resolution from 360-ps FWHM without energy selection down to 235-ps after energy discrimination and time walk correction for 2.8-mm thick TlCl:Be,I crystals, and from 580 to 402 ps for 15.2-mm thick ones. Already with the first generation of doped TlCl encouraging timing capability close to other materials with lower effective atomic number has been achieved.","PeriodicalId":46807,"journal":{"name":"IEEE Transactions on Radiation and Plasma Medical Sciences","volume":"9 3","pages":"296-303"},"PeriodicalIF":4.6,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10740386","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143553121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-03DOI: 10.1109/TRPMS.2024.3471251
A. Shultzman;R. Schütz;Y. Kurman;N. Lahav;G. Dosovitskiy;C. Roques-Carmes;Y. Bekenstein;G. Konstantinou;R. Latella;L. Zhang;F. Loignon-Houle;A. J. Gonzalez;J. M. Benlloch;I. Kaminer;P. Lecoq
This study focuses on advancing metascintillators to break the 100 ps barrier and approach the 10 ps target. We exploitnanophotonic features, specifically the Purcell effect, to shape and enhance the scintillation properties of the first-generation metascintillator. We demonstrate that a faster emission is achievable along with a more efficient conversionefficiency. This results in a coincidence time resolution improved by a factor of 1.3, crucial for TOF-PET applications.
{"title":"Toward a Second Generation of Metascintillators Using the Purcell Effect","authors":"A. Shultzman;R. Schütz;Y. Kurman;N. Lahav;G. Dosovitskiy;C. Roques-Carmes;Y. Bekenstein;G. Konstantinou;R. Latella;L. Zhang;F. Loignon-Houle;A. J. Gonzalez;J. M. Benlloch;I. Kaminer;P. Lecoq","doi":"10.1109/TRPMS.2024.3471251","DOIUrl":"https://doi.org/10.1109/TRPMS.2024.3471251","url":null,"abstract":"This study focuses on advancing metascintillators to break the 100 ps barrier and approach the 10 ps target. We exploitnanophotonic features, specifically the Purcell effect, to shape and enhance the scintillation properties of the first-generation metascintillator. We demonstrate that a faster emission is achievable along with a more efficient conversionefficiency. This results in a coincidence time resolution improved by a factor of 1.3, crucial for TOF-PET applications.","PeriodicalId":46807,"journal":{"name":"IEEE Transactions on Radiation and Plasma Medical Sciences","volume":"9 2","pages":"141-147"},"PeriodicalIF":4.6,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10704688","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143106284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Achieving a lower radiation dose and a faster imaging speed is a pivotal objective of computed tomography (CT) reconstruction. However, these often come at the cost of compromised reconstruction quality. With the advent of deep learning, numerous CT reconstruction methods rooted in this field have significantly improved the reconstruction performance. Recently, diffusion models have further enhanced training stability and imaging quality for CT. However, many of these methods only focus on CT image domain features, ignoring the intrinsic physical information of the imaging process. Although compressive sensing-based iterative reconstruction algorithms utilize physical prior information, their intricate iterative process poses challenges in training, subsequently influencing their efficiency. Motivated by these observations, we introduce a novel physics-regularized generalized diffusion model for CT reconstruction (PrideDiff). On the one hand, our method further improves the quality of reconstructed images by fusing physics-regularized iterative reconstruction methods with diffusion models. On the other hand, we propose a prior extraction module embedded with temporal features, which effectively improves the performance of the iteration process. Extensive experimental results demonstrate that PrideDiff outperforms several state-of-the-art methods in low-dose and sparse-view CT reconstruction tasks on different datasets, with faster reconstruction speed. We further discuss the effectiveness of relevant components in PrideDiff and validate the stability of the iterative reconstruction process, followed by detailed analysis of computational cost and inference time.
{"title":"PrideDiff: Physics-Regularized Generalized Diffusion Model for CT Reconstruction","authors":"Zexin Lu;Qi Gao;Tao Wang;Ziyuan Yang;Zhiwen Wang;Hui Yu;Hu Chen;Jiliu Zhou;Hongming Shan;Yi Zhang","doi":"10.1109/TRPMS.2024.3471677","DOIUrl":"https://doi.org/10.1109/TRPMS.2024.3471677","url":null,"abstract":"Achieving a lower radiation dose and a faster imaging speed is a pivotal objective of computed tomography (CT) reconstruction. However, these often come at the cost of compromised reconstruction quality. With the advent of deep learning, numerous CT reconstruction methods rooted in this field have significantly improved the reconstruction performance. Recently, diffusion models have further enhanced training stability and imaging quality for CT. However, many of these methods only focus on CT image domain features, ignoring the intrinsic physical information of the imaging process. Although compressive sensing-based iterative reconstruction algorithms utilize physical prior information, their intricate iterative process poses challenges in training, subsequently influencing their efficiency. Motivated by these observations, we introduce a novel physics-regularized generalized diffusion model for CT reconstruction (PrideDiff). On the one hand, our method further improves the quality of reconstructed images by fusing physics-regularized iterative reconstruction methods with diffusion models. On the other hand, we propose a prior extraction module embedded with temporal features, which effectively improves the performance of the iteration process. Extensive experimental results demonstrate that PrideDiff outperforms several state-of-the-art methods in low-dose and sparse-view CT reconstruction tasks on different datasets, with faster reconstruction speed. We further discuss the effectiveness of relevant components in PrideDiff and validate the stability of the iterative reconstruction process, followed by detailed analysis of computational cost and inference time.","PeriodicalId":46807,"journal":{"name":"IEEE Transactions on Radiation and Plasma Medical Sciences","volume":"9 2","pages":"157-168"},"PeriodicalIF":4.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10701005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143106286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1109/TRPMS.2024.3470836
Hideaki Tashima;Taiga Yamaya
Three-gamma imaging is attracting attention as a futuristic diagnostic imaging method that surpasses positron emission tomography (PET). Its conceptual key is using $beta ^{+}$ - $gamma $ nuclides that simultaneously emit a prompt gamma ray with the positron decay. In this review, we have categorized the utilizations of prompt gamma rays into three categories: 1) multiple positron emitter imaging; 2) reconstruction-less positron emission imaging; and 3) positronium lifetime imaging. Multiple positron emitter imaging utilizes the prompt gamma ray as a trigger to discriminate from signals of pure positron emitters to enable simultaneous injection and imaging of two different radioisotopes. Reconstruction-less positron emission imaging combines PET and Compton imaging technologies to estimate the source position as almost a point for each triple coincidence event. Positronium lifetime imaging utilizes the prompt gamma ray as a starting signal to measure the time difference between positronium formation and annihilation for each triple coincidence event as its lifetime. This is because the positronium lifetime is affected by the surrounding microenvironment of electrons, it is expected to provide new information regarding biological conditions, such as the hypoxia state. In this review we introduce the principles of the three categories of three-gamma imaging methods, prototype development, and demonstration experiments.
{"title":"Three-Gamma Imaging in Nuclear Medicine: A Review","authors":"Hideaki Tashima;Taiga Yamaya","doi":"10.1109/TRPMS.2024.3470836","DOIUrl":"https://doi.org/10.1109/TRPMS.2024.3470836","url":null,"abstract":"Three-gamma imaging is attracting attention as a futuristic diagnostic imaging method that surpasses positron emission tomography (PET). Its conceptual key is using \u0000<inline-formula> <tex-math>$beta ^{+}$ </tex-math></inline-formula>\u0000-\u0000<inline-formula> <tex-math>$gamma $ </tex-math></inline-formula>\u0000 nuclides that simultaneously emit a prompt gamma ray with the positron decay. In this review, we have categorized the utilizations of prompt gamma rays into three categories: 1) multiple positron emitter imaging; 2) reconstruction-less positron emission imaging; and 3) positronium lifetime imaging. Multiple positron emitter imaging utilizes the prompt gamma ray as a trigger to discriminate from signals of pure positron emitters to enable simultaneous injection and imaging of two different radioisotopes. Reconstruction-less positron emission imaging combines PET and Compton imaging technologies to estimate the source position as almost a point for each triple coincidence event. Positronium lifetime imaging utilizes the prompt gamma ray as a starting signal to measure the time difference between positronium formation and annihilation for each triple coincidence event as its lifetime. This is because the positronium lifetime is affected by the surrounding microenvironment of electrons, it is expected to provide new information regarding biological conditions, such as the hypoxia state. In this review we introduce the principles of the three categories of three-gamma imaging methods, prototype development, and demonstration experiments.","PeriodicalId":46807,"journal":{"name":"IEEE Transactions on Radiation and Plasma Medical Sciences","volume":"8 8","pages":"853-866"},"PeriodicalIF":4.6,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10700810","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142587582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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