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He W, Zhao Y, Zeng H, Huang W, Yang H, Zhao X, Wang Q, Wang L, Niu M, Zhang L, Ren Q, Gu Z. Design and characterization of a hybrid PET detector with DOI capability. Med Phys 2024. [PMID: 39032050 DOI: 10.1002/mp.17313] [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: 10/16/2023] [Revised: 06/07/2024] [Accepted: 07/02/2024] [Indexed: 07/22/2024] Open
Abstract
BACKGROUND Monolithic or semi-monolithic detectors are attractive for positron emission tomography (PET) scanners with depth-of-interaction (DOI) capability. However, they often require complicated calibrations to determine the interaction positions of gamma photons. PURPOSE We introduce a novel hybrid detector design that combines pixelated and semi-monolithic elements to achieve DOI capability while simplifying the calibrations for positioning. METHODS A prototype detector with eight hybrid lutetium-yttrium oxyorthosilicate (LYSO) layers having dimensions of 25.8 × 12.9 × 15 mm3 was constructed. The energy-weighted and energy-squared weighted averages were used for estimating the x- (pixelated direction) and y-positions (non-pixelated direction). Pseudo-pixels were defined as discrete areas on the flood image based on the crystal look-up table (LUT). The intrinsic spatial resolutions in the pixelated and non-pixelated directions were measured. The ratio of the maximum to the sum of the multipixel photon counter (MPPC) signals was used to estimate the DOI positions. The coincidence timing resolution (CTR) was measured using the average and energy-weighted average of the earliest n time stamps. Two energy windows of 250-700 and 400-600 keV were applied for the measurements. RESULTS The pattern of the flood images showed discrete event clusters, demonstrating that simple calibrations for determining the x- and y-positions of events could be achieved. Under 400-600 keV energy window, the average intrinsic spatial resolutions were 1.15 and 1.34 mm for the pixelated and non-pixelated directions; the average DOI resolution of the second row of pseudo-pixels was 5.1 mm in full width at half maximum (FWHM); when using the energy-weighted average of the earliest four-time stamps, the best CTR of 350 ps was achieved. Applying a broader energy window of 250-700 keV only slightly degrades the DOI resolution while maintaining the intrinsic resolution; the best CTR degrades to 410 ps. CONCLUSIONS The proposed hybrid detector concept was verified, and a prototype detector showed high performance for 3D positioning and timing resolution. The novel detector concept shows promise for preclinical and clinical PET scanners with DOI capability.
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Affiliation(s)
- Wen He
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China
- Peking University Shenzhen Graduate School, Shenzhen, China
| | - Yangyang Zhao
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China
| | - Honghao Zeng
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China
- Ciechanover Institute of Precision and Regenerative Medicine, School of Medicine, The Chinese University of Hong Kong, Shenzhen, China
| | - Wenjie Huang
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China
| | - Hang Yang
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China
| | - Xin Zhao
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China
| | - Qiang Wang
- 26th Institute of China Electronics Technology Group Corporation, Chongqing, China
| | - Lu Wang
- 26th Institute of China Electronics Technology Group Corporation, Chongqing, China
| | - Ming Niu
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China
| | - Lei Zhang
- Peking University Shenzhen Graduate School, Shenzhen, China
- Institute of Cancer Research, Shenzhen Bay Laboratory, Shenzhen, China
| | - Qiushi Ren
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China
- Peking University Shenzhen Graduate School, Shenzhen, China
| | - Zheng Gu
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, China
- Peking University Shenzhen Graduate School, Shenzhen, China
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Nguyen HTM, Das N, Ricks M, Zhong X, Takematsu E, Wang Y, Ruvalcaba C, Mehadji B, Roncali E, Chan CKF, Pratx G. Ultrasensitive and multiplexed tracking of single cells using whole-body PET/CT. SCIENCE ADVANCES 2024; 10:eadk5747. [PMID: 38875333 PMCID: PMC11177933 DOI: 10.1126/sciadv.adk5747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 05/13/2024] [Indexed: 06/16/2024]
Abstract
In vivo molecular imaging tools are crucially important for elucidating how cells move through complex biological systems; however, achieving single-cell sensitivity over the entire body remains challenging. Here, we report a highly sensitive and multiplexed approach for tracking upward of 20 single cells simultaneously in the same subject using positron emission tomography (PET). The method relies on a statistical tracking algorithm (PEPT-EM) to achieve a sensitivity of 4 becquerel per cell and a streamlined workflow to reliably label single cells with over 50 becquerel per cell of 18F-fluorodeoxyglucose (FDG). To demonstrate the potential of the method, we tracked the fate of more than 70 melanoma cells after intracardiac injection and found they primarily arrested in the small capillaries of the pulmonary, musculoskeletal, and digestive organ systems. This study bolsters the evolving potential of PET in offering unmatched insights into the earliest phases of cell trafficking in physiological and pathological processes and in cell-based therapies.
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Affiliation(s)
- Hieu T. M. Nguyen
- School of Medicine, Department of Radiation Oncology and Medical Physics, Stanford University, Stanford, CA 94305, USA
| | - Neeladrisingha Das
- School of Medicine, Department of Radiation Oncology and Medical Physics, Stanford University, Stanford, CA 94305, USA
| | - Matthew Ricks
- School of Medicine, Department of Radiological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Xiaoxu Zhong
- School of Medicine, Department of Radiation Oncology and Medical Physics, Stanford University, Stanford, CA 94305, USA
| | - Eri Takematsu
- School of Medicine, Department of Surgery, Stanford University, Stanford, CA 94305, USA
| | - Yuting Wang
- School of Medicine, Department of Surgery, Stanford University, Stanford, CA 94305, USA
| | - Carlos Ruvalcaba
- Department of Biomedical Engineering, University of California, Davis, Davis, CA 95616, USA
| | - Brahim Mehadji
- Department of Radiology, University of California, Davis, Davis, CA 95616, USA
| | - Emilie Roncali
- Department of Biomedical Engineering, University of California, Davis, Davis, CA 95616, USA
- Department of Radiology, University of California, Davis, Davis, CA 95616, USA
| | - Charles K. F. Chan
- School of Medicine, Department of Surgery, Stanford University, Stanford, CA 94305, USA
| | - Guillem Pratx
- School of Medicine, Department of Radiation Oncology and Medical Physics, Stanford University, Stanford, CA 94305, USA
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Zeng X, Zhang Z, Li D, Huang X, Wang Z, Wang Y, Zhou W, Wang P, Zhu M, Wei Q, Gong H, Wei L. Evaluation of monolithic crystal detector with dual-ended readout utilizing multiplexing method. Phys Med Biol 2024; 69:085003. [PMID: 38484392 DOI: 10.1088/1361-6560/ad3417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 03/14/2024] [Indexed: 04/04/2024]
Abstract
Objective.Monolithic crystal detectors are increasingly being applied in positron emission tomography (PET) devices owing to their excellent depth-of-interaction (DOI) resolution capabilities and high detection efficiency. In this study, we constructed and evaluated a dual-ended readout monolithic crystal detector based on a multiplexing method.Approach.We employed two 12 × 12 silicon photomultiplier (SiPM) arrays for readout, and the signals from the 12 × 12 array were merged into 12 X and 12 Y channels using channel multiplexing. In 2D reconstruction, three methods based on the centre of gravity (COG) were compared, and the concept of thresholds was introduced. Furthermore, a light convolutional neural network (CNN) was employed for testing. To enhance depth localization resolution, we proposed a method by utilizing the mutual information from both ends of the SiPMs. The source width and collimation effect were simulated using GEANT4, and the intrinsic spatial resolution was separated from the measured values.Main results.At an operational voltage of 29 V for the SiPM, an energy resolution of approximately 12.5 % was achieved. By subtracting a 0.8 % threshold from the total energy in every channel, a 2D spatial resolution of approximately 0.90 mm full width at half maximum (FWHM) can be obtained. Furthermore, a higher level of resolution, approximately 0.80 mm FWHM, was achieved using a CNN, with some alleviation of edge effects. With the proposed DOI method, a significant 1.36 mm FWHM average DOI resolution can be achieved. Additionally, it was found that polishing and black coating on the crystal surface yielded smaller edge effects compared to a rough surface with a black coating.Significance.The introduction of a threshold in COG method and a dual-ended readout scheme can lead to excellent spatial resolution for monolithic crystal detectors, which can help to develop PET systems with both high sensitivity and high spatial resolution.
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Affiliation(s)
- Xiangtao Zeng
- Beijing Engineering Research Centre of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Jinan Laboratory of Applied Nuclear Science, Jinan 250131, People's Republic of China
- CAEA Centre of Excellence on Nuclear Technology Applications for Nuclear Detection and Imaging, Beijing 100049, People's Republic of China
| | - Zhiming Zhang
- Beijing Engineering Research Centre of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Jinan Laboratory of Applied Nuclear Science, Jinan 250131, People's Republic of China
- CAEA Centre of Excellence on Nuclear Technology Applications for Nuclear Detection and Imaging, Beijing 100049, People's Republic of China
| | - Daowu Li
- Beijing Engineering Research Centre of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Jinan Laboratory of Applied Nuclear Science, Jinan 250131, People's Republic of China
- CAEA Centre of Excellence on Nuclear Technology Applications for Nuclear Detection and Imaging, Beijing 100049, People's Republic of China
| | - Xianchao Huang
- Beijing Engineering Research Centre of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Jinan Laboratory of Applied Nuclear Science, Jinan 250131, People's Republic of China
- CAEA Centre of Excellence on Nuclear Technology Applications for Nuclear Detection and Imaging, Beijing 100049, People's Republic of China
| | - Zhuoran Wang
- Beijing Engineering Research Centre of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Jinan Laboratory of Applied Nuclear Science, Jinan 250131, People's Republic of China
- CAEA Centre of Excellence on Nuclear Technology Applications for Nuclear Detection and Imaging, Beijing 100049, People's Republic of China
| | - Yingjie Wang
- Beijing Engineering Research Centre of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Jinan Laboratory of Applied Nuclear Science, Jinan 250131, People's Republic of China
- CAEA Centre of Excellence on Nuclear Technology Applications for Nuclear Detection and Imaging, Beijing 100049, People's Republic of China
| | - Wei Zhou
- Beijing Engineering Research Centre of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Jinan Laboratory of Applied Nuclear Science, Jinan 250131, People's Republic of China
- CAEA Centre of Excellence on Nuclear Technology Applications for Nuclear Detection and Imaging, Beijing 100049, People's Republic of China
| | - Peilin Wang
- Beijing Engineering Research Centre of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Jinan Laboratory of Applied Nuclear Science, Jinan 250131, People's Republic of China
- CAEA Centre of Excellence on Nuclear Technology Applications for Nuclear Detection and Imaging, Beijing 100049, People's Republic of China
| | - Meiling Zhu
- Beijing Engineering Research Centre of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Jinan Laboratory of Applied Nuclear Science, Jinan 250131, People's Republic of China
- CAEA Centre of Excellence on Nuclear Technology Applications for Nuclear Detection and Imaging, Beijing 100049, People's Republic of China
| | - Qing Wei
- Beijing Engineering Research Centre of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Jinan Laboratory of Applied Nuclear Science, Jinan 250131, People's Republic of China
- CAEA Centre of Excellence on Nuclear Technology Applications for Nuclear Detection and Imaging, Beijing 100049, People's Republic of China
| | - Huixing Gong
- Beijing Engineering Research Centre of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Jinan Laboratory of Applied Nuclear Science, Jinan 250131, People's Republic of China
- CAEA Centre of Excellence on Nuclear Technology Applications for Nuclear Detection and Imaging, Beijing 100049, People's Republic of China
| | - Long Wei
- Beijing Engineering Research Centre of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Jinan Laboratory of Applied Nuclear Science, Jinan 250131, People's Republic of China
- CAEA Centre of Excellence on Nuclear Technology Applications for Nuclear Detection and Imaging, Beijing 100049, People's Republic of China
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He W, Zhao Y, Huang W, Zhao X, Niu M, Yang H, Zhang L, Ren Q, Gu Z. A multi-resolution TOF-DOI detector for human brain dedicated PET scanner. Phys Med Biol 2024; 69:025023. [PMID: 38181423 DOI: 10.1088/1361-6560/ad1b6b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 01/05/2024] [Indexed: 01/07/2024]
Abstract
Objective. We propose a single-ended readout, multi-resolution detector design that can achieve high spatial, depth-of-interaction (DOI), and time-of-flight (TOF) resolutions, as well as high sensitivity for human brain-dedicated positron emission tomography (PET) scanners.Approach. The detector comprised two layers of LYSO crystal arrays and a lightguide in between. The top (gamma ray entrance) layer consisted of a 16 × 16 array of 1.53 × 1.53 × 6 mm3LYSO crystals for providing high spatial resolution. The bottom layer consisted of an 8 × 8 array of 3.0 × 3.0 × 15 mm3LYSO crystals that were one-to-one coupled to an 8 × 8 multipixel photon counter (MPPC) array for providing high TOF resolution. The 2 mm thick lightguide introduces inter-crystal light sharing that causes variations of the light distribution patterns for high DOI resolution. The detector was read out by a PETsys TOFPET2 application-specific integrated circuit.Main result. The top and bottom layers were distinguished by a convolutional neural network with 97% accuracy. All crystals in the top and bottom layers were resolved. The inter-crystal scatter (ICS) events in the bottom layer were identified, and the measured average DOI resolution of the bottom layer was 4.1 mm. The coincidence time resolution (CTR) for the top-top, top-bottom, and bottom-bottom coincidences was 476 ps, 405 ps, and 298 ps, respectively. When ICS events were excluded from the bottom layer, the CTR of the bottom-bottom coincidence was 277 ps.Significance. The top layer of the proposed two-layer detector achieved a high spatial resolution and the bottom layer achieved a high TOF resolution. Together with its high DOI resolution and detection efficiency, the proposed detector is well suited for next-generation high-performance brain-dedicated PET scanners.
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Affiliation(s)
- Wen He
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
- Peking University Shenzhen Graduate School, Shenzhen, People's Republic of China
| | - Yangyang Zhao
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
| | - Wenjie Huang
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
| | - Xin Zhao
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
| | - Ming Niu
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
| | - Hang Yang
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
| | - Lei Zhang
- Peking University Shenzhen Graduate School, Shenzhen, People's Republic of China
- Institute of Cancer Research, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
| | - Qiushi Ren
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
- Peking University Shenzhen Graduate School, Shenzhen, People's Republic of China
| | - Zheng Gu
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, People's Republic of China
- Peking University Shenzhen Graduate School, Shenzhen, People's Republic of China
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Kuang Z, Zhang L, Ren N, Kinyanjui SM, Liu Z, Sun T, Hu Z, Yang Y. Effect of depth of interaction resolution on the spatial resolution of SIAT aPET. Phys Med Biol 2023; 68:22NT02. [PMID: 37890466 DOI: 10.1088/1361-6560/ad078b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Accepted: 10/27/2023] [Indexed: 10/29/2023]
Abstract
Objective.Spatial resolution is a crucial parameter for a positron emission tomography (PET) scanner. The spatial resolution of a high-resolution small animal PET scanner is significantly influenced by the effect of depth of interaction (DOI) uncertainty. The aim of this work is to investigate the impact of DOI resolution on the spatial resolution of a small animal PET scanner called SIAT aPET and determine the required DOI resolution to achieve nearly uniform spatial resolution within the field of view (FOV).Approach. The SIAT aPET detectors utilize 1.0 × 1.0 × 20 mm3crystals, with an average DOI resolution of ∼2 mm. A default number of 16 DOI bins are used during data acquisition. First, a Na-22 point source was scanned in the center of the axial FOV with different radial offsets. Then, a Derenzo phantom was scanned at radial offsets of 0 and 15 mm in the center axial FOV. The measured DOI information was rebinned to 1, 2, 4 and 8 DOI bins to mimic different DOI resolutions of the detectors during image reconstruction.Main results. Significant artifacts were observed in images obtained from both the point source and Derenzo phantom when using only one DOI bin. When accurate measurement of DOI is not achieved, degradation in spatial resolution is more pronounced in the radial direction compared to tangential and axial directions for large radial offsets. The radial spatial resolutions at a 30 mm radial offset are 5.05, 2.62, 1.24, 0.86 and 0.78 mm when using 1, 2, 4, 8, or 16 DOI bins, respectively. The axial spatial resolution improved from ∼1.3 to 0.7 mm as the number of DOI bins increased from 1 to 16 at radial offsets from 0 to 25 mm. Two DOI bins are required to obtain images without significant artifacts. The required DOI resolution is about three times the crystal width of SIAT aPET to achieve a uniform submillimeter spatial resolution within the central 60 mm FOV and resolve the 1 mm rods of the Derenzo phantom at both positions.
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Affiliation(s)
- Zhonghua Kuang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
- School of Physics and Electronics-Electrical Engineering, Xiangnan University, Chenzhou 423000, People's Republic of China
| | - Ling Zhang
- School of Medicine, Hunan University of Medicine, Huaihua 418000, People's Republic of China
| | - Ning Ren
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Samuel M Kinyanjui
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Zheng Liu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Tao Sun
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Zhanli Hu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Yongfeng Yang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
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Nguyen HT, Das N, Wang Y, Ruvalcaba C, Mehadji B, Roncali E, Chan CK, Pratx G. Efficient and multiplexed tracking of single cells using whole-body PET/CT. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.23.554536. [PMID: 37662335 PMCID: PMC10473747 DOI: 10.1101/2023.08.23.554536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
In vivo molecular imaging tools are crucially important for elucidating how cells move through complex biological systems, however, achieving single-cell sensitivity over the entire body remains challenging. Here, we report a highly sensitive and multiplexed approach for tracking upwards of 20 single cells simultaneously in the same subject using positron emission tomography (PET). The method relies on a new tracking algorithm (PEPT-EM) to push the cellular detection threshold to below 4 Bq/cell, and a streamlined workflow to reliably label single cells with over 50 Bq/cell of 18F-fluorodeoxyglucose (FDG). To demonstrate the potential of method, we tracked the fate of over 70 melanoma cells after intracardiac injection and found they primarily arrested in the small capillaries of the pulmonary, musculoskeletal, and digestive organ systems. This study bolsters the evolving potential of PET in offering unmatched insights into the earliest phases of cell trafficking in physiological and pathological processes and in cell-based therapies.
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Affiliation(s)
- Hieu T.M. Nguyen
- Stanford University, School of Medicine, Department of Radiation Oncology and Medical Physics
| | - Neeladrisingha Das
- Stanford University, School of Medicine, Department of Radiation Oncology and Medical Physics
| | - Yuting Wang
- Stanford University, School of Medicine, Department of Surgery
| | - Carlos Ruvalcaba
- University of California, Davis, Department of Biomedical Engineering
| | - Brahim Mehadji
- University of California, Davis, Department of Radiology
| | - Emilie Roncali
- University of California, Davis, Department of Biomedical Engineering
- University of California, Davis, Department of Radiology
| | | | - Guillem Pratx
- Stanford University, School of Medicine, Department of Radiation Oncology and Medical Physics
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Liu Z, Mungai S, Niu M, Kuang Z, Ren N, Wang X, Sang Z, Yang Y. Edge effect reduction of high-resolution PET detectors using LYSO and GAGG phoswich crystals. Phys Med Biol 2023; 68. [PMID: 36808920 DOI: 10.1088/1361-6560/acbde1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 02/21/2023] [Indexed: 02/23/2023]
Abstract
Objective. Small-animal positron emission tomography (PET) is a powerful preclinical imaging tool in animal model studies. The spatial resolution and sensitivity of current PET scanners developed for small-animal imaging need to be improved to increase the quantitative accuracy of preclinical animal studies. This study aimed to improve the identification capability of edge scintillator crystals of a PET detector which will enable to apply a crystal array with the same cross-section area as the active area of a photodetector for improving the detection area and thus reducing or eliminating the inter-detector gaps.Approach. PET detectors using crystal arrays with mixed lutetium yttrium orthosilicate (LYSO) and gadolinium aluminum gallium garnet (GAGG) crystals were developed and evaluated. The crystal arrays consisted of 31 × 31 array of 0.49 × 0.49 × 20 mm3crystals; they were read out by two silicon photomultiplier arrays with pixel sizes of 2 × 2 mm2that were placed at both ends of the crystal arrays. The second or first outermost layer of the LYSO crystals was replaced by GAGG crystals in the two crystal arrays. The two crystal types were identified using a pulse-shape discrimination technique to provide better edge crystal identification.Main results. Using the pulse shape discrimination technique, almost all (except for a few edge) crystals were resolved in the two detectors; high sensitivity was achieved by using the scintillator array and the photodetector with the same areas and achieved high resolution by using crystals with sizes equal to 0.49 × 0.49 × 20 mm3. Energy resolutions of 19.3 ± 1.8% and 18.9 ± 1.5%, depth-of-interaction resolutions of 2.02 ± 0.17 mm and 2.04 ± 0.18 mm, and timing resolutions of 1.6 ± 0.2 ns and 1.5 ± 0.2 ns were achieved by the two detectors, respectively.Significance. In summary, novel three-dimensional high-resolution PET detectors consisting of a mixture of LYSO and GAGG crystals were developed. The detectors significantly improve the detection area with the same photodetectors and thus improve the detection efficiency.
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Affiliation(s)
- Zheng Liu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Samuel Mungai
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Ming Niu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Zhonghua Kuang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Ning Ren
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Xiaohui Wang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Ziru Sang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Yongfeng Yang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
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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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Microliter-scale reaction arrays for economical high-throughput experimentation in radiochemistry. Sci Rep 2022; 12:10263. [PMID: 35715457 PMCID: PMC9205965 DOI: 10.1038/s41598-022-14022-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 05/31/2022] [Indexed: 01/14/2023] Open
Abstract
The increasing number of positron-emission tomography (PET) tracers being developed to aid drug development and create new diagnostics has led to an increased need for radiosynthesis development and optimization. Current radiosynthesis instruments are designed to produce large-scale clinical batches and are often limited to performing a single synthesis before they must be decontaminated by waiting for radionuclide decay, followed by thorough cleaning or disposal of synthesizer components. Though with some radiosynthesizers it is possible to perform a few sequential radiosyntheses in a day, none allow for parallel radiosyntheses. Throughput of one or a few experiments per day is not well suited for rapid optimization experiments. To combat these limitations, we leverage the advantages of droplet-radiochemistry to create a new platform for high-throughput experimentation in radiochemistry. This system contains an array of 4 heaters, each used to heat a set of 16 reactions on a small chip, enabling 64 parallel reactions for the rapid optimization of conditions in any stage of a multi-step radiosynthesis process. As examples, we study the syntheses of several 18F-labeled radiopharmaceuticals ([18F]Flumazenil, [18F]PBR06, [18F]Fallypride, and [18F]FEPPA), performing > 800 experiments to explore the influence of parameters including base type, base amount, precursor amount, solvent, reaction temperature, and reaction time. The experiments were carried out within only 15 experiment days, and the small volume (~ 10 μL compared to the ~ 1 mL scale of conventional instruments) consumed ~ 100 × less precursor per datapoint. This new method paves the way for more comprehensive optimization studies in radiochemistry and substantially shortening PET tracer development timelines.
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Liu Z, Niu M, Kuang Z, Ren N, Wu S, Cong L, Wang X, Sang Z, Williams C, Yang Y. High resolution detectors for whole-body PET scanners by using dual-ended readout. EJNMMI Phys 2022; 9:29. [PMID: 35445890 PMCID: PMC9023628 DOI: 10.1186/s40658-022-00460-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 04/08/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Most current whole-body positron emission tomography (PET) scanners use detectors with high timing resolution to measure the time-of-flight of two 511 keV photons, improving the signal-to-noise ratio of PET images. However, almost all current whole-body PET scanners use detectors without depth-encoding capability; therefore, their spatial resolution can be affected by the parallax effect. METHODS In this work, four depth-encoding detectors consisting of LYSO arrays with crystals of 2.98 × 2.98 × 20 mm3, 2.98 × 2.98 × 30 mm3, 1.95 × 1.95 × 20 mm3, and 1.95 × 1.95 × 30 mm3, respectively, were read at both ends, with 6 × 6 mm2 silicon photomultiplier (SiPM) pixels in a 4 × 4 array being used. The timing signals of the detectors were processed individually using an ultrafast NINO application-specific integrated circuit (ASIC) to obtain good timing resolution. The 16 energy signals of the SiPM array were read using a row and column summing circuit to obtain four position-encoding energy signals. RESULTS The four PET detectors provided good flood histograms in which all crystals could be clearly resolved, the crystal energy resolutions measured being 10.2, 12.1, 11.4 and 11.7% full width at half maximum (FWHM), at an average crystal depth of interaction (DOI) resolution of 3.5, 3.9, 2.7, and 3.0 mm, respectively. The depth dependence of the timing of each SiPM was measured and corrected, the timing of the two SiPMs being used as the timing of the dual-ended readout detector. The four detectors provided coincidence time resolutions of 180, 214, 239, and 263 ps, respectively. CONCLUSIONS The timing resolution of the dual-ended readout PET detector was approximately 20% better than that of the single-ended readout detector using the same LYSO array, SiPM array, and readout electronics. The detectors developed in this work used long crystals with small cross-sections and provided good flood histograms, DOI, energy, and timing resolutions, suggesting that they could be used to develop whole-body PET scanners with high sensitivity, uniform high spatial resolution, and high timing resolution.
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Affiliation(s)
- Zheng Liu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Ming Niu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Zhonghua Kuang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Ning Ren
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - San Wu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Longhan Cong
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Xiaohui Wang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Ziru Sang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Crispin Williams
- European Centre for Nuclear Research (CERN), Geneva, Switzerland
| | - Yongfeng Yang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
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Niu M, Liu Z, Kuang Z, Wang X, Ren N, Sang Z, Wu S, Cong L, Sun T, Hu Z, Yang Y. Ultra-high resolution depth-encoding small animal PET detectors: Using GAGG and LYSO crystal arrays. Med Phys 2022; 49:3006-3020. [PMID: 35301730 DOI: 10.1002/mp.15606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 03/03/2022] [Accepted: 03/03/2022] [Indexed: 11/12/2022] Open
Abstract
PURPOSE Small animal PET scanners are widely used in current biomedical research. The study aimed to develop high efficiency and ultra-high resolution detectors that could be used to develop a small animal PET scanner with high sensitivity and spatial resolution approaching to its physical limit. METHODS 4 crystal arrays were fabricated and measured in this study. Crystal arrays 1 and 2 consisted of 38 × 38 GAGG and LYSO crystals of 0.4 × 0.4 × 20 mm3 size. Crystal array 3 consisted of 16 × 16 GAGG crystals of 0.3 × 0.3 × 20 mm3 size, and crystal array 4 consisted of 24 × 24 LYSO crystals 0.3 × 0.3 × 20 mm3 in size. The crystal arrays were dual-ended readouts using 8 × 8 SiPM arrays of 2 × 2 mm2 pixel area. The SiPM array was read-out using a signal multiplexing circuit to convert the 64 output signals into 4 position-encoding signals. The performances of the 4 detectors in terms of flood histogram, energy resolution, depth of interaction resolution and timing resolution were measured. RESULTS The GAGG detectors provided better flood histograms, ∼30% higher photopeak amplitude, ∼20% higher energy resolution, ∼12% worse DOI resolution and ∼15% worse timing resolution compared with LYSO detectors of the same crystal size. These 4 detectors provided DOI resolutions of <2 mm, energy resolutions of <22% and timing resolutions of <1.6 ns. All crystals of 0.4 × 0.4 × 20 mm3 and 0.3 × 0.3 × 20 mm3 could be clearly resolved if the crystal array was 1 mm smaller in the four sides than that in the SiPM array. CONCLUSIONS High DOI resolution PET detectors were developed using both GAGG and LYSO arrays with crystal sizes of 0.3 and 0.4 mm, respectively, and a length of 20 mm. The detectors can be used in the future to develop small animal PET scanners, especially dedicated mouse imaging PET scanners, which can simultaneously achieve high sensitivity and ultra-high spatial resolution. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Ming Niu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Zheng Liu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Zhonghua Kuang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Xiaohui Wang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Ning Ren
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Ziru Sang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - San Wu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Longhan Cong
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Tao Sun
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Zhanli Hu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Yongfeng Yang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
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Kang HG, Tashima H, Nishikido F, Akamatsu G, Wakizaka H, Higuchi M, Yamaya T. Initial results of a mouse brain PET insert with a staggered 3-layer DOI detector. Phys Med Biol 2021; 66. [PMID: 34666328 DOI: 10.1088/1361-6560/ac311c] [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: 08/26/2021] [Accepted: 10/19/2021] [Indexed: 11/11/2022]
Abstract
Objective.Small animal positron emission tomography (PET) requires a submillimeter resolution for better quantification of radiopharmaceuticals. On the other hand, depth-of-interaction (DOI) information is essential to preserve the spatial resolution while maintaining the sensitivity. Recently, we developed a staggered 3-layer DOI detector with 1 mm crystal pitch and 15 mm total crystal thickness, but we did not demonstrate the imaging performance of the DOI detector with full ring geometry. In this study we present initial imaging results obtained for a mouse brain PET prototype developed with the staggered 3-layer DOI detector.Approach.The prototype had 53 mm inner diameter and 11 mm axial field-of-view. The PET scanner consisted of 16 DOI detectors each of which had a staggered 3-layer LYSO crystal array (4/4/7 mm) coupled to a 4 × 4 silicon photomultiplier array. The physical performance was evaluated in terms of the NEMA NU 4 2008 protocol.Main Results.The measured spatial resolutions at the center and 15 mm radial offset were 0.67 mm and 1.56 mm for filtered-back-projection, respectively. The peak absolute sensitivity of 0.74% was obtained with an energy window of 400-600 keV. The resolution phantom imaging results show the clear identification of a submillimetric rod pattern with the ordered-subset expectation maximization algorithm. The inter-crystal scatter rejection using a narrow energy window could enhance the resolvability of a 0.75 mm rod significantly.Significance.In an animal imaging experiment, the detailed mouse brain structures such as cortex and thalamus were clearly identified with high contrast. In conclusion, we successfully developed the mouse brain PET insert prototype with a staggered 3-layer DOI detector.
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Affiliation(s)
- Han Gyu Kang
- National Institutes for Quantum Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, Japan
| | - Hideaki Tashima
- National Institutes for Quantum Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, Japan
| | - Fumihiko Nishikido
- National Institutes for Quantum Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, Japan
| | - Go Akamatsu
- National Institutes for Quantum Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, Japan
| | - Hidekazu Wakizaka
- National Institutes for Quantum Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, Japan
| | - Makoto Higuchi
- National Institutes for Quantum Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, Japan
| | - Taiga Yamaya
- National Institutes for Quantum Science and Technology (QST), 4-9-1, Anagawa, Inage-ku, Chiba, Japan
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Cheng X, Hu K, Yang D, Shao Y. A compact and lightweight small animal PET with uniform high-resolution for onboard PET/CT image-guided preclinical radiation oncology research. Phys Med Biol 2021; 66. [PMID: 34592731 DOI: 10.1088/1361-6560/ac2bb4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/30/2021] [Indexed: 11/12/2022]
Abstract
OBJECTIVE In contrast to clinical radiation therapy (RT) that ubiquitously uses PET/CT image to accurately guide RT, all current commercial animal irradiators can only provide CT image-guided preclinical RT that severely limits their capability for preclinical and compatibility for translational radiation oncology research. To address this problem, we have developed a compact and lightweight PET with uniform, high spatial resolution that is suited to be installed inside an existing animal irradiator for potential onboard PET/CT image-guided preclinical RT research. APPROACH The design focused on the balance of achieving sufficient imaging performance for practical preclinical RT guidance with constrained size and weight. The detector head consists of a ring of 12 detector panels in a dodecagon configuration and 12 front-end electronics boards that are closely attached to the detector panels. The overall size and weight of the detector head are 33.0 cm diameter, 11.0 cm axial length and ∼6.5 kg weight that can be installed inside an existing irradiator. Each detector panel has a 30 × 30 array of 1 × 1 × 20 mm3LYSO scintillators with depth-of-interaction (DOI) measurement. The front-end electronics boards process and convert detected signals to digital signals and transfer them to system electronics and data acquisition located outside the irradiator through low-voltage-differential-signaling cables. MAIN RESULTS The typical energy, DOI and coincidence timing resolutions are around 22.1%, 3.1 mm, and 1.92 ns. The imaging field-of-view (FOV) is 8.0 cm diameter and 3.5 cm axial length. The performance evaluations show a 1.8% sensitivity at the center FOV, uniform ∼1.1 mm resolution within 6 cm diameter FOV, and all rods of 1.0 mm diameter can be clearly resolved from the image of an ultra-micro hot-rods phantom. SIGNIFICANCE Overall, this compact and lightweight PET has demonstrated its designed capability and performance sufficient for providing onboard functional/biological/molecular image to guide the preclinical RT research.
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Affiliation(s)
- Xinyi Cheng
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75057, United States of America
| | - Kun Hu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75057, United States of America
| | - Dongxu Yang
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75057, United States of America
| | - Yiping Shao
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75057, United States of America
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Zhang X, Yu H, Xie Q, Xie S, Ye B, Guo M, Zhao Z, Huang Q, Xu J, Peng Q. Design study of a PET detector with 0.5 mm crystal pitch for high-resolution preclinical imaging. Phys Med Biol 2021; 66. [PMID: 34130263 DOI: 10.1088/1361-6560/ac0b82] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 06/15/2021] [Indexed: 11/12/2022]
Abstract
Preclinical positron emission tomography (PET) is a sensitive and quantitative molecule imaging modality widely used in characterizing the biological processes and diseases in small animals. The purpose of this study is to investigate the methods to optimize a PET detector for high-resolution preclinical imaging. The PET detector proposed in this study consists of a 28 × 28 array of LYSO crystals 0.5 × 0.5 × 6.25 mm3in size, a wedged lightguide, and a 6 × 6 array of SiPMs 3 × 3 mm2in size. The simulation results showed that the most uniform flood map was achieved when the thickness of the lightguide was 2.35 mm. The quality of the flood map was significantly improved by suppressing the electronics noises using the simple threshold method with a best threshold. The peak-to-valley ratio of flood map improved 25.4% when the algorithm of ICS rejection was applied. An energy resolution (12.96% ± 1.03%) was measured on the prototype scanner constructed with 12 proposed detectors. Lastly, a prototype preclinic PET imager was constructed with 12 optimized detectors. The point source experiment was performed and an excellent spatial resolution (axial: 0.56 mm, tangential: 0.46 mm, radial: 0.42 mm) was achieved with the proposed high-performance PET detectors.
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Affiliation(s)
- Xi Zhang
- School of Mechanical Science and Engineering, Huazhong University of Science and Technology, 430074, Wuhan, People's Republic of China
| | - Hongsen Yu
- School of Mechanical Science and Engineering, Huazhong University of Science and Technology, 430074, Wuhan, People's Republic of China
| | - Qiangqiang Xie
- School of Mechanical Science and Engineering, Huazhong University of Science and Technology, 430074, Wuhan, People's Republic of China
| | - Siwei Xie
- Institute of Biomedical Engineering Shenzhen Bay Laboratory, Shenzhen, 518132, People's Republic of China
| | - Baihezi Ye
- School of Mechanical Science and Engineering, Huazhong University of Science and Technology, 430074, Wuhan, People's Republic of China
| | - Minghao Guo
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, People's Republic of China
| | - Zhixiang Zhao
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, People's Republic of China
| | - Qiu Huang
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, People's Republic of China
| | - Jianfeng Xu
- School of Mechanical Science and Engineering, Huazhong University of Science and Technology, 430074, Wuhan, People's Republic of China
| | - Qiyu Peng
- Institute of Biomedical Engineering Shenzhen Bay Laboratory, Shenzhen, 518132, People's Republic of China
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Zhang X, Ye B, Yu H, Zhang Y, Xie S, Xu J, Peng Q. Depth of Interaction Measurements Based on Rectangular Light Sharing Window Technology and Nine-Crystals-to-One-SiPM Coupling Method. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2021. [DOI: 10.1109/trpms.2020.3023073] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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16
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Kang HG, Nishikido F, Yamaya T. A staggered 3-layer DOI PET detector using BaSO4 reflector for enhanced crystal identification and inter-crystal scattering event discrimination capability. Biomed Phys Eng Express 2021; 7. [DOI: 10.1088/2057-1976/abf6a8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 04/09/2021] [Indexed: 01/22/2023]
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17
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Zhang C, Wang X, Sun M, Kuang Z, Zhang X, Ren N, Wu S, Sang Z, Sun T, Hu Z, Yang Y, Liu Z. A thick semi-monolithic scintillator detector for clinical PET scanners. Phys Med Biol 2021; 66:065023. [PMID: 33709958 DOI: 10.1088/1361-6560/abe761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Both monolithic and semi-monolithic scintillator positron emission tomography (PET) detectors can measure the depth of interaction with single-ended readout. Usually scintillators with a thickness of 10 mm or less are used since the position resolutions of the detectors degrade as the scintillator thickness increases. In this work, the performance of a 20 mm thick long rectangular semi-monolithic scintillator PET detector was measured by using both single-ended and dual-ended readouts with silicon photomultiplier (SiPM) arrays to provide a high detection efficiency. The semi-monolithic scintillator detector consists of nine lutetium-yttrium oxyorthosilicate slices measuring 1.37 × 51.2 × 20 mm3 with erythrocyte sedimentation rate foils of 0.065 mm thickness in between the slices. The SiPM array at each end of the scintillator detector consists of 16 × 4 SiPMs with a pixel size of 3.0 × 3.0 mm2 and a pitch of 3.2 mm. The 64 signals of each SiPM array are processed by using the TOFPET2 application-specific integrated circuit individually. All but the edge slices can be clearly resolved for the detectors with both single-ended and dual-ended readouts. The single-ended readout detector provides an average full width at half maximum (FWHM) Y (continuous direction) position resolution of 2.43 mm, Z (depth direction) position resolution of 4.77 mm, energy resolution of 25.7% and timing resolution of 779 ps. The dual-ended readout detector significantly improves the Y and Z position resolutions, slightly improves the energy and timing resolution at the cost of two photodetectors required for one detector module and provides an average FWHM Y position resolution of 1.97 mm, Z position resolution of 2.60 mm, energy resolution of 21.7% and timing resolution of 718 ps. The energy and timing resolution of the semi-monolithic scintillator detector in this work are worse than those of the segmented scintillator array detector and need to be further improved. The semi-monolithic scintillator detector described in this work reduces costs as compared to the traditional segmented scintillator array detector and reduces the edge effect as compared to the monolithic scintillator detector.
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Affiliation(s)
- Chunhui Zhang
- Center for Advanced Material Diagnostic Technology, Shenzhen Technology University, Shenzhen 518118, People's Republic of China. Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
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Lai Y, Wang Q, Zhou S, Xie Z, Qi J, Cherry SR, Jin M, Chi Y, Du J. H 2RSPET: a 0.5 mm resolution high-sensitivity small-animal PET scanner, a simulation study. Phys Med Biol 2021; 66:065016. [PMID: 33571980 DOI: 10.1088/1361-6560/abe558] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
With the goal of developing a total-body small-animal PET system with a high spatial resolution of ∼0.5 mm and a high sensitivity >10% for mouse/rat studies, we simulated four scanners using the graphical processing unit-based Monte Carlo simulation package (gPET) and compared their performance in terms of spatial resolution and sensitivity. We also investigated the effect of depth-of-interaction (DOI) resolution on the spatial resolution. All the scanners are built upon 128 DOI encoding dual-ended readout detectors with lutetium yttrium oxyorthosilicate (LYSO) arrays arranged in 8 detector rings. The solid angle coverages of the four scanners are all ∼0.85 steradians. Each LYSO element has a cross-section of 0.44 × 0.44 mm2 and the pitch size of the LYSO arrays are all 0.5 mm. The four scanners can be divided into two groups: (1) H2RS110-C10 and H2RS110-C20 with 40 × 40 LYSO arrays, a ring diameter of 110 mm and axial length of 167 mm, and (2) H2RS160-C10 and H2RS160-C20 with 60 × 60 LYSO arrays, a diameter of 160 mm and axial length of 254 mm. C10 and C20 denote the crystal thickness of 10 and 20 mm, respectively. The simulation results show that all scanners have a spatial resolution better than 0.5 mm at the center of the field-of-view (FOV). The radial resolution strongly depends on the DOI resolution and radial offset, but not the axial resolution and tangential resolution. Comparing the C10 and C20 designs, the former provides better resolution, especially at positions away from the center of the FOV, whereas the latter has 2× higher sensitivity (∼10% versus ∼20%). This simulation study provides evidence that the 110 mm systems are a good choice for total-body mouse studies at a lower cost, whereas the 160 mm systems are suited for both total-body mouse and rat studies.
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Affiliation(s)
- Youfang Lai
- Department of Physics, University of Texas at Arlington, Arlington, TX 76019, United States of America
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Prout DL, Gu Z, Shustef M, Chatziioannou AF. A digital phoswich detector using time-over-threshold for depth of interaction in PET. Phys Med Biol 2020; 65:245017. [PMID: 33202397 PMCID: PMC8382115 DOI: 10.1088/1361-6560/abcb21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We present the performance of a digital phoswich positron emission tomography (PET) detector, composed by layers of pixilated scintillator arrays, read out by solid state light detectors and an application specific integrated circuit (ASIC). We investigated the use of integrated charge from the scintillation pulses along with time-over-threshold (ToT) to determine the layer of interaction (DOI) in the scintillator. Simulations were performed to assess the effectiveness of the ToT measurements for separating the scintillator events and identifying cross-layer-crystal-scatter (CLCS) events. These simulations indicate that ToT and charge integration from such a detector provide sufficient information to determine the layer of interaction. To demonstrate this in practice, we used a pair of prototype LYSO/BGO detectors. One detector consisted of a 19 × 19 array of 7 mm long LYSO crystals (1.36 mm pitch) coupled to a 16 × 16 array of 8 mm long BGO crystals (1.63 mm pitch). The other detector was similar except the LYSO crystal pitch was 1.63 mm. These detectors were coupled to an 8 × 8 multi-pixel photon counter mounted on a PETsys TOFPET2 ASIC. This high performance ASIC provided digital readout of the integrated charge and ToT from these detectors. We present a method to separate the events from the two scintillator layers using the ToT, and also investigate the performance of this detector. All the crystals within the proposed detector were clearly resolved, and the peak to valley ratio was 11.8 ± 4.0 and 10.1 ± 2.9 for the LYSO and BGO flood images. The measured energy resolution was 9.9% ± 1.3% and 28.5% ± 5.0% respectively for the LYSO and BGO crystals in the phoswich layers. The timing resolution between the LYSO-LYSO, LYSO-BGO and BGO-BGO coincidences was 468 ps, 1.33 ns and 2.14 ns respectively. Results show ToT can be used to identify the crystal layer where events occurred and also identify and reject the majority of CLCS events between layers.
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Affiliation(s)
- David L Prout
- Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California, Los Angeles, CA, United States of America
- Shared first authorship
| | - Zheng Gu
- Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California, Los Angeles, CA, United States of America
- Institute of Biomedical Engineering, Shenzhen Bay Laboratory, Shenzhen, Guangdong Province, People's Republic of China
- Shared first authorship
| | - Max Shustef
- Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California, Los Angeles, CA, United States of America
| | - Arion F Chatziioannou
- Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California, Los Angeles, CA, United States of America
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Kuang Z, Wang X, Ren N, Wu S, Gao J, Zeng T, Gao D, Zhang C, Sang Z, Hu Z, Du J, Liang D, Liu X, Zheng H, Yang Y. Design and performance of SIAT aPET: a uniform high-resolution small animal PET scanner using dual-ended readout detectors. Phys Med Biol 2020; 65:235013. [PMID: 32992302 DOI: 10.1088/1361-6560/abbc83] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this work, a small animal PET scanner named SIAT aPET was developed using dual-ended readout depth encoding detectors to simultaneously achieve high spatial resolution and high sensitivity. The scanner consists of four detector rings with 12 detector modules per ring; the ring diameter is 111 mm and the axial field of view (FOV) is 105.6 mm. The images are reconstructed using an ordered subset expectation maximization (OSEM) algorithm. The spatial resolution of the scanner was measured by using a 22Na point source at the center axial FOV with different radial offsets. The sensitivity of the scanner was measured at center axis of the scanner with different axial positions. The count rate performance of the system was evaluated by scanning mouse-sized and rat-sized phantoms. An ultra-micro hot-rods phantom and two mice injected with 18F-NaF and 18F-FDG were scanned on the scanner. An average depth of interaction (DOI) resolution of 1.96 mm, energy resolution of 19.1% and timing resolution of 1.20 ns were obtained for the detector. Average spatial resolutions of 0.82 mm and 1.16 mm were obtained up to a distance of 30 mm radially from the center of the FOV when reconstructing a point source in 1% and 10% warm backgrounds, respectively, using OSEM reconstruction with 16 subsets and 10 iterations. Sensitivities of 16.0% and 11.9% were achieved at center of the scanner for energy windows of 250-750 keV and 350-750 keV respectively. Peak noise equivalent count rates (NECRs) of 324 kcps and 144 kcps were obtained at an activity of 26.4 MBq for the mouse-sized and rat-sized phantoms. Rods of 1.0 mm diameter can be visually resolved from the image of the ultra-micro hot-rods phantom. The capability of the scanner was demonstrated by high quality in-vivo mouse images.
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Affiliation(s)
- Zhonghua Kuang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China. Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China. Authors have contributed equally to this work
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