Time-encoded imaging is useful for identifying potential special nuclear materials and other radioactive sources at a distance.In this study,a large field-of-view time-encoded imager was developed for gamma-ray and ne...Time-encoded imaging is useful for identifying potential special nuclear materials and other radioactive sources at a distance.In this study,a large field-of-view time-encoded imager was developed for gamma-ray and neutron source hotspot imaging based on a depth-of-interaction(DOI)detector.The imager primarily consists of a DOI detector system and a rotary dual-layer cylindrical coded mask.An EJ276 plastic scintillator coupled with two SiPMs was designed as the DOI detector to increase the field of view and improve the imager performance.The difference in signal time at both ends and the log of the signal amplitude ratio were used to calculate the interaction position resolution.The position resolution of the DOI detector was calibrated using a collimated Cs-137 source,and the full width at half maximum of the reconstruction position of the Gaussian fitting curve was approximately 4.4 cm.The DOI detector can be arbitrarily divided into several units to independently reconstruct the source distribution images.The unit length was optimized via Am-Be source-location experiments.A multidetector filtering method is proposed for image denoising.This method can effectively reduce image noise caused by poor DOI detector position resolution.The vertical field of view of the imager was(-55°,55°)when the detector was placed in the center of the coded mask.A DT neutron source at 20 m standoff could be located within 2400 s with an angular resolution of 3.5°.展开更多
Purpose We developed a low-complexity,high-resolution depth-of-interaction(DOI)capable positron emission tomography(PET)detector and tested its performance to prove that it can be applied to practical PET instruments....Purpose We developed a low-complexity,high-resolution depth-of-interaction(DOI)capable positron emission tomography(PET)detector and tested its performance to prove that it can be applied to practical PET instruments.Methods The detector module consists of a 24×24 LYSO crystal matrix,each with dimension of 1.04×1.04×15mm^(3),optically coupled to an 8×8 SiPM photo-sensor array with TOFPET2 ASIC single-ended readout.By only adding a light guide at the top of the crystal to reflect scintillation light back to the SiPM array,the continuous DOI information is extracted using a light sharing and redirection encoding method without adding system complexity.Results The crystal array with 9-to-1 coupling between scintillators and photo-sensors can be clearly separated in the flood image.The other detector performance in terms of DOI resolution,energy resolution and coincidence time resolution are measured on average as 4.1 mm,15.0%and 432 ps,respectively.Conclusion The test results confirm that the light sharing and redirection DOI encoding method can provide reasonably high DOI resolution without deteriorating other performance,even for highly pixelated PET detectors readout with commercially available ASIC chip.It has great potential for applications in future pre-clinical and organ-dedicated PET scanners.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11975121,12205131)the Fundamental Research Funds for the Central Universities(No.lzujbky-2021-sp58)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX22_0354)。
文摘Time-encoded imaging is useful for identifying potential special nuclear materials and other radioactive sources at a distance.In this study,a large field-of-view time-encoded imager was developed for gamma-ray and neutron source hotspot imaging based on a depth-of-interaction(DOI)detector.The imager primarily consists of a DOI detector system and a rotary dual-layer cylindrical coded mask.An EJ276 plastic scintillator coupled with two SiPMs was designed as the DOI detector to increase the field of view and improve the imager performance.The difference in signal time at both ends and the log of the signal amplitude ratio were used to calculate the interaction position resolution.The position resolution of the DOI detector was calibrated using a collimated Cs-137 source,and the full width at half maximum of the reconstruction position of the Gaussian fitting curve was approximately 4.4 cm.The DOI detector can be arbitrarily divided into several units to independently reconstruct the source distribution images.The unit length was optimized via Am-Be source-location experiments.A multidetector filtering method is proposed for image denoising.This method can effectively reduce image noise caused by poor DOI detector position resolution.The vertical field of view of the imager was(-55°,55°)when the detector was placed in the center of the coded mask.A DT neutron source at 20 m standoff could be located within 2400 s with an angular resolution of 3.5°.
基金This work was supported by the National Natural Science Foundation of China[Grant Number 11735013].
文摘Purpose We developed a low-complexity,high-resolution depth-of-interaction(DOI)capable positron emission tomography(PET)detector and tested its performance to prove that it can be applied to practical PET instruments.Methods The detector module consists of a 24×24 LYSO crystal matrix,each with dimension of 1.04×1.04×15mm^(3),optically coupled to an 8×8 SiPM photo-sensor array with TOFPET2 ASIC single-ended readout.By only adding a light guide at the top of the crystal to reflect scintillation light back to the SiPM array,the continuous DOI information is extracted using a light sharing and redirection encoding method without adding system complexity.Results The crystal array with 9-to-1 coupling between scintillators and photo-sensors can be clearly separated in the flood image.The other detector performance in terms of DOI resolution,energy resolution and coincidence time resolution are measured on average as 4.1 mm,15.0%and 432 ps,respectively.Conclusion The test results confirm that the light sharing and redirection DOI encoding method can provide reasonably high DOI resolution without deteriorating other performance,even for highly pixelated PET detectors readout with commercially available ASIC chip.It has great potential for applications in future pre-clinical and organ-dedicated PET scanners.
