Design and numerical simulations of a large animal SPECT system
ZHANG Zhihan1, LIU Hui1, L�Zhenlei1, HOU Yansong2, SUN Lifeng3, WANG Shi1, WU Zhaoxia1, LIU Yaqiang1
1. Department of Engineering Physics, Tsinghua University, Beijing 100084, China; 2. Beijing NOVEL MEDICAL Equipment Ltd., Beijing 102206, China; 3. CNNC High Energy Equipment(Tianjin) Co., Ltd., Tianjin 300300, China
Abstract：This study analyzed the collimator parameters of a large animal single photon emission computed tomography (SPECT) detector. Six collimator design schemes were chosen by thoretical calculation of the spatial resolution, the sensitivity at the field of view (FOV) center and the projection overlap ratio with specified constraints. A performance evaluation method was used to evaluate the six collimator design schemes by calculating the contrast recovery coefficient (CRC) and the variance of the local impulse response of selected pixels to find the best design scheme. The imaging effect of the design scheme was verified by numerical simulations of imaging experiments of a hotrod phantom. The theoretical calculations and the numerical simulations demonstrate that the design scheme gives a spatial resolution of the hotrod phantom that is better than 3.0 mm with better than 0.03% sensitivity at the FOV center, which meets the technical requirements.
张旨晗, 刘辉, 吕振雷, 侯岩松, 孙立风, 王石, 吴朝霞, 刘亚强. 大动物SPECT系统设计与数值模拟[J]. 清华大学学报（自然科学版）, 2022, 62(12): 1875-1883.
ZHANG Zhihan, LIU Hui, L�Zhenlei, HOU Yansong, SUN Lifeng, WANG Shi, WU Zhaoxia, LIU Yaqiang. Design and numerical simulations of a large animal SPECT system. Journal of Tsinghua University(Science and Technology), 2022, 62(12): 1875-1883.
 WEISSLEDER R. Molecular imaging: Exploring the next frontier[J]. Radiology, 1999, 212(3): 609-614.  BOGDANOV JR A, MARECOS E, CHENG H C, et al. Treatment of experimental brain tumors with trombospondin-1 derived peptides: An in vivo imaging study[J]. Neoplasia, 1999, 1(5): 438-445.  JANSSEN J P, HOFFMANN J V, KANNO T, et al. Capabilities of multi-pinhole SPECT with two stationary detectors for in vivo rat imaging[J]. Scientific Reports, 2020, 10(1): 1-10.  BERG E, ZHANG X Z, BEC J, et al. Development and evaluation of mini-EXPLORER: A long axial field-of-view PET scanner for nonhuman primate imaging[J]. Journal of Nuclear Medicine, 2018, 59(6): 993-998.  CHAI P, FENG B T, ZHANG Z M, et al. NEMA NU-4 performance evaluation of a non-human primate animal PET[J]. Physics in Medicine and Biology, 2019, 64(10): 105018.  ZHANG J J, ZANNONI E M, DU Y, et al. Alpha-SPECT: Hyperspectral single photon imaging of targeted α-emission therapy[J]. Journal of Nuclear Medicine, 2019, 60(s1): 311-311.  CHERRY S R. In vivo molecular and genomic imaging: New challenges for imaging physics[J]. Physics in Medicine and Biology, 2004, 49(3): 13-48.  MA T Y, WEI Q Y, LYU Z L, et al. Self-collimating SPECT with multi-layer interspaced mosaic detectors[J]. IEEE Transactions on Medical Imaging, 2021, 40(8): 2152-2169.  HOFFMANN J V, JANSSEN J P, KANNO T, et al. Performance evaluation of fifth-generation ultra-high-resolution SPECT system with two stationary detectors and multi-pinhole imaging[J]. EJNMMI physics, 2020, 7(1): 1-15.  DAI T T, MA T Y, LIU H, et al. A high-resolution small animal SPECT system developed at Tsinghua[J]. Nuclear Science and Techniques, 2011, 22(6): 344-348.  LUKAS M, KLUGE A, BEINDORFF N, et al. Accurate Monte Carlo modeling of small-animal multi-pinhole SPECT for non-standard multi-isotope applications[J]. IEEE Transactions on Medical Imaging, 2021, 40(9): 2208-2220.  SUN L F, LYU Z L, HOU Y S, et al. System design and performance evaluation for cardiac SPECT imaging with multi-pinhole collimator[J]. Atomic Energy Science and Technology, 2021, 55(s2): 407-413. (in Chinese) 孙立风, 吕振雷, 侯岩松, 等. 多针孔心脏SPECT成像系统设计与性能评估[J]. 原子能科学与技术, 2021, 55(s2): 407-413.  ZERAATKAR N, AUER B, KALLURI K S, et al. Improvement in sampling and modulation of multiplexing with temporal shuttering of adaptable apertures in a brain-dedicated multi-pinhole SPECT system[J]. Physics in Medicine and Biology, 2021, 66(6): 065004.  WEI Q Y, WANG S, MA T Y, et al. Performance evaluation of a compact PET/SPECT/CT tri-modality system for small animal imaging applications[J]. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2015, 786: 147-154.  METZLER S D, ACCORSI R. Resolution-versus sensitivity-effective diameter in pinhole collimation: Experimental verification[J]. Physics in Medicine and Biology, 2005, 50(21): 5005-5017.  GONG K, MAJEWSKI S, KINAHAN P E, et al. Designing a compact high performance brain PET scanner-simulation study[J]. Physics in Medicine and Biology, 2016, 61(10): 3681-3697.  FESSLER J A, ROGERS W L. Spatial resolution properties of penalized-likelihood image reconstruction: Space-invariant tomographs[J]. IEEE Transactions on Image Processing, 1996, 5(9): 1346-1358.  QI J Y, LEAHY R M. Resolution and noise properties of MAP reconstruction for fully 3-D PET[J]. IEEE Transactions on Medical Imaging, 2000, 19(5): 493-506.  FESSLER J A. Mean and variance of implicitly defined biased estimators (such as penalized maximum likelihood): Applications to tomography[J]. IEEE Transactions on Image Processing, 1996, 5(3): 493-506.  VUNCKX K, BEQUÉ D, DEFRISE M, et al. Single and multipinhole collimator design evaluation method for small animal SPECT[J]. IEEE Transactions on Medical Imaging, 2007, 27(1): 36-46.  QI J Y, LEAHY R M. A theoretical study of the contrast recovery and variance of MAP reconstructions from PET data[J]. IEEE Transactions on Medical Imaging, 1999, 18(4): 293-305.  SCHMITT D, KARUTA B, CARRIER C, et al. Fast point spread function computation from aperture functions in high-resolution positron emission tomography[J]. IEEE Transactions on Medical Imaging, 1988, 7(1): 2-12.  STRUL D, SLATES R B, DAHLBOM M, et al. An improved analytical detector response function model for multilayer small-diameter PET scanners[J]. Physics in Medicine and Biology, 2003, 48(8): 979-994.  ERLANDSSON K, BUVAT I, PRETORIUS P H, et al. A review of partial volume correction techniques for emission tomography and their applications in neurology, cardiology and oncology[J]. Physics in Medicine and Biology, 2012, 57(21): 119-159.