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Development of depth encoding small animal PET detectors using dual‐ended readout of pixelated scintillator arrays with Si PM s
Author(s) -
Kuang Zhonghua,
Sang Ziru,
Wang Xiaohui,
Fu Xin,
Ren Ning,
Zhang Xianming,
Zheng Yunfei,
Yang Qian,
Hu Zhanli,
Du Junwei,
Liang Dong,
Liu Xin,
Zheng Hairong,
Yang Yongfeng
Publication year - 2018
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1002/mp.12722
Subject(s) - lyso , silicon photomultiplier , detector , scintillator , image resolution , optics , photomultiplier , materials science , avalanche photodiode , photodetector , optoelectronics , scanner , resolution (logic) , photodiode , physics , computer science , artificial intelligence
Purpose The performance of current small animal PET scanners is mainly limited by the detector performance and depth encoding detectors are required to develop PET scanner to simultaneously achieve high spatial resolution and high sensitivity. Among all depth encoding PET detector approaches, dual‐ended readout detector has the advantage to achieve the highest depth of interaction ( DOI ) resolution and spatial resolution. Silicon photomultiplier (Si PM ) is believed to be the photodetector of the future for PET detector due to its excellent properties as compared to the traditional photodetectors such as photomultiplier tube ( PMT ) and avalanche photodiode ( APD ). The purpose of this work is to develop high resolution depth encoding small animal PET detector using dual‐ended readout of finely pixelated scintillator arrays with Si PM s. Methods Four lutetium‐yttrium oxyorthosilicate ( LYSO ) arrays with 11 × 11 crystals and 11.6 × 11.6 × 20 mm 3 outside dimension were made using ESR , Toray and Ba SO 4 reflectors. The LYSO arrays were read out with Hamamatsu 4 × 4 Si PM arrays from both ends. The Si PM array has a pixel size of 3 × 3 mm 2 , 0.2 mm gap in between the pixels and a total active area of 12.6 × 12.6 mm 2 . The flood histograms, DOI resolution, energy resolution and timing resolution of the four detector modules were measured and compared. Results All crystals can be clearly resolved from the measured flood histograms of all four arrays. The Ba SO 4 arrays provide the best and the ESR array provides the worst flood histograms. The DOI resolution obtained from the DOI profiles of the individual crystals of the four array is from 2.1 to 2.35 mm for events with E > 350 keV. The DOI ratio variation among crystals is bigger for the Ba SO 4 arrays as compared to both the ESR and Toray arrays. The Ba SO 4 arrays provide worse detector based DOI resolution. The photopeak amplitude of the Toray array had the maximum change with depth, it provides the worst energy resolution of 21.3%. The photopeak amplitude of the Ba SO 4 array with 80 μ m reflector almost doesn't change with depth, it provides the best energy resolution of 12.9%. A maximum timing shift of 1.37 ns to 1.61 ns among the corner and the center crystals in the four arrays was obtained due to the use of resistor network readout. A crystal based timing resolution of 0.68 ns to 0.83 ns and a detector based timing resolution of 1.26 ns to 1.45 ns were obtained for the four detector modules. Conclusions Four high resolution depth encoding small animal PET detectors were developed using dual‐ended readout of pixelated scintillator arrays with Si PM s. The performance results show that those detectors can be used to build a small animal PET scanner to simultaneously achieve uniform high spatial resolution and high sensitivity.