Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2011, Vol. 22 ›› Issue (4): 224-229 doi: 10.13538/j.1001-8042/nst.22.224-229


Influence factors of two dimensional position map on photomultiplier detector block designed by quadrant sharing technique

WEI Qingyang WANG Shi Ma Tianyu MA Fei DAI Tiantian XU Tianpeng WU Zhaoxia JIN Yongjie LIU Yaqiang   

  1. Key Laboratory of Particle & Radiation Imaging (Tsinghua University),Ministry of Education,Department of Engineering Physics,Tsinghua University,Beijing 100084,China
WEI Qingyang, WANG Shi, Ma Tianyu, MA Fei, DAI Tiantian, XU Tianpeng, WU Zhaoxia, JIN Yongjie, LIU Yaqiang. Influence factors of two dimensional position map on photomultiplier detector block designed by quadrant sharing technique.Nuclear Science and Techniques, 2011, 22(4): 224-229     doi: 10.13538/j.1001-8042/nst.22.224-229


The position decoding accuracy and the spatial resolution of positron emission tomography detectors are greatly influenced by the performance of the two-dimensional position map,including the gain uniformity of photomultiplier tube (PMT),the baseline offset of the PMT signals and the accuracy of analogue to digital converter (ADC).In this work,a PMT-quadrant sharing detector was designed.Two data acquisition platforms are employed to conduct the influence factors on the two-dimensional position map performances,one was that the waveforms of the PMT signals were scanned by the sequence acquisition mode based on the oscilloscope of LeCroy waveRunner 204MXi-A,and another was a self-developed high speed ADC data acquisition module.Results show that the event decoding positions were concentrated on the PMT with higher gain,the position map was distorted at the baseline offset of signal,and the cross-line artifacts were caused by the insufficient ADC sampling bit for a larger size position map.All the parameters need be adjusted properly to stabilize a real system,and the flexible oscilloscope platform can be used to design the detector block and the other platform with high ADC accuracy.Likely,the electrical circuit with a proper ADC accuracy adjusts the PMT gains and baseline offsets.

Key words: PMT-quadrant-sharing, Two-dimensional position map, Gain uniformity, Baseline offset, Analogue to digital converter accuracy