A temperature-dependent gain control system for improving the stability of Si-PM-based PET systems
A temperature-dependent gain control system for improving the stability of Si-PM-based PET systems
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DOI：
10.1088/0031-9155/56/9/015
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发表时间：
2011-05
影响因子：
3.5
通讯作者：
S. Yamamoto;Junkichi Satomi;T. Watabe;H. Watabe;Y. Kanai;M. Imaizumi;E. Shimosegawa;J. Hatazawa
中科院分区：
文献类型：
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作者：
S. Yamamoto;Junkichi Satomi;T. Watabe;H. Watabe;Y. Kanai;M. Imaizumi;E. Shimosegawa;J. Hatazawa
硅光电倍增管（Si-PM）具有体积小、增益高、对静磁场灵敏度低等优点，是一种很有前途的光电探测器。Si-PM的一个缺点是其具有显著的温度依赖性增益，这对基于Si-PM的PET系统的稳定性造成了问题。为了减少这个问题，我们开发和测试了一个温度依赖的增益控制系统的硅-PM为基础的PET系统。该系统由温度计、模数转换器、个人计算机、数模转换器和PET系统重量求和板中的可变增益放大器组成。测量了硅永磁阵列的温度特性，并将计算出的校正因子发送到可变增益放大器。如果没有这种校正，块检测器的温度相关峰值通道偏移在20 °C至35 °C范围内为−55%。经校正后，峰通道变化校正在± 8%以内。使用Na-22点源同时监测室温来测量基于Si-PM的PET系统的符合计数率。在没有校正的情况下，对于1.5° C的温度变化，计数率随室温反向变化10%。经校正后，计数率变化减小到3.7%以内。这些结果表明，开发的温度依赖性增益控制系统可以有助于提高硅PM基PET系统的稳定性。
The silicon-photomultiplier (Si-PM) is a promising photodetector for the development of new PET systems due to its small size, high gain and relatively low sensitivity to the static magnetic field. One drawback of the Si-PM is that it has significant temperature-dependent gain that poses a problem for the stability of the Si-PM-based PET system. To reduce this problem, we developed and tested a temperature-dependent gain control system for the Si-PM-based PET system. The system consists of a thermometer, analog-to-digital converter, personal computer, digital-to-analog converter and variable gain amplifiers in the weight summing board of the PET system. Temperature characteristics of the Si-PM array are measured and the calculated correction factor is sent to the variable gain amplifier. Without this correction, the temperature-dependent peak channel shifts of the block detector were −55% from 20 °C to 35 °C. With the correction, the peak channel variations were corrected within ±8%. The coincidence count rate of the Si-PM-based PET system was measured using a Na-22 point source while monitoring the room temperature. Without the correction, the count rate inversely changed with the room temperature by 10% for 1.5° C temperature changes. With the correction, the count rate variation was reduced to within 3.7%. These results indicate that the developed temperature-dependent gain control system can contribute to improving the stability of Si-PM-based PET systems.