title: A temperature-dependent gain control system for improving the stability of Si-PM-based PET systems.
abstract: 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.
authors.affiliation: Kobe City College of Technology, Kobe, Japan. s-yama@kobe-kosen.ac.jp
authors.forename: Seiichi
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Junkichi
authors.initials: J
authors.lastname: Satomi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Watabe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Watabe
authors.forename: Yasukazu
authors.initials: Y
authors.lastname: Kanai
authors.forename: Masao
authors.initials: M
authors.lastname: Imaizumi
authors.forename: Eku
authors.initials: E
authors.lastname: Shimosegawa
authors.forename: Jun
authors.initials: J
authors.lastname: Hatazawa
mesh_terms: D049268:Positron-Emission Tomography / Q000295:instrumentation*; D012825:Silicon; D013696:Temperature
chemical_list: D012825:Silicon