Effective cooling method for a SiPM based brain PET system

Abstract

Silicon photomultipliers (SiPM) is useful to make a compact and efficient positron emission tomography (PET) system. Like other solid state device, SiPM is also temperature sensitive. In PET system it is difficult to cool the SiPM to a certain temperature. For this reason, it is not possible to get full advantages of PET system based on SiPM. Most of the invented cooling techniques are limited to an individual module of a detector. In this study we present a new technique to cool SiPM as well as application-specific integrated circuit (ASIC) part of PET system. Each module of our considered PET system has 8×8 array of two SiPM and two ASIC. In our KAIST PET system most of the heat produce in ASICs part. To cool ASICs we use water, and to cool SiPMs we use air. By using water, it was possible to cool ASIC to 14.383°C with 0.005kg/s flow rate of water. To reduce complexity and extract heat from SiPM, we consider air as cooler, which is passed behind the SiPM array. With this technique we find, maximum temperature of SiPMs is 16.2°C and minimum temperature of that is 12°C. Various study shows, dark current and gain of SiPM varies slightly within the temperature range of 12°C - 16°C. As we are able to maintain our SiPM temperature within this temperature range, it is possible to get good image from the proposed system and it will give a new dimension to have a more effieient and compact PET system.