A study on the temperature characteristics of LYSO PET detector

In order to achieve the best performance of a LYSO PET scanner, the temperature dependence of LYSO crystals was studied in order to understand its impact on the collected light output, energy resolution, transit time and timing resolution. With eight LYSO block detectors, the temperature dependence was measured from room temperature, 22, to 58 °C. The analysis showed that collected light output was reduced by 0.85% per degree C at the room temperature, 22 °C. Since it is known that bi-alkali photocathode shows 0.4% sensitivity loss per degree C in average, the rest, 0.45%, can be contributed to LYSO light output reduction as temperature increases. Energy resolution was also linearly degraded by 0.56% per degree C. Also, the timing properties of LYSO block were discussed. In order to check the integrity of the measurement, the exact measurement was repeated on BGO block detectors for comparison.