A PET daily quality control method using background radiation of LYSO crystal

In the routine use of PET (Positron Emission Tomography), daily quality control (QC) plays a crucial role in the normal operation of the system. To facilitate more convenient and safer PET QC, in this article, we utilize the inherent radioactive isotope Lu176 in the scintillation crystal LYSO to detect and correct important stability indicators of PET systems, such as energy calibration status and time calibration status. To validate the effectiveness of this new method, we conducted verification on the PET/CT system uMI Panorama GS, produced by United Imaging Healthcare. The Panorama GS has an axial length of 148.2 cm, and traditional radioactive source QC methods require either an extremely long radioactive source phantom or multiple movements of the radioactive source, which is very inconvenient. We compared the results from background detection with those from radioactive source detection and subsequently corrected the system’s calibration status based on the background results. The results showed that the energy detection accuracy per crystal can reach ± 1 ADC channel at 511 Kev. The NEMA2018 time resolution improved from 251.5 ps to 189.5 ps, which is very close to the actual time resolution of 188.9 ps, demonstrating the high precision of this method. Our next step is to continue studying the effects of background correction on system sensitivity, image quality, and other factors.