One-Pair Measurement System for Efficient Imaging Performance Evaluation of Prototype DOI-PET Detectors

DOI-PET detectors can provide good imaging performance even in the peripheral region of the PET FOV. In the development of DOI-PET detectors, one of the important steps toward their practical use is an evaluation of imaging performance such as the spatial resolution measured by using a point source and a one-pair system which simulates actual PET geometries. Because the DOI-PET detectors have an extended FOV compared with conventional detectors, evaluation including the region from the center to the periphery close to the detector ring is required to show their advanced performance for uniform spatial resolution. In this study, we proposed a one-pair system that can simulate an arbitrary ring diameter and acquire projection data efficiently by cutting unnecessary combinations according to the position of the point source. When we compared results by the full measurement scheme, the proposed system and our measuring scheme could significantly reduce the measurement time especially for a large ring size such as used in brain PET scanners. We used the system to evaluate the X'tal cube PET detector with a 2 mm crystal array arranged in a simulated PET geometry with the ring radius of 73 mm and 18 detector blocks. The results showed that uniform spatial resolution was achieved even in the peripheral region and measurements were obtained semi-automatically in a short time.