A new module-level parameter interfusion ratio (IR) to evaluate the performance of PET detector block

Abstract

A high resolution detector made from 2D modular arrays of scintillation crystals is being developed for our small animal position emission tomography (MicroPET). Their characteristic flood field response (or flood histogram) has been segmented to Crystal Look-up table (CLT), which defines the matching relation between signal position of a detected event to a corresponding detector pixel location. Whether each annihilation event could match a well-separated pixel position in CLT, plays a direct role in imaging quality and brings significant influence to the gantry overall performance. Existing estimation parameters, such as photopeak positions, energy resolution, uniformity of counts cannot be readily adapted for quantitatively evaluate such module-level performance. In this paper, we present an estimation parameter Interfusion Ratio (IR) to evaluate of the level of miscoding. With the help of IR, we quantitatively compare the performance of different types of scintillator, different glued reflector types of crystals, different LUT of detectors. The running performance evaluation of electrical system after 72 hours without baseline correction is then being quantitatively evaluated using Interfusion Ratio, showing that not only it could quantitatively evaluate the LUT segmentation performance, but also assess the performance of electrical system. Furthermore, We establish the relationship between module-level parameter Interfusion Ratio (IR) and the systemlevel parameter intrinsic spatial resolution FWHM.