Calibration Procedure for a Continuous Miniature Crystal Element (cMiCE) Detector

We report on methods to speed up the calibration process for a continuous miniature crystal element (cMiCE) detector. Our cMiCE detector is composed of a 50-mm by 50-mm by 8-mm-thick monolithic LYSO crystal coupled to a 64-channel, flat-panel photomultiplier tube (PMT). It achieves an average intrinsic spatial resolution of ~1.4 mm full width at half maximum (FWHM) over the useful face of the detector through the use of a statistics-based positioning algorithm. A drawback to the design is the length of time it takes to calibrate the detector. We report on three methods to speed up this process. The first method is to use multiple point fluxes on the surface of the detector to calibrate different points of the detector from a single data acquisition. A special multisource device that can produce up to 16 point fluxes has been custom designed for this purpose. The second scheme is to characterize the detector with coarser sampling and use interpolation to create lookup tables with the desired detector binning (e.g., 0.253 mm). The intrinsic spatial resolution performance was investigated for sampling intervals of 1.013, 2.026, 3.039, and 4.052 mm. The third method is to adjust the point flux diameter by varying the geometry of the setup. A larger point flux diameter will increase the coincidence counting rate. The average intrinsic spatial resolution was 1.38 mm FWHM using four point fluxes, 1.013 mm detector sampling, and ~0.5 mm point flux on the surface of the detector. The average intrinsic spatial resolution increased slightly to 1.45 mm FWHM when using 16 point fluxes with a detector sampling of 3.039 mm. Adjusting the point flux size degraded the intrinsic spatial resolution the most (~9%) and provided the smallest speed up factor. In conclusion using 16 point fluxes and a sampling interval of 3.039 mm, the characterization time for a cMiCE detector can be reduced by a factor of 144 with minimal impact on the intrinsic spatial resolution of the detector.