Title :
Light-sharing interface for dMiCE detectors using sub-surface laser engraving
Author :
Hunter, William C. J. ; Miyaoka, Robert S. ; MacDonald, Lawrence ; McDougald, Wendy ; Lewellen, Thomas K.
Author_Institution :
Dept. of Radiol., Univ. of Washington, Seattle, WA, USA
fDate :
Oct. 27 2013-Nov. 2 2013
Abstract :
We have previously reported on dMiCE, a method of resolving depth or interaction (DOI) in a pair of discrete crystals by encoding light sharing properties as a function of depth in the interface of this crystal-element pair. A challenge for this method is the cost and repeatability of interface treatment for a crystal pair. In this work, we report our preliminary results on using sub-surface laser engraving (SSLE) as a means of forming this depth-dependent interface in a dMiCE detector. A surplus first-generation SSLE system was used to create a partially reflective layer 100-microns thick at the boundary between two halves of a 1.4-by-2.9-by-20 mm^3 LYSO crystal. The boundary of these paired crystal elements was positioned between two 3-mm wide Geiger-Müller avalanche photodiodes from Hamamatsu. The responses of these two photodetectors were acquired for an ensemble of 511-keV photons collimated to interact at a fixed depth in just one crystal element. Interaction position was then varied to measure detector response as a function of depth, which was then used to maximum-likelihood positions events. Despite use of sub-optimal SSLE processing we found an average DOI resolution of 3.4 mm for front-sided readout and 3.9 mm for back-sided readout. We expect DOI resolution can be improved significantly by optimizing the SSLE process and pattern.
Keywords :
Geiger counters; avalanche photodiodes; digital readout; laser materials processing; maximum likelihood estimation; photodetectors; scintillation counters; Geiger-Muller avalanche photodiodes; LYSO; SSLE; back-sided readout; dMiCE detectors; depth-dependent interface; depth-of-interaction; discrete scintillation detector; electron volt energy 511 keV; front-sided readout; light sharing properties; light-sharing interface; maximum-likelihood positions; photodetectors; subsurface laser engraving; Calibration; Crystals; Detectors; Optical coupling; Optical films; Optical sensors; Photodetectors;
Conference_Titel :
Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2013 IEEE
Conference_Location :
Seoul
Print_ISBN :
978-1-4799-0533-1
DOI :
10.1109/NSSMIC.2013.6829407