title: Light-Sharing Interface for dMiCE Detectors using Sub-Surface Laser Engraving.
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 mmˆ3 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.
authors.affiliation: University of Washington Department of Radiology, Seattle, WA USA.
authors.forename: William C J
authors.initials: WC
authors.lastname: Hunter
authors.affiliation: University of Washington Department of Radiology, Seattle, WA USA.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Miyaoka
authors.affiliation: University of Washington Department of Radiology, Seattle, WA USA.
authors.forename: Lawrence
authors.initials: L
authors.lastname: MacDonald
authors.affiliation: University of Washington Department of Radiology, Seattle, WA USA.
authors.forename: Wendy
authors.initials: W
authors.lastname: McDougald
authors.affiliation: University of Washington Department of Radiology, Seattle, WA USA.
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Lewellen