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ST: Fachverband Strahlen- und Medizinphysik

ST 2: Detectors for Treatment Monitoring

ST 2.4: Talk

Tuesday, March 17, 2026, 17:00–17:15, KH 01.013

Absorption Point Reconstruction and Energy Measurement in Scintillation Material for Medical Imaging — Atharva Bahekar, Yazeed Balasmeh, Ivor Fleck, Mara Fries, •Lars Maczey, and Devanshi Mehta — Experimentelle Teilchenphysik, Center for Particle Physics Siegen, Universität Siegen

Scintillators are central to many imaging technologies that rely on gamma detection, where accurately reconstructing both the photon's absorption point and deposited energy is essential. The work presented here is motivated by the Compton camera project at the University of Siegen but is applicable to other imaging modalities in medicine.

This talk summarises results from measurements using inorganic scintillation crystals such as GAGG and LGSO coupled to SiPMs from Broadcom and Hamamatsu, with signal acquisition performed via the TOFPET v2c ASIC from PETsys Electronics. Several methods for reconstructing the absorption point are compared, including the centroid method, maximum-likelihood fitting and a machine-learning approach. Challenges encountered in achieving a reliable energy calibration are discussed as well as measurements of the depth of interaction (DOI) using a double-sided SiPM readout. Finally, I present and discuss different design strategies for the scintillator layer, ranging from a segmented crystal array to a monolithic crystal approach, and for the SiPM layer, ranging from small-sized analogue SiPM arrays to large-area position-sensitive SiPMs.

Keywords: Medical imaging; Compton camera; Inorganic scintillator; Absorption point reconstruction; Silicon photomultiplier