Regensburg 2019 – wissenschaftliches Programm

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ST: Fachverband Strahlen- und Medizinphysik

ST 3: Gamma Imaging

ST 3.4: Vortrag

Dienstag, 2. April 2019, 11:00–11:15, Kunsthalle

Evaluation and Optimization of a Semi-Monolithic Detector Concept in Positron Emission Tomography (PET) — •Michael Hammerath, Florian Müller, Christian Gorjaew, David Schug, and Volkmar Schulz — RWTH Aachen University, Physics of Molecular Imaging Systems, Aachen, Germany

PET is a medical imaging technique using positron-emitting tracers to examine a patient’s metabolism. Two γ-particles - created by electron-positron annihilation - are detected by scintillation detectors. The impinging position, arrival time, and energy of the γ-particles are measured to reconstruct the tracer distribution.

We present a novel semi-monolithic detector concept to combine the intrinsic depth of interaction (DOI) information of a monolithic scintillator with the high photon density of segmented scintillator arrays. One detector block consists of 8 LYSO slabs of dimensions 3.9 mm x 32 mm and 12 mm or 19 mm height. The slabs were optically coupled to a digital SiPM, covering a single row of pixels each. The detector block under test was stepwise irradiated with a fan beam collimator setup. Impinging γ-events were positioned separately along the planar and DOI direction employing the supervised machine learning algorithm gradient tree boosting. Spatial resolutions of 1.2 mm and 1.9 mm for the planar direction as well as 1.8 mm and 2.7 mm for the DOI direction were achieved for the crystals of 12 mm and 19 mm height. A dedicated energy calibration was used to determine the energy resolution. For first-photon trigger, energy resolutions of 12.1% for slabs of 12 mm and 11.1% for slabs of 19 mm height were achieved.