Regensburg 2019 – wissenschaftliches Programm

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ST: Fachverband Strahlen- und Medizinphysik

ST 3: Gamma Imaging

ST 3.5: Vortrag

Dienstag, 2. April 2019, 11:15–11:30, Kunsthalle

Timing Performance of a Detector Based on Semi-Monolithic Scintillators for Positron Emission Tomography (PET) — •Christian Gorjaew, Florian Mueller, Michael Hammerath, David Schug, and Volkmar Schulz — RWTH Aachen University, Physics of Molecular Imaging Systems, Aachen, Germany

PET uses a β⁺-decaying tracer material to resolve metabolic processes in an organism by detecting the two γ-photons of the e⁺e⁻-annihilation along a line of response (LOR) with a ring-shaped arrangement of scintillation detectors. Precise time information is utilized to enhance the signal-to-noise ratio by restricting the annihilation position to a smaller region on the LOR (Time-of-Flight PET). Among others, the scintillator crystal’s geometry can have significant impact on the performance of the detector, especially on the timing performance. Hence, we investigated the time resolution of a novel detector concept based on semi-monolithic scintillator slabs. This concept aims to combine the good energy and time resolution of pixelated scinitllators and the precise 3D-positioning accuracy of monolithic ones. We studied two detectors built up of 12 mm and 19 mm high LYSO scintillators coupled to a digital SiPM (PDPC, DPC 3200-22-44) and developed a time calibration. The achieved time resolution is reported. After correction of runtime differences caused by electronics and scintillator, coincidence resolving times down to 226 ps FWHM could be reached, approaching values of the best PET systems on the market. Furthermore, we implemented a maximum likelihood algorithm to estimate the interaction time of the annihilation photons more precisely.