Heidelberg 2022 – wissenschaftliches Programm

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ST: Fachverband Strahlen- und Medizinphysik

ST 1: Radiation therapy I

ST 1.4: Vortrag

Montag, 21. März 2022, 14:45–15:00, ST-H4

Granularity and Photomultiplier studies for Prompt Gamma Spectra in Proton Therapy — •Olga Novgorodova and Arno Straessner — IKTP TU Dresden, Dresden, Germany

Prompt gammas (PG) in proton therapy are one of the promising techniques for non-invasive measurements of in-vivo proton range and it is already in implementation in clinical research. It can be based on time or spectral measurements. We concentrate on the spectral properties by developing systems measuring PG in the range 2-8 MeV, which already were shown to provide a time resolution of about 100 ns. A big problem in the recording prompt gammas during the irradiation of patients is the data load due to the size of the crystal. By decreasing the size of the crystals and forming them into the matrices the load to each channel can be reduced and more PGs can be detected. We are investigating different sizes and types of crystals to find an optimum. Availability on the market and the choice of photomultipliers also plays an important role for the granularity of crystals. Three different types of photomultipliers were used: a regular PMT, MAPMT and several SiPMs, which have high photon detection efficiency, good time resolution, low bias voltage and can operate in magnetic fields. For the SiPMs, PETsys readout electronics was used. In the presentation we present effects due to crystal types and sizes, and compare different photomultipliers and read out systems.