Göttingen 2025 – wissenschaftliches Programm

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ST: Fachverband Strahlen- und Medizinphysik

ST 6: Medical Imaging and Treatment Monitoring

ST 6.2: Vortrag

Donnerstag, 3. April 2025, 11:15–11:30, ZHG003

Towards Clinical Use of Range Monitoring in Heavy-Ion Therapy — •Sebastian Schroeder¹, Devin Hymers¹, Olga Bertini², Johann Heuser², Joerg Lehnert², Christian Joachim Schmidt², and Dennis Muecher¹ — ¹Institute for Nuclear Physics, University of Cologne, Cologne, Germany — ²GSI, Darmstadt, Germany

Interaction Vertex Imaging (IVI) is a proposed method for online range monitoring in heavy-ion therapy which will help ensure correct Bragg peak (BP) positioning, and could act as a safety interlock, pausing irradiation if incorrect BP depth is detected. IVI tracks secondary ions produced by beam-patient interactions, and calculates the origin of each secondary ion as the closest approach of its track to the treatment beam. This data is used to determine BP range shifts with sub-mm precision. The tracking hardware is a purpose-built system, using sensors developed by GSI for the Compressed Baryonic Matter experiment. These highly segmented, double sided silicon strip detectors have a 58 µm pitch, and cover a large sensitive area of up to 72 cm². These detectors are coupled to readout electronics capable of count rates up to 250 kHz per segment. To test IVI with this system under clinical conditions, measurements were performed at the Heidelberg Ionenstrahl-Therapiezentrum. PMMA phantoms of 16 cm and 32 cm diameter were irradiated at BP depths of 27-80 mm and 27-160 mm respectively. A 9 mm air gap was also introduced in the phantom, as a first step towards measuring inhomogeneities. These results, as well as next steps towards anthropomorphic phantoms, will be discussed.

Keywords: Range Monitoring; Heavy-Ion Therapy; Interaction Vertex Imaging; Particle Tracking; Silicon Strip Detectors