Erlangen 2026 – wissenschaftliches Programm

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ST: Fachverband Strahlen- und Medizinphysik

ST 5: Focus Session: Range Verification in Particle Therapy

ST 5.4: Hauptvortrag

Donnerstag, 19. März 2026, 12:30–13:00, KH 01.013

Helium as a Range Probe in Carbon-Ion Therapy: From Concept to Mixed-Beam Experiments — •Lennart Volz for the PROMISE collaboration — GSI Helmholtz Zentrum für Schwerionenforschnung GmbH, Darmstadt, Germany

Carbon ion therapy offers superior dose conformity compared to conventional radiotherapy, but its full potential is limited by the lack of real-time, in-beam range verification. The PROMISE project (ERC Grant No. 101124273) investigates a novel approach based on mixed ion beams to enable simultaneous treatment delivery and particle-based imaging. Carbon and helium ions have nearly identical charge-to-mass ratios and can therefore be accelerated simultaneously to the same velocity in a synchrotron. At equal velocity, helium ions have a threefold larger range than carbon ions. While the carbon component delivers the therapeutic dose, the helium ions act as a low-dose imaging probe. This contribution reports on the first experimental realization of mixed beam range verification and imaging at GSI's SIS18 synchrotron. Experiments on a lung-cancer-mimicking setup reveal that a mixed beam enables tracking a spherical tumor at sub-millimeter accuracy, with high sensitivity to range changes down to <0.1% of the beam range using a particle imaging scintillator detector. Simulations on patient CT data are used to explore the clinical potential of this technique. This work represents an important step toward fully image-guided heavy-ion therapy.

Keywords: Mixed ion beams; Carbon ion therapy; Helium ion imaging; Portal imaging; Range monitoring