Quality Assurance test of the real-time beam tracking system

For radiotherapy with external beams, quality assurance (QA) of beam delivery is mandatory. Dynamical irradiation which changes parameters of beam delivery devices during the irradiation has to be assessed with a great caution. At GSI a dynamic beam delivery system, so called beam tracking system [1] was developed and integrated into the GSI therapy system [2] to irradiate moving tumours with ion beams. The beam tracking system can control ion beams laterally with the scanning magnets of the rasterscan system [2] and longitudinally with a range shifter depending on the real-time information of target motion and scanning points based on a pre-calculated beam displacements from time-resolved treatment planning (4DTP) [3]. A method of beam tracking QA was investigated and experimentally tested by measuring dose delivered with beam tracking for a patient treatment plan.