Medical Physics Commissioning

The medical commissioning is an important step to bring a particle gantry into clinical operation for tumour treatments. This involves the parametrization and characterization of all relevant systems including the beam delivery, the patient table, the imaging systems and the connection to all required software components. This article is limited to necessary tasks for the beam delivery system of a pencil beam scanning system. Usually the commissioning starts with the characterization of the unscanned beam and the calibration of the beam energy. The following steps are the parametrization of the scanning system, the commissioning of the beam position monitoring system and characterization of the spot size, all requiring precisions better than 1 mm. The commissioning effort for these tasks depends also on the gantry topology. Finally, the calibration of the dose measurement system ensures that any dose distribution can be delivered with an absolute precision better than 1%.