  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%.
