Photon Radiosurgery System – time stability of the calibration parameters

SummaryAimThe aim of the paper is to present the time stability of the calibration parameters of a miniature 50 kV Photon Radiosurgery System used during surgical procedures to irradiate tumour beds.Materials/MethodsBefore tumour irradiation, calibration procedures were performed and individual treatment times were calculated. During quality control procedures, parameters such as probe straightness, isotropy of the beam and stability of the internal and external monitors were checked. Also output dose rate was measured.ResultsThe average values of the parameters measured, and percentage deviations (1 SD) thereof, were as follows: probe straightness 0.035 mm (22.1%); isotropy of the beam 5.72% (3.5%); internal monitor reading 8.182 E4 104 (0.7%); external monitor reading 2.932 Hz (3.1%); output dose rate 2.731 Gy/min (1.8%).ConclusionsHigh stability of the calibration parameters was observed. Measurement of probe deviation is a necessary condition in each radiotherapy procedure