[Radiophysical characteristics of different detectors for use in dosimetry].

The present study investigated the radiophysical influences on the measurement of dosimetry basic data, attributable to field size, photon energy and detector type. A natural diamond detector, two ionisation chambers, different Si-diodes and a EBT-Gafchromic film were studied for this purpose. The characteristics of the detectors were investigated with regard to the measurement of output factors, lateral beam profiles and relative depth-dose curves for narrow and wide photon beams of 15 MV Significant differences in output factors were obtained with different detectors. For narrow fields, the natural diamond detector and the diodes PTW-60012 and SCX_WH-PFD measured output factors close to those of the EBT-Gafchromic film. The output facto rfor large fields was overestimated by the unshielded diode PTW 60012 and the PinPoint-chamber PTW-31006 because of their over-response to scattered photons. The relative depth dose distributions for wide beams at large depths agree well for the diamond, the ionisation chambers and the shielded Diode SCX_ WH-PFD and PTW-60008, while the measured dose was overestimated by an unshielded diode PTW-60012. Considering the influence due to the sensitive materials and the construction of the detectors the manufacturers of dosimeters have specified the application ranges for the various types of detectors.