PTW-diamond detector: Dose rate and particle type dependence

In this paper the suitability of a PTW natural diamond detector (DD) for re lative and reference dosimetry of photon and electron beams, with dose per pulse between 0.068 mGy and 0.472 mGy, was studied and the results were com pared with those obtained by a stereotactic silicon detector (SFD). The res ults show that, in the range of the examined dose per pulse the DD sensitiv ity changes up to 1.8% while the SFD sensitivity changes up to 4.5%. The fi tting parameter, a, used to correct the dose per pulse dependence of solid state detectors, was Delta = 0.993+/-0.002 and Delta = 1.025+/-0.002 for th e diamond detector and for the silicon diode, respectively. The a values we re found to be independent of particle type of two conventional beams (a 10 MV x-ray beam and a 21 MeV electron beam). So if Delta is determined for a radiotherapy beam; it can be used to correct relative dosimetry for other conventional radiotherapy beams. Moreover the diamond detector shows a cali bration factor which is independent of beam quality and particle type, so a n empirical dosimetric formalism is proposed here to obtain the reference d osimetry. This formalism is based on a dose-to-water calibration factor and on an empirical coefficient, that takes into account the reading dependenc e on the dose per pulse. (C) 2000 American Association of Physicists in Med icine. [S0094-2405(00)00711-2].