Comparisons of the Codes of Practice IAEA TRS 277 and TRS 398: High Energy Photons and Electron Beams

This work presents the calibration for: 6, 8, 10, 12, 14, 15 and 18 MeV electron beams, also to 6 and 15 MV photons beams. Beams that are generated by an accelerator Elekta Linac SL 18. The calibration is performed in terms of absorbed dose to water Dw. It is determined by two different protocols: the code of practice of the International Atomic Energy Agency (IAEA) TRS 277 for ionization chambers calibrated on air kerma NK, and the code of practice TRS 398 for ionization chambers calibrated on absorbed dose to water ND,W. Two independent dosimeters were used with two ionization chambers each one, respectively. The first one, a dosimeter PTW model UNIDOS with Markus type chamber (plane parallel) for electrons, and Farmer type chamber (cylindrical) for photons, both chambers calibrated in NK. The second dosimeter Scanditronix model DOSE 1 with plane parallel chamber (electrons) and cylindrical chamber (photons), both chambers calibrated in terms of ND,W. In the case of photon beams, the TPR was measured for 6 and 15 MV, also the profiles were determined in order to verify the flatness and symmetry of the beam: +/-3%. The quality for electrons beams were estimated by means of the Dmax, R80, R50 and Rp. The results obtained for the absorbed dose quotients DW,Q(dmax)277398{expression} are: Electrons, 0.976 DW,Q(dmax)277398{expression} 1.001; Photons: 1.001 DW,Q(dmax)277398{expression} 1.003.