RESPONSE OF THE ALANINE RADIATION DOSIMETER TO HIGH-ENERGY PHOTON AND ELECTRON-BEAMS

Alanine dosemeters have been exposed to beams of 4, 8 and 16 MVp X-rays and 6, 8, 10, 12, 14, 17 and 20 MeV electrons from linear electron accelerators used for radiation therapy. The dose levels used were 100 Gy or below. The theoretical energy dependence of the dosemeters have been calculated both for photons and electrons. After correction for the theoretical energy dependence, the response of the dosemeters had a coefficient of variation of 0.4% around the average value. The average response was within 1% of the response of the alanine dosemeters exposed to a 60Co gamma -ray source or a 137Cs gamma -ray source, both calibrated with ion chambers. The dosemeters have been used as an independent check of the output calibration of a linear accelerator before clinical use. The absorbed dose of the dosemeters was determined by comparison with those exposed to a 60Co gamma -ray source calibrated with Fricke dosimetry.