Abstract

The aim of the study was determination of dose distribution below a commercially available tungsten eye-shield for 9, 12 and 16 MeV electron beams. Dose measurements were performed with EPR dosimetry using alanine film dosimeters. The dosimeters were placed on the beam axis at chosen depths below the eye-shield.

At 5-9 mm depth the measured dose was within 6-14% of the dose at dmax in an open field, what gives a necessary protection inside the eye lens. The local maximum of dose distribution of 35-40% of the dose at dmax was found at the depth of about 1.5, 3.5 and 6.5 cm for energies 9, 12 and 16 MeV, respectively. These maxima potentially could cause a radiation risk to the retina and optic nerve fibers, however, the total doses applied during radiotherapy (the doses at the local maxima) did not exceed the accepted dose limits for those critical organs.