A complete dosimetric characterization of two Sr-90-Y-90 dermatologic applicators

Abstract

A complete dosimetric characterization of two Amershan Sr-90-Y-90 dermatologic applicators is described in this present work. The dosimetric parameters analyzed are: percentage depth dose curve, radial dose distribution, non-uniformity and asymmetry. Both applicators are planar-circular having 22.57 and 9.0 mm diameters. In the range where the percentage depth dose goes from 100% down to 20%, the measured percentage depth dose and that obtained by the Monte Carlo simulation have shown maximum discrepancy of 5.3% for both applicators. The radial dose distribution has been measured at several depths using a GafChromic (R) EBT QD+ films and it was also calculated by simulation. The discrepancies found did not exceed 5.9% up to the depth of 1.8 mm, where the percentage depth dose drops to 40% of the maximum. The maximum non-uniformity and asymmetry are 1.7% and 5.3% for the first applicator and 22.7% and 25.9% for the second applicator, respectively. Both applicators meet the specification for the maximum non-uniformity established by the adopted protocol, whose limit is 30%. As for the asymmetry the limit is 20% and the second applicator exceeded it in about 5.9%. (C) 2010 Elsevier B.V. All rights reserved.