Development of a secondary standard for the absorbed dose to water based on the alanine EPR dosimetry system

The primary measurand in the dosimetry for radiation therapy is the absorbed dose to water, D-W. An alanine/EPR based secondary standard for D-W for high-energy photon and electron radiation is presently under construction at the Physikalisch-Technische Bundesanstalt. A technique of transfer dosimetry that makes it possible to reduce the reproducibility to a level below 0.5% in the 5-50Gy range is presented. It takes advantage of a reference sample. Results of investigations of some effects, such as environmental humidity, are presented. (c) 2004 Elsevier Ltd. All rights reserved.