The PTB water calorimeter for the absolute determination of absorbed dose to water in Co-60 radiation

摘要

The quantity to be measured in dosimetry for radiation therapy is the absorbed dose to water, D-w. At the Physikalisch-Technische Bundesanstalt a water calorimeter is established as the primary standard for D-w in Co-60 radiation under reference conditions. The water calorimeter is capable of measuring the absorbed dose to water with a combined standard uncertainty of 0.20%. Some aspects of the design and operation of the water calorimeter are discussed. Detailed experimental and theoretical investigations for the different influence quantities affecting the calorimetric results are presented.