Water calorimetry for radiation dosimetry

Calorimetry has a long history as a technique for establishing the absorbed dose, and graphite calorimetry has often been used to establish absorbed dose standards for use in radiation therapy. However, a conversion process is necessary to convert from dose to graphite to dose to water, which is the quantity of clinical interest. In order to more directly measure the dose to water, considerable effort has been devoted in the last fifteen years to the development of water calorimetry. This article reviews these developments and summarizes the present status of water calorimetry. Absorbed dose standards based on water calorimetry and with a relative standard uncertainty of 0.5 - 1% now seem achievable.