Absorbed dose determination in water. II

The use of new values of physical parameters as recommended by international organizations has consequences in radiotherapy, e.g. in the determination of absorbed doses in water based on ionometric measurements. A procedure is proposed for the determination of the conversion factor Kw,e from kerma in air to absorbed dose in water, and of the conversion factor Cw,e from exposure measured to dose absorbed in water, this for ionization chambers and high-energy electron beams. The conversion factors depend not only on the radiation quality and measurement depth in the phantom but also on the dimensions and composition of the chamber and of the cup used in the calibrations. Numerical values are given for two conventional kinds of ionization chambers. (author). 3 tabs., 9 refs