Physical Significance of the Röntgen for 22·5 MeV X Rays

Abstract

1. The results of a calorimetric determination of the energy flux of 22·5-MeV X rays relative to ionization measurements have been reported. 2. The energy flux has been related to the röntgen as measured according to a specified convention. 3. The absolute number of quanta/cm.2-r as a function of energy has been obtained from the experimental data and compared with calculated values. 4. A method of obtaining the energy absorbed in water in ergs per gm/r utilising this calorimetric energy flux determination together with existing dose distribution measurements has been outlined. A value has been calculated in terms of the ergs/gm.-r (M) and the ergs/gm-e.s.u./c.c. 5. An alternative convention for evaluation of the röntgen from depth-dose measurements is presented in the appendix.