Abstract
Some parameters are included in the formulae for effective mass stopping power ratio in high-energy photon and electron dosimetry. In photon beams, the correction factor for transmission, through the cavity wall to the cavity, of secondary electrons arising in medium and the build-up rate in the wall of secondary electrons arising in the wall are estimated on the basis of two very simple models, an exponential attenuation and build-up model and a parallel plate model. In electron beams, the correction factor for transmission, through the wall to the cavity, of electrons is estimated from transmission probability of electrons. As an example, the values of those parameters are calculated for the JAM. substandard air ionisation chamber in water phantom. Although it seems to be open problem whether these models approximate correctly some complicated situations in practical dosimetry, the parameter values obtained in present work may be temporarily used till a better model would be known.
