Source of Support: None, Conflict of Interest: None
Several protocols had been proposed for calibrating high energy beam therapy machines. They require an accurate determination of physical parameters to convert depth ionisation to absorbed dose. The direct calculation of these parameters is quite a difficult task and time consuming. Alternatively, the dosimetric protocols had proposed tabulated values for these parameters. However, published data always don't agree with the values encountered in routine calibration. In this paper, semi-analytical expressions of the most important parameters, used in high energy electron beam calibration, have been derived. These expressions yield an alternative procedure for computing the various parameters instead of obtaining them from the published tables by tedious interpolations.