Source of Support: None, Conflict of Interest: None
Electron beam dosimetry with a cylindrical ion chamber has had associated with it an uncertainty about the effective point of measurement and difficulty in accurately measuring surface dose. Using two mathematical functions and data taken with a cylindrical ion chamber in air and a phantom, one can determine the effective point of measurement and surface dose for clinical electron beams. We found the effective point of measurement to be inversely related to beam energy. The method detailed here is simple, easy and accurate for the estimation of surface dose in a clinical setting.