An algorithm to include the bremsstrahlung contamination in the determination of the absorbed dose in electron beams

None of the existing protocols or codes of practice for high-energy electron dosimetry take any account of the accelerator-generated bremsstrahlung always present in electron beams. This results in a systematic error in the derivation of the absorbed dose. The purpose of this study is to draw attention to this omission which affects the absorbed dose calibration. A method based on available experimental data is presented for dealing with this deficiency in electron dosimetry. A re-defined algorithm for absorbed dose derivation accounting for this bremsstrahlung component is proposed. The question of omission of the bremsstrahlung contamination is important in comparing ionization methods with other dosimetric methods such as calorimetry or the use of ferrous sulphate.