Dosimetry formalism and calibration procedure for electronic brachytherapy sources in terms of absorbed dose to water.

The LNE-LNHB has developed a methodology to standardize electronic brachytherapy sources in terms of absorbed dose to water. It is based on the measurement of the air-kerma rate at a given distance from the source and the Monte Carlo calculation of a conversion factor. This factor converts the air-kerma in measurement conditions into absorbed dose to water at a 1 cm reference depth in a water phantom. As a first application, the method was used to calibrate a Zeiss INTRABEAM system equipped with its 4 cm diameter spherical applicator. The absorbed-dose rate value obtained in the current study was found significantly higher than that provided by the manufacturer in line with the observations already reported by a few other teams.