Full characterization of the 125I IBt Bebig I25.S16 brachytherapy source and sensitivity study of the absorbed dose to water due to the seed dimensional variations

125I brachytherapy sources have a complex geometry with very small dimensions. Those specificities induce problems of reproducibility in the manufacturing process. The consequence of this lack of reproducibility is a variation of the flux of the photonic emission from one seed to another. Consequently, it was observed that the spatial distribution of the absorbed dose to water is very dependent on the seed characteristics (geometry and components of the internal and wrapping materials). The purpose of this study was to quantify the sensitivity of the distribution of the absorbed dose to water due to the multi-element constitution and dimensional variations of the seeds.