Constancy checks of HDR well-type ionization chambers in the linac era: Potential use of a Sr source.

A methodology using aSr source, originally designed for constancy checks of parallel-plate ionization chambers, was proposed for constancy checks of HDR brachytherapy well-type ionization chamber (WTIC). The Sr source was positioned on the top of the WTIC, a reference reading value was established, and the constancy variation was calculated by the difference between each subsequent measurement and the reference value. This methodology was validated by calibrated Ir sources measurements and an acceptable tolerance limit for constancy variation of 1.

Monte Carlo studies on water and LiF cavity properties for dose-reporting quantities when using x-ray and brachytherapy sources.

Model-based dose calculation algorithms (MBDCAs) are the current tools to estimate dose in brachytherapy, which takes into account heterogeneous medium, therefore, departing from water-based formalism (TG-43). One aspect associated to MBCDA is the choice of dose specification medium since it offers two possibilities to report dose: (a) dose to medium in medium, D ; and (b) dose to water in medium, D . The discussion about the preferable quantity to be reported is underway.