Addendum to brachytherapy dose-volume histogram commissioning with multiple planning systems

The process for validating dose-volume histogram data in brachytherapy software is presented as a supplement to a previously published article. Included is the DVH accuracy evaluation of the Best NOMOS treatment planning system called "Best TPS VolumePlan." As done previously in other software, a rectangular cuboid was contoured in the treatment planning system. A single radioactive 125I source was positioned coplanar and concentric with one end. Calculations were performed to estimate dose deposition in partial volumes of the cuboid structure, using the brachytherapy dosimetry formalism defined in AAPM Task Group 43. Hand-calculated, dose-volume results were compared to TPS-generated, point-source-approximated dose-volume histogram data to establish acceptance. The required QA for commissioning was satisfied for the DVH as conducted previously for other software, using the criterion that the DVH %VolTPS "actual variance" calculations should differ by no more than 5% at any specific radial distance with respect to %VolTG-43, and the "average variance" DVH %VolTPS calculations should differ by no more than 2% over all radial distances with respect to %VolTG-43. The average disagreement observed between hand calculations and treatment planning system DVH was less than 0.5% on average for this treatment planning system and less than 1.1% maximally for 1 ≤ r ≤ 5 cm.