Brachytherapy dose‐volume histogram commissioning with multiple planning systems

Abstract

The first quality assurance process for validating dose‐volume histogram data involving brachytherapy procedures in radiation therapy is presented. The process is demonstrated using both low dose‐rate and high dose‐rate radionuclide sources. A rectangular cuboid was contoured in five commercially available brachytherapy treatment planning systems. A single radioactive source commissioned for QA testing was positioned coplanar and concentric with one end. Using the brachytherapy dosimetry formalism defined in the AAPM Task Group 43 report series, calculations were performed to estimate dose deposition in partial volumes of the cuboid structure. The point‐source approximation was used for a 125I source and the line‐source approximation was used for a 192Ir source in simulated permanent and temporary implants, respectively. Hand‐calculated, dose‐volume results were compared to TPS‐generated, dose‐volume histogram (DVH) data to ascertain acceptance. The average disagreement observed between hand calculations and the treatment planning system DVH was less than 1% for the five treatment planning systems and less than 5% for 1 cm≤r≤5 cm. A reproducible method for verifying the accuracy of volumetric statistics from a radiation therapy TPS can be employed. The process satisfies QA requirements for TPS commissioning, upgrading, and annual testing. We suggest that investigations be performed if the DVHnormal%VolTPS “actual variance” calculations differ by more than 5% at any specific radial distance with respect to normal%VolTG−43, or if the “average variance” DVH DVHnormal%VolTPS calculations differ by more than 2% over all radial distances with respect to normal%VolTG−43.PACS numbers: 87.10.+e, 87.55.‐x, 87.53.Jw, 07.05.Tp

Comprehensive methodology for commissioning modern 3D-image-based treatment planning systems for high dose rate gynaecological brachytherapy: A review

“…Validates DVH generation accuracy and shows the overall accuracy of contouring, volume calculation, and DVH computation [3][4][5]11,13,14,17,18,32,56,57,59]. TL: 2% [3,56] if the validation is carried out for one radial distance of the Gossman method to 5% for several radial distances [56].…”

“…-Does the DVH generation algorithm correctly compute the DVH [7,17]? -What factors are critical in generating an accurate DVH [5,17,18,56]? -Does the TPS accurately compute DVH-based parameters according to the vendor's manual [14,18]?…”

AAPM recommendations on medical physics practices for ocular plaque brachytherapy: Report of task group 221

“…The AAPM TG‐53 report remains a useful tool for commissioning brachytherapy TPSs . Non‐dosimetric tests include determining processes for entering source locations, verifying the accuracy of source position display, testing of data input, and validating tools such as the dose‐volume‐histogram (DVH) . For dosimetric tests, TG‐53 notes that commissioning within the TG‐43 paradigm can be relatively straightforward compared to external beam, due to the simplistic calculation algorithm, standardized sources, use of dosimetric parameters from the literature, and assumption of a homogeneous medium.…”

Sensitivity of dose‐volume indices to computation settings in high‐dose‐rate prostate brachytherapy treatment plan evaluation

“…Moreover, a comparison of plans between different TPSs is difficult if the DV computation settings are different. The differences in DV indices between phantom‐based values and TPSs, as well as between different commercial TPSs have been investigated before. However, the effects of different settings in the computation of DV indices on the DV‐index values of actual clinical treatment plans were not analyzed in such a manner.…”