Application of a test package in an intercomparison of the photon dose calculation performance of treatment planning systems used in a clinical setting.

BACKGROUND AND PURPOSE Testing the performance of treatment planning systems by using the AAPM Task Group 23 test package is a useful approach, but has its limitations. To be able to include technical developments, such as the asymmetric collimator, it was decided to remeasure the AAPM data set on more modern radiotherapy equipment, to extend the test geometries, and to evaluate the use of the new package. MATERIALS AND METHODS A coherent set of beam data of 6, 10 and 18 MV photon beams was measured on two modern linear accelerators. These data served as input data in seven commercially available treatment planning systems, which were clinically in use in different radiotherapy departments. Next, a test package was measured which included a missing tissue geometry and fields with asymmetrical collimator setting, with and without a wedge. RESULTS The absolute dose prediction from the different treatment planning systems in which the measured beam data were entered, was compared for all test points with the results of direct measurements. The criteria of acceptability were exceeded by some systems in cases of irregular field geometry and missing tissue geometry. The majority of the systems had difficulties with accurate dose calculation for asymmetrically wedged fields. CONCLUSIONS The application of the new test package did not introduce insuperable difficulties and was highly appreciated by the participating centres. Most systems performed reasonably well for the majority of the beam geometries, with the exception of asymmetrically wedged beams. The extended test package is available for other users or user groups for the purpose of commissioning new treatment planning systems, or new releases of existing systems.