Poster - Thur Eve - 74: A set of tests designed for electron dose calculation algorithm verification during a...

A set of tests were designed to verify an electron algorithm effectively and quickly during a treatment planning system upgrade. Based on TG-53 report's suggestion and the assumption that the algorithm is well commissioned before the upgrade, the tests spot-check the output factors, depth doses, off-axis doses and treatment field sizes. The field sizes of 4×4, 6×6, 10×10, 15×15, 20×20 and 25×25 are to be tested. Four test plans are created for each field size, i.e., for open field, for extended SSD, for shaped field, and for bolus field. Fixed MU setting is recommended to avoid a possible plan normalization issue. The parameters to be recorded and compared include doses at d_max , R₅₀ and R_p along central axis, which contain output and depth dose information, doses at four off-axis points in d_max plane, which contain off-axis dose and beam symmetry information, and FWHMs at d_max . For the plans other than open field only doses at d_max are checked. The tests were performed successfully during a planning system upgrade. The whole test can be completed in approximately 12 hours if the workload is distributed into multiple task carriers. It was found that most of the data agree very well between the old and the new version of the algorithm while some of the R_p or R₅₀ doses deviated more than other data, which prompted a depth dose check. PDD comparisons were performed for the involved fields and it was found there were less than 0.5 mm PDD shifts occurred.