Poster - Thurs Eve-39: Full 3D dose calculation for total body irradiation: A comparison study between treatment planning systems in homogeneous and heterogeneous conditions

Medical Physics
M-C LavalléeLuc Beaulieu

Abstract

To perform full 3D heterogeneous dose calculations for total body irradiation (TBI) cases and compare different treatment planning softwares (TPS). A retrospective study was performed on 7 patients. Dose distributions obtained with Pinnacle(3) v.7.9u (Philips Medical Systems) were compared with the ones calculated using our actual TBI planning system Theraplan Plus (TPP) by MDS Nordion/Nucletron. Two different Pinnacle(3) models were studied: standard beam commissioning (std_Pinnacle(3) ) and TBI commissioning (TBI_Pinnacle(3) ). For the later case, commissioning was adapted for the special TBI conditions (extended SSD of 190cm, large field, acrylic beam spoiler, and out of field dose (OFD)). Significant differences are found between the TPP, std_Pinnacle(3) and TBI_Pinnacle(3) dose distributions. For the relative mid-line doses, differences up to 12% were observed. Systematic overestimations of 5% were found in patients extremities between TPP and TBI_Pinnacle(3) . Average dose underestimation of 3% was observed between std_Pinnacle(3) and TBI_Pinnacle(3) . Differences in patient extremities are attributed to the OFD contribution which is not correctly computed in TPP and std_Pinnacle(3) . Dose comparison outside the patient's...Continue Reading

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