SU‐E‐T‐744: The Study of Total Marrow Irradiation Based On Rotational Intensity‐Modulated Techniques

Abstract

Purpose:This study is to compare the dosimetric characteristics and efficiency of RapidArc and Tomotherapy in total marrow irradiation (TMI) for hematologic malignancies in order to get the reference data for the choice of clinical application.Methods:Eight patient plans were retrospectively designed and analyzed for RapidArc and Tomotherapy. Total bone morrow was contoured as clinical target volume excluding the cubitus and hand part, then plus a 3.0mm margin as planning target volume. The prescription was 12Gy in 10 fractions. ArcCHECK system was used for dose verification, and the safety and accuracy of clinical delivery would be evaluated.Results:It showed that the two techniques could well achieve the target coverage. The conformity indexes of RapidArc and Tomotherapy were 0.54±0.05 vs 0.52±0.07 (p=0.45), but Tomotherapy plans have a visible advantage over RapidArc plans in the dose uniformity of target. The homogeneity indexes were 0.19±0.02 vs 0.13±0.02 (p=0.00). Tomotherapy plans showed better in sparing of the critical organs apart from the whole brain, oral, parotid gland, the small intestine, rectum, and the maximum dose of lens of Tomotherapy plans was reduced by 41% comparing to RapidArc plans. The MUs and treatment delivery time of RapidArc and Tomotherapy were 2608MU/560s vs 12842MU/891s. The γ‐analysis passing rates for head‐neck, chest‐abdomen, pelvic were 98.9±1.9%, 98.4±1.8%, 97.4±2.1% for RapidArc and 94.3±1.5%, 96.5±1.2%, 94.1±1.9% for Tomotherapy plans.Conclusion:The two methods using RapidArc and Tomotherapy could achieve the acceptable dose of TMI, and the delivery efficiency of RapidArc was better than Tomotherapy. Two kinds of techniques are promising and can solve the clinic implementation of TMI.This work was supported in part by the grant from Chinese Natural Science Foundation (Grant No. 11105225).