Dosimetric verification of volumetric modulated arc therapy-based total marrow irradiation using Eclipse treatment planning: An anthropomorphic phantom study

Abstract

Introduction: The application of volumetric modulated arc therapy (VMAT) to treat total marrow irradiation (TMI) requires several arc fields, which is possible to present hot and cold spots between the arcs and the junctions between each planning target volume (PTV) subvolume. The objective of this study was to determine the dosimetric accuracy of volumetric modulated arc therapy-total marrow irradiation technique (VMAT-TMI). Material and methods: The treatment planning of Eclipse AAA algorithm version 13.6 with dose grid size of 2.5 mm was performed for VMAT technique. The PTV consisted of whole bone marrow from head to mid femur. Plans with 10 arcs were optimized for 6 MV photon beams with the dose prescription of 12 Gy in 6 fractions. This VMAT plan was evaluated by dosimetric verification using thermoluminescent dosimeter (TLD) to measure the radiation dose in the target of the anthropomorphic phantom. Gafchromic EBT3 films were also used to verify the planar dose at the overlapping regions and within some organs. The gamma criteria of 3%/3mm and 5%/5mm were applied for planar dose evaluation. All measurements were repeated 3 times. Results: The average %dose difference from TLD measurement in the H&N region was -1.39%, the chest region was 1.80%, the pelvis region was 2.75%, the H&N-chest junction was 2.95% and the chest-pelvis junction was -1.56%. The average %passing rate for gamma criteria of 3%/3 mm and 5%/5 mm from Gafchromics EBT3 films measurement in lungs were 89.1 ± 5.3% and 96.8 ± 1.3% and at the chest-pelvis junction were 84.2 ± 2.7% and 96.0 ± 0.2%, respectively. Conclusions: The results confirmed the accuracy of dosimetry for the gamma criteria of 5%/5mm. The VMAT-TMI plan could deliver radiation dose accurately and reliably with reasonable benchmark.