SU‐E‐T‐615: SmartArc‐Based Volumetric Modulated Arc Therapy for Endometrial Cancer: A Dosimetric Comparison with Helical Tomotherapy and Intensity‐Modulated Radiation Therapy

Abstract

Purpose: To investigate the feasibility of volumetric modulated arc therapy with Smart Arc (VMAT‐S) for endometrial cancer to achieve equivalent plan quality with higher delivery efficiency, against intensity‐modulated radiotherapy (IMRT) and helical tomotherapy (HT). Methods: Nine patients with endometrial cancer were retrospectively studied. Three plans were generated with VMAT‐S, IMRT and HT for each patient. The dose distribution of planning target volume (PTV), organs at risk (OARs) and normal tissue were compared. The monitor units (MUs) and treatment delivery time were also evaluated. Results: The average homogeneity index was 1.06, 1.10 and 1.07 for VMAT‐S, IMRT and HT plans. The V40 of rectum, bladder and pelvis bone decreased 9.0%, 3.0%, and 3.0% in VMAT‐S compared with IMRT, respectively. The target coverage and OARs sparing were comparable between VMAT‐S and HT. The average MU was 823, 1105 and 8403 for VMAT‐S, IMRT and HT. The average delivery time was 2.6 minutes, 8.6 minutes, and 9.5 minutes. Conclusion: VMAT‐S provided comparable plan quality with significantly shorter delivery time and less MUs compared with IMRT and HT for endometrial cancer. In addition, more homogeneous PTV coverage and superior OARs sparing in the medium to high dose region were observed in VMAT‐S over IMRT. Ruijie Yang was funded by the grant project: National Natural Science Foundation of China (No. 81071237). Junjie Wang, Shouping Xu and Hua Li have no competing interest.