Abstract

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Title:: Dosimetric comparison of VMAT and IMRT in postoperative radiotherapy for rectal cancer patients

Author(s):: QIN Dandan1; HAN Jihua1; DAI Tingting1; YANG Chun2; 1. Department of Radiotherapy, Huaian First Peoples Hospital, Huaian 223300, China 2. Department of Radiotherapy, Huaian Second Peoples Hospital, Huaian 223002, China

Keywords:: rectal cancer radiotherapy volumetric modulated arc therapy intensity-modulated radiotherapy dosimetry

Abstract:: Abstract: Objective To compare and analyze dosimetric differences of volumetric modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) in postoperative radiotherapy for patients with rectal cancer. Methods Thirty-seven patients with rectal cancer were enrolled. CT simulation was performed, followed by target volume and organs-at-risk delineation. IMRT and VMAT plans were generated on the same CT image using the treatment planning system, with a prescribed dose of 50 Gy in 25 factions and the identical dose constraints. The two plans were compared in terms of mean target dose, conformity index (CI), homogeneity index (HI), doses to organs-at-risk, monitor unit, and delivery time. Results Both treatment plans met clinical dose criteria. Compared with IMRT, VMAT achieved a slightly higher mean target dose and superior HI and CI, with statistically significant differences (P<0.05). No significant inter-plan differences were observed in the doses delivered to important organs-at-risk (bladder and femoral heads) (P>0.05). In addition, VMAT required fewer monitor units and shorter delivery time relative to IMRT (P<0.05). Conclusion Both VMAT and IMRT satisfies the clinical requirements for postoperative radiotherapy of patients with rectal cancer. VMAT can significantly reduce monitor unit and shorten delivery time.