Dosimetric Comparison of Intensity-Modulated Radiotherapy and Volumetric Arc Therapy for Rectal Cancer

Abstract

OBJECTIVEThe aim of the present study is the dosimetric comparison of intensity-modulated radiation therapy andvolumetric arc therapy (VMAT) that are currently applied in the preoperative radiotherapy of locallyadvanced rectal cancer.METHODSTen patients with locally advanced rectal cancer were recontoured according to defined protocol oncomputed tomography simulation that was previously scanned. Dosimetric comparison was performedfor each patient with 7 and 9 fields intensity-modulated radiation therapy and VMAT. Compared dosimetric parameters were determined as doses of organs at risk, the total duration of treatment, targetcoverage, conformity index, homogeneity index, and the total monitor unit (MU).RESULTSAll plans provided comparable dosimetric parameters for target volumes. Arc plans demonstrated astatistically significant benefit with lower doses on V15 and Dmean of the small bowel than intensity-modulated radiation therapy. Arc plans were obviously superior relating to measured volumes of the wholebody, and plans with 7 field had the worst results. In addition, the reduction in total treatment time byapproximately 60% was achieved in arc plans.CONCLUSIONVMAT with short treatment duration and low MUs can be considered as providing a more comfortableand qualified treatment.