Dosimetric comparison between automated and manual volumetric modulated arc therapy planning for postoperative cervical cancer

Abstract

Objective To compare dosimetric parameters between automated and manual volumetric modulated arc therapy(VMAT) plans in the treatment of postoperative cervical cancer patients, and to investigatethe feasibility and dosimetric advantage of the automated VMAT planning. Methods Automated and manual VMAT plans were generated with Pinnacle3 treatment planning system(TPS)for twenty-three postoperative cervical cancer patients, including eight patients in stage ⅡA and fifteen in stage ⅡB, respectively. The differences in Dmean, D95, conformity index (CI) and homogeneity index (HI) of target, as well as dose volume histogram (DVH) of organs at risk (OAR), planning time, average optimization time and monitor unit (MU) were compared between automated and manual VMAT plans. Results The average Dmean, CI and HI of automated VMAT plans were better than those of manual VMAT plans (t=4.65-14.92, P 0.05). The automated VMAT plans achieved better average dosimetric parameters on OARs compared with the manual VMAT plans (t=3.30-14.42, P<0.05). Automated VMAT plans had a significantly shorter planning time (72 min, t=3.85, P<0.05) and interruption frequency (twice, t=5.41, P<0.05) than manual VMAT plans. However, automated VMAT plans had a higher average MU than manual VMAT plans with an average MU of 819±53 and 638±41 for automated and manual VMAT plans, respectively. Conclusions It is feasible to generate automated VMAT plans with Pinnacle3 TPS for postoperative cervical cancer patients. The automated VMAT plans increase the plan quality and reduce the optimization time compare with manual VMAT plans. Automated technique also eliminates the influence of human factors on the plan quality. Key words: Automated VMAT plan; Manual VMAT plan; Postoperative cervical cancer; Dosimetry