Evaluation of volumetric modulated arc therapy planning for rectal cancer based on Auto-Planning / 中华放射肿瘤学杂志

ABSTRACT

Objective To determine whether Auto-Planning-based volumetric modulated radiotherapy(Auto-VMAT)planning can improve planning efficiency without compromising plan quality compared with current manual trial-and-error-based volumetric modulated arc therapy(Manual-VMAT) planning for patients with rectal cancer. Methods Ten patients with stage Ⅱ-Ⅲ rectal cancer who underwent Dixon surgery were enrolled as subjects. The Pinnacle 9.10 planning system was used to design Manual-VMAT and Auto-VMAT plans. Dose distribution,homogeneity index(HI),conformity index(CI), D meanvalues of different organs at risk or dose-volume histogram of regions of interest,total planning time, and manual planning time were compared between the two plans. The differences were analyzed by paired t test. Results Dosimetric prescriptions were achieved in both plans. There were no significant differences in HI or CI between the Auto-VMAT plans and the Manual-VMAT plans(0.058 vs. 0.058, P=0.972;0.921 vs. 0.940,P=0.115). Compared with the Manual-VMAT plans,the V 40,D mean,and D 50%of the bladder were significantly reduced by 25.6%, 11.5%, and 8.9%, respectively, in the Auto-VMAT plans(P=0.004,0.016,0.001);the V 40,D mean,and D 50%of the small intestine were also significantly reduced by 12.1%,5.4%,and 6.8%,respectively,in the Auto-VMAT plans(P=0.023,0.001,0.001);the V 30, D mean,and D 50%of the left and right femoral heads were slightly reduced in the Auto-VMAT plans. The Auto-VMAT plans had significantly longer total planning time but significantly shorter manual planning time than the Manual-VMAT plans(50.38 vs. 36.81 min, P= 0.000;4.47 vs. 16.94 min, P= 0.000). Conclusions Compared with the Manual-VMAT plans, the Auto-VMAT plans have substantially shorter manual planning time and improved planning efficiency.