A dosimetric study of automated intensity-modulated radiotherapy planning for rectal cancer patients based on Pinnacle3 system / 中华放射医学与防护杂志

ABSTRACT

Objective To compare the dosimetric differences of the targets and the OARs in rectal cancer patients between Auto-planning and intensity-modulated radiotherapy (IMRT),and explore the advantages of Auto-planning (AP).Methods A total of 10 postoperative radiotherapy rectal cancer patients were selected,whose CT images were used to create AP plan and IMRT plan respectively using Pinnacle3 9.i0 treatment planning system.Through comparing the dose-volume histograms of the two plan types,the differences of the homogeneity index,conformity index and the doses to organs at risk (OARs) were analyzed.Results The AP plans were significantly better (t=-1.36,-3.03,0.37,P＜0.05) in terms of higher D Dmin and lower Dmax.But the differences in D2,Dg5,D98 were insignificant (P＞ 0.05).In the AP plan,the HI values of the target area were significantly reduced,and the CI values were significantly increased (t =1.24,0.10,P＜ 0.05).Significant superior results were found in V40,V50 of bladder,V30,V45,V50 of small intestine,V30,V40 of left and right femoral head (t=-3.21-1.02,P＜ 0.05).AP plans achieved insignificantly lower V30,V45 in bladder,V4o in small intestine and V45 in left and right femoral head than IMRT plan (P＞0.05).Conclusions Compare with IMRT plans,the AP plans for rectal cancer can achieve better homogeneity index,effectively reduce the maximum dose,increase the minimum dose,reduce hot and cold volumes in the target area.Meanwhile,AP plans can also protect the normal tissues better by reducing the dose to the OARs.