Comparison of dose distribution with simplified IMRT to different postoperative radiotherapy plans of rectal cancer / 中华放射肿瘤学杂志

ABSTRACT

Objective To evaluate the dose distribution of target volume and normal tissues with different treatment planning such as three dimensional conformal radiotherapy(3DCRT) ,simplified intensity modulated radiotherapy(sIMRT) ,and intensity modulated radiotherapy (IMRT) for patients with radically resected rectal cancer. Methods Ten male patients with stage Ⅱ and Ⅲ rectal cancer after radical resection (Dixon surgery) were enrolled in this study. 3-field or 5-field 3DCRT,slMRT and 5-field or 7-field IMRT plans were performed for each patient. The dose distributions of target volume and normal tissues,conformal index(CI) and heterogeneous index(HI) were analyzed using the dose-volume histogram(Dvit). The prescription dose was 50 Gy in 25 fractions. Results The CI for PTV of IMRT and sIMRT was superior to 3DCRT. Conversely,the HI for PTV of 3DCRT was superior to sIMRT and IMRT. sIMRT and IMRT can protect the organs at risk better than 3DCRT. The mean of total MU for 3DCRT3f,3DCRT5f, sIMRT, IMRT5f and IMRTT7f was 482±13,504±11,455±42,841±36 and 884±46, respectively. Conclusions Comparing with 3DCRT plans and IMRT plans, sIMRT plan was the optimal plan for clinical practice. All of the three radiotherapy techniques can protect the rectal stump and anal canal well with the prescription dose of 50 Gy.