宫颈癌术后4种放疗方式的剂量学比较

目的]分析宫颈癌术后前后对穿照射（FBRT）、四野盒式照射（FFRT）、三维适形（3DCRT）和调强（IMRT）4种放疗技术的剂量学特点。方法]收集8例宫颈癌术后放疗患者,分别设计FBRT、FFRT、3D-CRT和IMRT放疗计划;绘制出PTV的DVH示意图;比较各计划的靶区适形指数（CI）、均匀指数（HI）以及机器出束（MU）;计算小肠最大剂量D max、小肠和直肠受照40Gy以上体积（V40）,并寻找左右股骨颈D max和V40最优的计划方式。结果]FBRT、FFRT、3DCRT和IMRT的CI分别为0.32±0.09、0.35±0.08、0.61±0.09和0.83±0.14;HI分别为1.07±0.03、1.08±0.03、1.12±0.10和1.05±0.07;MU分别为5606±46、6451±49、6674±64、19321±141。PTV的DVH图以IMRT计划最优。小肠的D max和V40分别为5160±25、5139±24、5107±17、5078±23和76%±4%、57%±7%、34%±7%、29%±4%。直肠V40在IMRT中均值为45%,其余为100%;股骨颈D max在FFRT最大,为（5058±38）cGy;在IMRT最小,为（4762±31）cGy;股骨颈V40以3D-CRT最小,平均为7%±3%;FFRT最大,为19%±4%。结论]IMRT剂量分布最好,3D-CRT次之;在尚未具备条件开展IMRT的放疗单位开展3D-CRT也将使患者从中受益。

Dosimetric Analysis of Four Radiotherapy Techniques for Cervical Cancer Postoperation

Purpose] To compare and analyze the dose distribution of front-back field radiotherapy（FBRT）,four fields box of types in radiotherapy（FFRT）,three-dimensional conformal radiotherapy（3D-CRT） and intensity modulated radiotherapy（IMRT） for patients with cervical cancer postoperation. Methods] Four radiotherapy plannings were designed for eight cases with cervical cancer postoperation. The conformal index（CI）,homogeneity index（HI） and delivered MU were computed;a diagram of DVH for PTV were drawn;the mean value of V40for intestines,rectum and neck of femur,and the mean value of Dmax for intestines and neck of femur were calculated. Results]The CI in FBRT,FFTR,3D-CRT and IMRT were 0.32 ±0.09,0.35 ±0.08,0.61 ±0.09 and 0.83 ±0.14;the HI were 1.07 ±0.03,1.08 ±0.03,1.12 ±0.10 and 1.05 ±0.07;MU were 5606 ±46,6451 ±49,6674 ±64,19321 ±141,respectively. The intestines Dmax was 5160 ±25,5139 ±24,5107 ±17,5078±23;and the intestines V40was 76%±4%,57%±7%,34%±7%,29%±4%,respectively. The rectum V40was 45% in IMRT,but it was 100% in the others. The Dmax of neck of femur met the maximum in FFRT（5058±38 cGy） and the minimum in IMRT（4762±31cGy）. The V40of neck of femur met the minimum in 3D-CRT（7%±3%） and the maximum in FFRT（19%±4%）. Conclusion] IMRT is the best choice for patients with cervical cancer postoperation,but if the patient in a radiotherapy unit which is not capable of performing IMRT,who also can benefit from the 3D-CRT.