子宫颈癌术后4种放疗计划的剂量学对比研究

Dosimetric analysis and comparsion of cervical cancer after operated for four kinds of radiotherapy

目的比较宫颈癌术后前后对穿照射,四野盒式照射,三维适形放疗和调强技术的剂量分布方法收集8例宫颈癌术后放疗患者,勾画PTV,小肠,直肠和左右股骨颈。分别设计前后对穿照射,四野盒式照射,三维适形放疗和调强放疗计划;比较各种计划的靶区适形指数(comformal index,CI)和均匀指数(homogeneity indes,HI),小肠,股骨颈与直肠最大剂量和受照40Gy以上的体积百分比(V40)。结果前后对穿照射,四野盒式照射,三维适形放疗以及调强技术靶区适形指数(CI)平均值分别为:0.32±0.31,0.35±0.27,0.61±0.33和0.83±0.42。均匀指数(HI)平均值分别:1.07±0.12,1.08±0.07,1.12±0.32和1.05±0.21。小肠最大受照剂量和V40平均值分别为5158±180,5145±153,5102±209,5078±214;78±13%,57±21%,34±24%,29±11%。直肠最大剂量各类计划间相差最大为140cGy,V40在IMRT计划中均值为45%,其余三计划全为100%。左右股骨颈最大受照剂量在四野盒式照射中最大,为5058cGy;在IMRT最小,为4762cGy;V40以三维适形放疗计划最小,平均为6%;四野盒式照射最大,平均为19%。结论从各指标上看,调强计划剂量分布最好,三维适形放疗计划次之;对与尚未具备条件开展调强的放疗单位开展三维适形放疗也将使患者受益。

Objective To compare and analyze the difference of dose distribution for front-back field radiotherapy（FBFRT）,four fields box of types in radiotherapy（FFBRT）,three dimensional conformal radiotherapy（3 dCRT） and intensity modulated radiotherapy（IMRT） in the cervical cancer after operated.Methods For eight cases of cervical cancer after operated,drawing the contours of PTV,intestine,rectum,the left femoral head and right femoral head,compare the comformal index（CI）,homogeneity index（HI）,the max dose and the V40 dose of intestine,rectum,the left femoral head and right femoral head in FBFRT,FFBRT,3 dCRT and IMRT.Results The CI of FBFRT,FFBRT,3 dCRT and IMRT is：0.32±0.31,0.35±0.27,0.61±0.33 and 0.83±0.42.The HI is：1.07±0.12,1.08±0.07,1.12±0.32 and 1.05±0.21.The max dose of intestine is：5158±180,5145±153,5102±209,5078±214.The V40 of intestine is 78±13%,57±21%,34±24%,29±11%.The difference of the max dose of rectum is 140 cGy in the four kinds of radiotherapy,the mean-V40 of the rectum is 45% in the IMRT,100% in others.The max dose of the left femoral head and right femoral head has the maximum in FFBRT（5058 cGy）,the minimum in IMRT（4762 cGy）,the V40 in the 3 dCRT is the minimum（6%）,the maximum in FFBRT（19%）.Conclusion From the dose distribution,the IMRT is the best choice for the patients of cervical cancer after operated,and the 3 dCRT take the second place.The radiotherapy centre which can not implement the technique of IMRT developing the 3 dCRT will also benefit the patients.