宫颈癌九野均分与角度优化IMRT计划剂量学比较

目的 比较宫颈癌术后患者9个野均分和角度优化的IMRT计划靶区和OAR剂量学参数差异。方法 对 12例宫颈癌术后患者CT图像分别设计9个野均分IMRT计划和利用角度优化产生9个野IMRT计划。评估靶区及OAR剂量分布并配对t检验差异。结果 射野角度优化与均分IMRT计划相比,PTV的 V_95%、V_105%、V_110%分别为99.31%∶99.42%(P=0.020)、60.54%∶47.92%(P=0.013)、7.14%∶0.37%(P=0.000);D_max、D_mean分别为56.62 Gy∶55.47 Gy (P=0.000)、53.29 Gy∶52.72 Gy (P=0.000);CI、HI分别为0.85∶0.89(P=0.000)、0.10∶0.13(P=0.000);膀胱 V₄₀增加约4.7%(P=0.013),直肠 D₄₀增加约0.5 Gy (P=0.004),小肠 V₄₀升高约0.6%(P=0.015)、D_max增加1.4 Gy (P=0.000),骨髓 D_mean均升高约1.3 Gy (P=0.000),马尾神经 D_{0.1 cm³}增加2.0 Gy (P=0.000)。结论 9个野均分IMRT计划质量明显优于通过射野角度优化的IMRT计划。

Dosimetric comparison of Cervix uteri irradiation with 9 equal spaced fields IMRT and beam angle optimized IMRT

Objective To study the dosimetry characteristics of 9 equal spaced fields and 9 fields with beam angle optimization (BAO) process for cervix uteri. Methods 12 cervix uteri cancer patients CT Images were transferred into Eclipse planning system. Each patient, the 9 equal spaced fields and 9 fields by BAO process were IMRT plan designed with the same CT image. Make a evaluation of dose distribution for target volume and OARs, and paired t test for them. Results Comparing to 9 equal spaced fields IMRT plan, the quality of 9 fields IMRT plan with BAO process the the PTV V_95% was 99.31% vs 99.42%,P=0.020, at the same time V_105%,V_110%,D_max,D_mean got 60.54% vs 47.92%,P=0.013;7.14% vs 0.37%,P=0.000;56.62 Gy vs 55.47 Gy,P=0.000;53.29 Gy vs 52.72 Gy,P=0.000, the CI and HI was 0.85 vs 0.89,P=0.000;0.10 vs 0.13,P=0.000.For organs at risk, bladder V₄₀ was increased by 4.7%(P=0.013);the D₄₀ of rectum was 0.5 Gy higher (P=0.004);the small bowel′s DVH showed that V₄₀ and D_max increased by 0.6%(P=0.015) and 1.4 Gy (P=0.000), D_mean of bone marrow were raised separately by 1.3 Gy (P=0.000),the spinal cord′s dose D_{0.1 cm³} was also increased by 2.0 Gy (P=0.000). Conclusion The quality of 9 equal spaced fields IMRT plan will be better than those achieved by BAO process optimized plans.