应用4DCT技术确定食管癌放疗靶区及其剂量学研究

目的 比较胸中下段食管癌3D、4D放疗计划的靶区大小、靶区位移及相关剂量学差异,评估4D计划的临床价值。方法 2012年内 19例胸中下段食管癌患者分别在同次CT模拟定位时序贯行3D、4D扫描,模拟勾画二者靶区及OAR。设计3D计划和4D计划,比较3D计划与4D计划靶体积、中心点位移及OAR剂量学差异。在各项参数相同下将3D计划平移至4DCT形成3DC计划,并比较3DC计划与3D计划靶区剂量学差异。采用配对t检验或Wilcoxon符号秩检验两套计划差异。结果 全组4DCT的PTV大于3DCT (195.19 cm³∶175.67 cm³,P=0.001)。10例胸中段食管癌中心点位移仅左右方向不同(位移为0.25 cm,P=0.014)。9例胸下段食管癌中心点位移3个方向差异无统计学意义(P=0.722、0.307、0.208)。19例胸中下段食管癌3DC计划中 V₁₀₀、V₉₅、V₉₀均低于3D计划(88.62%∶95.69%,P=0.000;95.17%∶99.79%,P=0.001;97.19%∶99.99%,P=0.001)。全组4D计划两肺 V₅、V₂₀及心脏 D_mean均高于3D计划(39.49%∶37.44%,P=0.016;19.93%∶18.87%,P=0.018及2607.74 cGy∶2389.16 cGy,P=0.004),但均未超出剂量限制范围。结论 4DCT定位技术能准确确定胸中下段食管癌靶区个体化外扩边界,4D计划因靶区增大虽使肺受量增加但在剂量限制范围内,4D计划使心脏受量增加应引起注意。

Target volume definition using 4DCT and dosimetric evaluation for esophageal cancer

Objective To study the PTV by ng 4DCT and compare target, target displacement and dose distribution of 3D and 4D planning for thoracic middle or lower esophageal cancer, evaluate the clinical value of 4DCT in esophageal cancer radiotherapy. Methods From Jan to Dec 2012patients with primary esophageal cancer underwent 3DCT simulation scans first, then followed by 4DCT simulation scan. PTV and OARs were sketched in the ordinary 3DCT and 4DCT respectively. And designing two sets of radiotherapy plan for each patient:3D and 4D plan. We compare PTV, PTV displacement and OARs dosimetry′s differences in the 3D plan and 4D plan. Using the paired t-test or Wilcoxon sign-rank test to compare the difference between the two sets of plans. Results The volume of PTV_4D was larger than the PTV_3D (195.19 cm³ vs.175.67 cm³,P=0.001) in all patients. The center displacement had only significantly difference (displacement was 0.25 cm,P=0.014) in left-right direction for 10 patients of thoracic middle esophageal cancer. The center displacement had no significantly different in the three direction for 9 patients of thoracic under esophageal cancer (P=0.722,0.307,0.208). The dose target area of V₁₀₀, V₉₅ and V₉₀ in Plan-3DC were significantly than those in Plan-3D for 19 patients of thoracic middle-lower esophageal cancer (88.62% vs. 95.69%,P=0.000;95.17% vs. 99.79%,P=0.001;97.19% vs. 99.99%,P=0.001). In 4D plan the lung V₅, V₂₀ and D_mean of heart were higher than that in 3D plan for all patients (39.49% vs. 37.44%,P=0.016;19.93% vs. 18.87%,P=0.018 and 2607.74 cGy vs. 2389.16 cGy,P=0.004). Conclusions 4DCT positioning technology can accuracy determine individualized expanding boundary by target area of radiotherapy for thoracic middle or lower esophageal cancer. The enlarging target volume increase the dose of radiotherapy for lung, and in the dose range in the 4D plan, but the increased dose of heart should be noted.