Fu Yuchuan, Deng Min, Zhou Xiaojuan, Lin Qiang, Du Bin, Tian Xue, Xu Yong, Wang Jin, Lu You, Gong Youling
Division of Radiation Physics, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, P.R. China.
Department of Thoracic Oncology, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, P.R. China.
Med Dosim. 2017;42(1):47-52. doi: 10.1016/j.meddos.2016.11.002. Epub 2017 Jan 23.
To evaluate the lung sparing in intensity-modulated radiation therapy (IMRT) for patients with upper thoracic esophageal tumors extending inferiorly to the thorax by different beam arrangement. Overall, 15 patient cases with cancer of upper thoracic esophagus were selected for a retrospective treatment-planning study. Intensity-modulated radiation therapy plans using 4, 5, and 7 beams (4B, 5B, and 7B) were developed for each patient by direct machine parameter optimization (DMPO). All plans were evaluated with respect to dose volumes to irradiated targets and normal structures, with statistical comparisons made between 4B with 5B and 7B intensity-modulated radiation therapy plans. Differences among plans were evaluated using a two-tailed Friedman test at a statistical significance of p < 0.05. The maximum dose, average dose, and the conformity index (CI) of planning target volume 1 (PTV1) were similar for 3 plans for each case. No significant difference of coverage for planning target volume 1 and maximum dose for spinal cords were observed among 3 plans in present study (p > 0.05). The average V, V, V, mean lung dose, and generalized equivalent uniform dose (gEUD) for the total lung were significantly lower in 4B-plans than those data in 5B-plans and 7B-plans (p < 0.01). Although the average V for the total lung were significantly higher in 4B-plans than those in 5B-plans and 7B-plans (p < 0.05). In addition, when comparing with the 4B-plans, the conformity/heterogeneity index of the 5B- and 7B-plans were significantly superior (p < 0.05). The 4B-intensity-modulated radiation therapy plan has advantage to address the specialized problem of lung sparing to low- and intermediate-dose exposure in the thorax when dealing with relative long tumors extended inferiorly to the thoracic esophagus for upper esophageal carcinoma with the cost for less conformity. Studies are needed to compare the superiority of volumetric modulated arc therapy with intensity-modulated radiation therapy technique.
通过不同的射束排列方式评估调强放射治疗（IMRT）对胸段上段食管癌向下延伸至胸部患者的肺保护作用。总体而言，选取了15例胸段上段食管癌患者进行回顾性治疗计划研究。通过直接机器参数优化（DMPO）为每位患者制定了使用4野、5野和7野（4B、5B和7B）的调强放射治疗计划。所有计划均根据照射靶区和正常结构的剂量体积进行评估，并对4B与5B及7B调强放射治疗计划进行统计学比较。使用双侧Friedman检验评估计划间差异，统计学显著性水平为p < 0.05。每个病例的3种计划中，计划靶区1（PTV1）的最大剂量、平均剂量和适形指数（CI）相似。本研究中3种计划在计划靶区1的覆盖范围和脊髓最大剂量方面未观察到显著差异（p > 0.05）。4B计划中全肺的平均V、V、V、平均肺剂量和广义等效均匀剂量（gEUD）显著低于5B计划和7B计划中的数据（p < 0.01）。尽管4B计划中全肺的平均V显著高于5B计划和7B计划（p < 0.05）。此外，与4B计划相比，5B和7B计划的适形/不均匀指数显著更优（p < 0.05）。4B调强放射治疗计划在处理胸段上段食管癌相对较长且向下延伸至胸段食管的肿瘤时，在低至中等剂量照射下对胸部进行肺保护这一特殊问题方面具有优势，但代价是适形性较差。需要开展研究比较容积调强弧形治疗与调强放射治疗技术的优势。
