Trager Michael, Landers Angelia, Yu Yan, Shi Wenyin, Liu Haisong
Department of Radiation Oncology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, United States.
Front Oncol. 2020 Apr 3;10:346. doi: 10.3389/fonc.2020.00346. eCollection 2020.
The Elements Spine Stereotactic Radiosurgery treatment planning system uses automated volumetric modulated arc radiotherapy that can provide a highly conformal dose distribution to targets, which can provide superior sparing of the spinal cord. This study compares the dosimetric quality of Elements plans with the clinical plans of 20 spine stereotactic radiosurgery/stereotactic body radiation therapy (SRS/SBRT) patients treated at our institution. Twenty spine SRS/SBRT patients who were clinically treated at our institution were replanned using the automated Elements planning workflow with prespecified templates. Elements automatically evaluates the size and shape of the target to determine if splitting the PTV into simplistic subvolumes, each treated by their own arc(s), would increase conformity and spinal cord sparing. The conformity index, gradient index, PTV , and maximum and mean cord dose were evaluated for the Elements and clinical plans. Treatment delivery efficiency was also analyzed by comparing the total number of monitor units and the modulation factor. Wilcoxon rank-sum tests were performed on the statistics. Elements split the PTV for 50% of cases, requiring four or six arcs. Overall, Elements plans were found to be superior to clinical plans in conformity index, gradient index, and maximum cord dose. The PTV and cord mean dose for the Elements plans trended higher and lower, respectively. The numbers of monitor units and modulation factor were also higher for Elements plans, although the differences were not significant. Automated Elements plans achieved superior conformity and cord dose sparing compared to clinical plans and PTV splitting successfully improved spinal cord sparing.
元素脊柱立体定向放射治疗计划系统采用自动容积调强弧形放疗，可为靶区提供高度适形的剂量分布，从而能更好地保护脊髓。本研究比较了元素计划与在我们机构接受治疗的20例脊柱立体定向放射治疗/立体定向体部放射治疗（SRS/SBRT）患者临床计划的剂量学质量。对在我们机构接受临床治疗的20例脊柱SRS/SBRT患者，使用具有预先指定模板的自动元素计划工作流程重新进行计划。元素系统会自动评估靶区的大小和形状，以确定将计划靶体积（PTV）分割成简单的子体积（每个子体积由各自的弧形束治疗）是否会提高适形度并更好地保护脊髓。对元素计划和临床计划评估了适形指数、梯度指数、PTV、脊髓最大剂量和平均剂量。还通过比较监测单位总数和调强因子分析了治疗实施效率。对这些统计数据进行了Wilcoxon秩和检验。元素系统在50%的病例中分割了PTV，需要四个或六个弧形束。总体而言，发现元素计划在适形指数、梯度指数和脊髓最大剂量方面优于临床计划。元素计划的PTV和脊髓平均剂量分别呈上升和下降趋势。元素计划的监测单位数量和调强因子也更高，尽管差异不显著。与临床计划相比，自动元素计划实现了更好的适形度和脊髓剂量保护，并且PTV分割成功改善了脊髓保护。
