利用剂量-面积产品评估机器人放射外科中的计划质量。

Use of dose-area product to assess plan quality in robotic radiosurgery.

机构信息

Department of Stereotaxy and Functional Neurosurgery, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50937 Cologne, Germany.

Department of Radiation Oncology, Cyberknife and Radiation Therapy, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50937 Cologne, Germany.

出版信息

Z Med Phys. 2024 Aug;34(3):428-435. doi: 10.1016/j.zemedi.2023.01.001. Epub 2023 Jan 28.

DOI:10.1016/j.zemedi.2023.01.001

PMID:36717311

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC11384082/

Abstract

PURPOSE

In robotic stereotactic radiosurgery (SRS), optimal selection of collimators from a set of fixed cones must be determined manually by trial and error. A unique and uniformly scaled metric to characterize plan quality could help identify Pareto-efficient treatment plans.

METHODS

The concept of dose-area product (DAP) was used to define a measure (DAP) of the targeting efficiency of a set of beams by relating the integral DAP of the beams to the mean dose achieved in the target volume. In a retrospective study of five clinical cases of brain metastases with representative target volumes (range: 0.5-5.68 ml) and 121 treatment plans with all possible collimator choices, the DAP was determined along with other plan metrics (conformity index CI, gradient index R50%, treatment time, total number of monitor units TotalMU, radiotoxicity index f12, and energy efficiency index η50%), and the respective Spearman's rank correlation coefficients were calculated. The ability of DAP to determine Pareto efficiency for collimator selection at DAP < 1 and DAP < 0.9 was tested using scatter plots.

RESULTS

The DAP for all plans was on average 0.95 ± 0.13 (range: 0.61-1.31). Only the variance of the DAP was strongly dependent on the number of collimators. For each target, there was a strong or very strong correlation of DAP with all other metrics of plan quality. Only for R50% and η50% was there a moderate correlation with DAP for the plans of all targets combined, as R50% and η50% strongly depended on target size. Optimal treatment plans with CI, R50%, f12, and η50% close to 1 were clearly associated with DAP < 1, and plans with DAP < 0.9 were even superior, but at the cost of longer treatment times and higher total monitor units.

CONCLUSIONS

The newly defined DAP has been demonstrated to be a metric that characterizes the target efficiency of a set of beams in robotic SRS in one single and uniformly scaled number. A DAP < 1 indicates Pareto efficiency. The trade-off between plan quality on the one hand and short treatment time or low total monitor units on the other hand is also represented by DAP.

摘要

目的

在机器人立体定向放射外科（SRS）中，必须通过反复试验手动从一组固定的准直器中选择最佳的准直器。一个独特且统一的度量标准来描述计划的质量，可以帮助识别帕累托有效的治疗计划。

方法

使用剂量面积乘积（DAP）的概念来定义一组光束的靶向效率度量（DAP），通过将光束的积分 DAP 与目标体积中的平均剂量相关联。在对 5 例脑转移瘤的代表性靶区（范围：0.5-5.68ml）和 121 个具有所有可能准直器选择的治疗计划进行回顾性研究中，确定了 DAP 以及其他计划指标（适形度指数 CI、梯度指数 R50%、治疗时间、总监测单位总数 TotalMU、放射性毒性指数 f12 和能量效率指数 η50%），并计算了各自的斯皮尔曼等级相关系数。通过散点图测试 DAP 在 DAP <1 和 DAP <0.9 时确定准直器选择的帕累托效率的能力。

结果

所有计划的 DAP 平均值为 0.95±0.13（范围：0.61-1.31）。只有 DAP 的方差强烈依赖于准直器的数量。对于每个靶区，DAP 与所有其他计划质量指标均具有很强或非常强的相关性。只有对于 R50%和 η50%，对于所有靶区的计划组合，DAP 具有中度相关性，因为 R50%和 η50%强烈依赖于靶区大小。CI、R50%、f12 和 η50%接近 1 的最佳治疗计划与 DAP <1 明显相关，而 DAP <0.9 的计划甚至更好，但代价是治疗时间更长和总监测单位更高。