Moiseenko Vitali, Grimm Jimm, Yorke Ellen, Jackson Andrew, Yip Anthony, Huynh-Le Minh-Phuong, Mahadevan Anand, Forster Kenneth, Milano Michael T, Hattangadi-Gluth Jona A
Radiation Medicine and Applied Sciences, University of California San Diego Moores Cancer Center, La Jolla, USA.
Radiation Oncology, Geisinger Health System, Danville, USA.
Cureus. 2020 Oct 5;12(10):e10808. doi: 10.7759/cureus.10808.
Background and purpose Recently published HyTEC report summarized lung toxicity data and proposed guidelines of mean lung dose (MLD) <8 Gy and normal lung receiving at least 20 Gy, V<10-15% to avoid lung toxicity. Support for preferred use of a particular dosimetric parameter has been limited. We performed a detailed dose-volume analysis of data on radiation pneumonitis (RP) following lung stereotactic body radiation therapy (SBRT) to search for parameters showing the strongest correlation with RP. Materials and methods Two patient cohorts (primary and metastatic lung tumor patients) from previously reported studies were analyzed. Total number of patients was 96, and incidence of grade ≥2 RP was 13.5% (13/96). Fitting to the logistic function was performed to investigate correlation between incidence of RP and reported dosimetric and volumetric parameters. Another independent cohort was used to explore correlation between dosimetric parameters. Results Among normal lung parameters (MLD and reported V), only MLD consistently showed significant correlation with incidence of RP. Gross tumor volume (GTV), internal target volume, planning target volume (PTV), and minimum dose covering 95% of GTV or PTV did not show statistical significance. A significant correlation between reported V and MLD was observed in all cohorts. Conclusions In considering tumor- and target-specific (e.g., GTV, PTV) and normal lung-specific (e.g., MLD, V) metrics, MLD was the only parameter that consistently correlated with incidence of RP across both cohorts. Because SBRT planning constraints allow small normal lung volumes to receive high doses, utility of MLD is not obvious. The parallel structure of lung is one possible explanation, but correlation between dosimetric parameters obscures elucidation of the preferred or mechanistically based parameter to guide radiotherapy planning.
背景与目的 最近发表的HyTEC报告总结了肺毒性数据，并提出了平均肺剂量（MLD）<8 Gy以及正常肺接受至少20 Gy且V<10 - 15%以避免肺毒性的指南。对特定剂量学参数优先使用的支持有限。我们对肺立体定向体部放射治疗（SBRT）后放射性肺炎（RP）的数据进行了详细的剂量 - 体积分析，以寻找与RP相关性最强的参数。材料与方法 分析了先前报道研究中的两个患者队列（原发性和转移性肺肿瘤患者）。患者总数为96例，≥2级RP的发生率为13.5%（13/96）。采用逻辑函数拟合来研究RP发生率与报告的剂量学和体积参数之间的相关性。另一个独立队列用于探索剂量学参数之间的相关性。结果 在正常肺参数（MLD和报告的V）中，只有MLD始终与RP发生率显示出显著相关性。肿瘤总体积（GTV）、内靶体积、计划靶体积（PTV）以及覆盖95% GTV或PTV的最小剂量均未显示出统计学意义。在所有队列中均观察到报告的V与MLD之间存在显著相关性。结论 在考虑肿瘤和靶区特异性（如GTV、PTV）以及正常肺特异性（如MLD、V）指标时，MLD是两个队列中唯一始终与RP发生率相关的参数。由于SBRT计划限制允许小体积的正常肺接受高剂量，MLD的实用性并不明显。肺的平行结构是一种可能的解释，但剂量学参数之间的相关性掩盖了对指导放射治疗计划的首选或基于机制的参数的阐明。
