Rivers Charlotte, Tranquilli Marissa, Prasad Shefalika, Winograd Evan, Plunkett Robert J, Fenstermaker Robert A, Fabiano Andrew J, Podgorsak Matthew B, Prasad Dheerendra
Department of Radiation Medicine, Roswell Park Cancer Institute, Buffalo, NY, USA.
Stereotact Funct Neurosurg. 2017;95(5):352-358. doi: 10.1159/000480666. Epub 2017 Oct 11.
PURPOSE/OBJECTIVES: The purpose of this study was to evaluate the effect of the number of brain lesions for which stereotactic radiosurgery (SRS) was performed on the dose volume relationships in normal brain.
Brain tissue was segmented using the patient's pre-SRS MRI. For each plan, the following data points were recorded: total brain volume, number of lesions treated, volume of brain receiving 8 Gy (V8), V10, V12, and V15.
A total of 225 Gamma Knife® treatments were included in this retrospective analysis. The number of lesions treated ranged from 1 to 29. The isodose for prescription ranged from 40 to 95% (mean 55%). The mean prescription dose to tumor edge was 18 Gy. The mean coverage, selectivity, conformity, and gradient index were 97.5%, 0.63, 0.56, and 3.5, respectively. The mean V12 was 9.5 cm3 (ranging from 0.5 to 59.29). There was no correlation between the number of lesions and brain V8, V12, V10, or V15. There was a direct and statistically significant relationship between the brain volume treated (V8, V10, V12, and V15) and total volume of tumors treated (p < 0.001). In our study, the integral dose to the brain exceeded 3 J when the total tumor volume exceeded 25 cm3.
The number of metastatic brain lesions treated bears no significant relationship to total brain tissue volume treated when using SRS. The fact that the integral dose to the brain exceeded 3 J when the total tumor volume exceeded 25 cm3 is useful for establishing guidelines. Although standard practice has favored using whole brain radiation therapy in patients with more than 4 lesions, a significant amount of normal brain tissue may be spared by treating these patients with SRS. SRS should be carefully considered in patients with multiple brain lesions, with the emphasis on total brain volume involved rather than the number of lesions to be treated.
目的/目标：本研究的目的是评估接受立体定向放射外科治疗（SRS）的脑病变数量对正常脑组织剂量体积关系的影响。
使用患者SRS治疗前的磁共振成像（MRI）对脑组织进行分割。对于每个计划，记录以下数据点：全脑体积、治疗的病变数量、接受8 Gy（V8）、V10、V12和V15的脑体积。
本回顾性分析共纳入225例伽玛刀治疗。治疗的病变数量从1到29不等。处方等剂量线范围为40%至95%（平均55%）。肿瘤边缘的平均处方剂量为18 Gy。平均覆盖度、选择性、适形度和梯度指数分别为97.5%、0.63、0.56和3.5。平均V12为9.5 cm³（范围为0.5至59.29）。病变数量与脑V8、V12、V10或V15之间无相关性。治疗的脑体积（V8、V10、V12和V15）与治疗的肿瘤总体积之间存在直接且具有统计学意义的关系（p < 0.001）。在我们的研究中，当肿瘤总体积超过25 cm³时，脑的积分剂量超过3 J。
使用SRS治疗时，转移性脑病变的数量与治疗的全脑组织体积无显著关系。当肿瘤总体积超过25 cm³时脑的积分剂量超过3 J这一事实有助于制定指导原则。尽管标准做法倾向于对有4个以上病变的患者使用全脑放射治疗，但对这些患者采用SRS治疗可使大量正常脑组织得以保留。对于有多个脑病变的患者，应仔细考虑采用SRS治疗，重点是受累的全脑体积而非待治疗的病变数量。
