Irradiated Volume as a Predictor of Brain Radionecrosis After Linear Accelerator Stereotactic Radiosurgery

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• 作者：Brian J. Blonigen ; Ryan D. Steinmetz ; Linda Levin ; Michael A. Lamba ; Ronald E. Warnick ; John C. Breneman
• 刊名：International Journal of Radiation Oncology*Biology*Physics
• 出版年：2010
• 出版时间：15 July 2010
• 年：2010
• 卷：77
• 期：4
• 页码：996-1001
• 全文大小：162 K

文摘

Purpose

To investigate the correlation between volume of brain irradiated by stereotactic radiosurgery (SRS) and the incidence of symptomatic and asymptomatic brain radionecrosis (RN).

Methods and Materials

A retrospective analysis was performed of patients treated with single-fraction SRS for brain metastases at our institution. Patients with at least 6-month imaging follow-up were included and diagnosed with RN according to a combination of criteria, including appearance on serial imaging and histology. Univariate and multivariate analyses were performed to determine the predictive value of multiple variables, including volume of brain receiving a specific dose (V8 Gy–V18 Gy).

Results

Sixty-three patients were reviewed, with a total of 173 lesions. Most patients (63 % ) had received previous whole-brain irradiation. Mean prescribed SRS dose was 18 Gy. Symptomatic RN was observed in 10 % and asymptomatic RN in 4 % of lesions treated. Multivariate regression analysis showed V8 Gy–V16 Gy to be most predictive of symptomatic RN (p < 0.0001). Threshold volumes for significant rise in RN rates occurred between the 75th and 90th percentiles, with a midpoint volume of 10.45 cm³ for V10 Gy and 7.85 cm³ for V12 Gy.

Conclusions

Analysis of patient and treatment variables revealed V8 Gy–V16 Gy to be the best predictors for RN using linear accelerator–based single-fraction SRS for brain metastases. We propose that patients with V10 Gy >10.5 cm³ or V12 Gy >7.9 cm³ be considered for hypofractionated rather than single-fraction treatment, to minimize the risk of symptomatic RN.