Irradiated volume as a predictor of brain radionecrosis after linear accelerator stereotactic radiosurgery.

To investigate the correlation between volume of brain irradiated by stereotactic radiosurgery (SRS) and the incidence of symptomatic and asymptomatic brain radionecrosis (RN). 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). 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 cm(3) for V10 Gy and 7.85 cm(3) for V12 Gy. 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 cm(3) or V12 Gy >7.9 cm(3) be considered for hypofractionated rather than single-fraction treatment, to minimize the risk of symptomatic RN.

Blonigen BJ ，Steinmetz RD ，Levin L ，Lamba MA ，Warnick RE ，Breneman JC ... -  《-》

Radiation-induced changes of brain tissue after radiosurgery in patients with arteriovenous malformations: correlation with dose distribution parameters.

Levegrün S ，Hof H ，Essig M ，Schlegel W ，Debus J ... -  《INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS》

Stereotactic radiosurgical treatment in 103 patients for 153 cerebral melanoma metastases.

Selek U ，Chang EL ，Hassenbusch SJ 3rd ，Shiu AS ，Lang FF ，Allen P ，Weinberg J ，Sawaya R ，Maor MH ... -  《INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS》

The impact of whole-brain radiation therapy on the long-term control and morbidity of patients surviving more than one year after gamma knife radiosurgery for brain metastases.

Varlotto JM ，Flickinger JC ，Niranjan A ，Bhatnagar A ，Kondziolka D ，Lunsford LD ... -  《INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS》

Stereotactic radiosurgery for treatment of spinal metastases recurring in close proximity to previously irradiated spinal cord.

As the spinal cord tolerance often precludes reirradiation with conventional techniques, local recurrence within a previously irradiated field presents a treatment challenge. We retrospectively reviewed 51 lesions in 42 patients treated from 2002 to 2008 whose spinal metastases recurred in a previous radiation field (median previous spinal cord dose of 40 Gy) and were subsequently treated with stereotactic radiosurgery (SRS). SRS was delivered to a median marginal dose of 20 Gy (range, 10-30 Gy) in 1-5 fractions (median, 2), targeting a median tumor volume of 10.3 cm(3) (range, 0.2-128.6 cm(3)). Converting the SRS regimens with the linear quadratic model (α/β = 3), the median spinal cord maximum single-session equivalent dose (SSED) was 12.1 Gy(3) (range, 4.7-19.3 Gy(3)). With a median follow-up of 7 months (range, 2-47 months), the Kaplan-Meier local control and overall survival rates at 6/12 months were 87%/73% and 81%/68%, respectively. A time to retreatment of ≤12 months and the combination of time to retreatment of ≤12 months with an SSED of <15 Gy(10) were significant predictors of local failure on univariate and multivariate analyses. In patients with a retreatment interval of <12 months, 6/12 month local control rates were 88%/58%, with a SSED of >15 Gy(10), compared to 45%/0% with <15 Gy(10), respectively. One patient (2%) experienced Grade 4 neurotoxicity. SRS is safe and effective in the treatment of spinal metastases recurring in previously irradiated fields. Tumor recurrence within 12 months may correlate with biologic aggressiveness and require higher SRS doses (SSED >15 Gy(10)). Further research is needed to define the partial volume retreatment tolerance of the spinal cord and the optimal target dose.

Choi CY ，Adler JR ，Gibbs IC ，Chang SD ，Jackson PS ，Minn AY ，Lieberson RE ，Soltys SG ... -  《-》