Perfexion Brain Metastasis (HF-SRT)

With increasing volume of tumor, the dose of radiosurgery that can be safely delivered to recurrent oligo-metastases in the brain must be reduced. However, reducing the dose of radiosurgery also compromises local control. There is mounting evidence of a local control benefit to a hypofractionated approach in radiation delivery for brain metastases compared with single fraction radiosurgery. Here we propose a novel therapeutic strategy that builds on this concept whereby time between each delivered fraction will enable us to measure and adapt to response, with the objective of reducing irradiated volumes and improving outcomes. In general, the treatment of malignant tumors benefits from fractionation of the dose due to a number of radiobiological properties (redistribution, reoxygenation, repair) that distinguish, and select against, malignant lesions in the fractionation process. Hypofractionated stereotactic radiotherapy (HSRT) is a method of delivering a highly conformal dose distribution in a few treatment sessions using a relocatable stereotactic frame. HSRT may be an attractive alternative to SRS because it may 1) improve patient comfort by removing the invasive nature of SRS frames, 2) confer a radiobiologic advantage over single fraction treatment.