Cyberknife Radiosurgery for Patients With Brain Metastases Diagnosed With Either SPACE or MPRAGE Sequence

"All patients will receive a pre-treatment cranial MRI for diagnostic and treatment planning purposes.~In Arm A, the contrast-based T1-weighted SPACE sequence is utilized for GTV definition. In Arm B, the contrast-based T1-weighted three-dimensional MPRAGE sequence is utilized for GTV definition. In both cases the GTV consists of all contrasted tissue associated with the target lesion and all additional tissue judged by an experienced physician to be part of the suspect target lesion. To the GTV a PTV margin of 1 mm is added by isotropic expansion that can be slightly modified if deemed necessary by the treating physician (e.g. intersection with adjoining OAR).~Dose prescription to the PTV for target lesions will be as follows:~* 20 Gy to the 70%-isodose (lesions \< 2 cm max. diameter)~* 18 Gy to the 70%-isodose (lesions 2 - 3 cm max. diameter)~* 6 x 5 Gy to the conformally surrounding isodose (lesions \> 3 cm max. diameter)"