UNIty-Based MR-Linac Guided Adaptive RadioThErapy for High GraDe Glioma-3 (UNITED-3)

This study is testing a precision radiation technique called MR-Linac guided adaptive radiotherapy for newly diagnosed grade 4 brain tumors (glioblastoma or grade 4 astrocytoma). Using an MRI scanner combined with a radiation machine, doctors can reshape the radiation treatment in real time at each session, adapting to how the tumor changes during the course of treatment. **You may be eligible if...** - You have a confirmed grade 4 brain tumor (glioblastoma or grade 4 astrocytoma) diagnosed by biopsy or surgery within the last 12 weeks - You are well enough to receive full radiation therapy with concurrent systemic treatment (ECOG 0-2) - Your kidney, liver, and blood count levels are within acceptable ranges - You are able to lie flat for at least 30 minutes and tolerate the MRI environment **You may NOT be eligible if...** - You have a pacemaker, metal implants, or other MRI contraindications - You cannot tolerate the head immobilization required during treatment - You have previously received brain radiation - You have severe kidney impairment preventing gadolinium contrast use (unless on dialysis) Talk to your doctor to see if this trial is right for you.