UNITy-BasED MR-Linac Adaptive Simultaneous Integrated Hypofractionated Boost Trial for High Grade Glioma in the Elderly

This trial is testing an adaptive radiation therapy approach using an MRI-guided radiation machine (MR-Linac) for elderly patients with glioblastoma — an aggressive brain tumor. The study tests whether a shorter, more intense radiation course tailored in real-time to the tumor's shape can be safely and effectively delivered alongside standard chemotherapy. **You may be eligible if...** - You are 65 years of age or older - You have been diagnosed with glioblastoma (WHO grade 4) or IDH-mutant grade 4 astrocytoma confirmed by biopsy or surgery within the past 6 weeks - Your doctors believe you can tolerate 15 daily radiation sessions (3 weeks) with chemotherapy - Your performance status is ECOG 0, 1, or 2 - You are expected to survive at least 12 weeks - You can have MRI scans (with contrast) **You may NOT be eligible if...** - You cannot have an MRI (e.g., incompatible metal implants) - You cannot lie flat on your back for at least 90 minutes - You cannot tolerate a head immobilization mask - You weigh over 140 kg or have a very large body circumference (>60 cm) - You have had prior brain radiation - The tumor involves the brainstem or has spread throughout the membranes covering the brain Talk to your doctor to see if this trial is right for you.