Comparing Two Radiation Safety Margins for Brain Tumor Treatment

This trial is testing the best way to deliver radiation therapy to patients with multiple brain tumors (called metastases) in a single treatment session. Doctors want to find out whether using a smaller safety margin around the tumors works just as well as a larger margin—and whether a smaller margin might actually reduce side effects while keeping tumors under control.

Doctors around the world use different safety margins when treating multiple brain tumors with radiation, and there's no clear agreement on which size works best. This treatment method increases the risk that small positioning errors could affect how well the radiation hits the tumor. By comparing two different margin sizes, this trial will help establish the safest and most effective standard approach for all patients.