This study explores using a special radiation treatment called **GammaTile (GT)** for people with a new diagnosis of a brain tumor called **Glioblastoma Multiforme (GBM)**. Normally, after surgery, patients receive radiation and a medicine called **temozolomide (TMZ)**. This study adds GT, a small radiation device, during surgery to see if it helps control the tumor better. GT uses a special type of radiation called **Cs-131** that works quickly and may stop the tumor from growing. The study will also use a standard approach called the **Stupp Protocol**, which combines radiation with TMZ.

• The study lasts for about 1 year and involves regular follow-up visits.
• Participants must be 18 or older and able to understand English or Spanish.
• No previous cancer treatments are allowed before joining.

Participants will receive two types of radiation and will be monitored for safety and effectiveness. This study checks if using GT right after surgery is safe and doesn’t delay other treatments. If successful, it might lead to better outcomes for patients with GBM. Please talk to your doctor to see if this study is right for you.