External radiation comes from a large machine. Generally, external radiation treatments are given 5 days a week for several weeks. The treatment schedule depends on the type and size of the tumor and the age of the patient. Giving the total dose of radiation over an extended period helps to protect healthy tissue in the area of the tumor. Depending on the material used, the implant may be left in the brain for a short time or permanently.
Implants lose a little radioactivity each day.
The patient stays in the hospital for several days while the radiation is most active. External radiation may be directed just to the tumor and the tissue close to it or, less often, to the entire brain. When the whole brain is treated, the patient often receives an extra dose of radiation to the area of the tumor. This boost can come from external radiation or from an implant. Stereotactic radiosurgery is another way to treat brain tumors.