Brain Tumors: Primary - Radiotherapy

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Stereotactic Radiosurgery

Stereotactic radiosurgery has been developed to allow highly targeted radiation to be delivered directly to the small tumors while avoiding healthy brain tissue. The term radiosurgery is used because the destruction is so precise that it acts almost like a surgical knife. Some studies suggest that stereotactic radiosurgery improves survival, even in patients with the highly aggressive glioblastoma multiforme brain cancer. The procedure is being tested to boost standard radiotherapy.

Benefits of Stereotaxy. There are numerous benefits for stereotaxy:

• Stereotaxy allows precisely focused, high-dose beams to be delivered to gliomas less than 1.25 inch in diameter.
• Investigators have found that stereotactic radiosurgery can help them reach small tumors located deep in the brain that were previously considered inoperable.
• Sometimes with stereotaxy only a single treatment may be needed.
• Unlike traditional radiotherapy, stereotactic radiotherapy can be repeated, so it is useful for recurrent tumors when a patient has already received standard radiation treatments.
• Combining stereotaxy with techniques that gauge speech and other mental functions in patients who are awake during the procedure can allow removal of brain tissue with a lower risk for complications in areas that affect such functioning.

The Planning Procedure. Stereotactic radiosurgery usually begins with a series of steps designed to plan the radiation target:

• First, the patient is given a local anesthetic. In the standard operation, the patient's head must be totally immobilized by screwing a device known as a stereotactic frame into the patient's skull. (The frame procedure is effective only on brain tumors that have regular margins.) The frame is removed as soon as the whole procedure has been completed (about 3 - 4 hours.)
• A three-dimensional map, usually using magnetic resonance imaging scans (MRI), is made of the patient's brain.
• A computer program calculates dosage levels and specific areas for radiation targeting.