UNIVERSITY OF FLORIDA: SHANDS NEUROLOGICAL CENTER
Fractionated Radiosurgery : The Pre-LINAC Evaluation
Patients with lesions located in or near radiation-sensitive areas of the brain may be candidates for an investigational procedure known as fractionated stereotactic radiotherapy.
These tumors can now be treated more effectively and with fewer side effects because of improvements in technologies developed at the University of Florida Brain Institute that spare surrounding normal brain tissue.
Until recently, almost all stereotactic radiosurgery procedures, because of their reliance on a head ring attached to the skull, were delivered as one large dose of precisely focused radiation. Certain lesions, because of size or proximity to vital neurological structures such as the optic nerves, could not be safely treated with this technology. The alternative was conventional radiation therapy, which uses much smaller doses of radiation, applied once or twice daily for many weeks.
However, because conventional radiation therapy does not use stereotactic positioning and focusing techniques, a large margin of normal brain tissue was usually included in the treatment field. In some patients, this produced significant long-term side effects, such as diminished cognitive brain function.
Recently, the UF radiosurgery team developed and tested a new system for accurately positioning patients that uses a painless bite plate that easily fits in the patient's mouth. An infrared camera and computer system detects light-emitting diodes (LEDs) attached to the bite plate and allows the patient to be very accurately positioned on a repeated basis.
This allows lesions not treatable with single-dose radiosurgery to be treated with very precisely applied beams of radiation, in small doses over several weeks, without exposing a margin of normal brain tissue to potentially injurious radiation. This new methodology is, therefore, a combination of the stereotactic positioning technology developed for radiosurgery, and the small-dose, many-treatment approach used in conventional radiation therapy. It is called fractionated stereotactic radiotherapy.
Referring physicians should send actual CT and MRI films, as well as hospital and office records, to the University of Florida, College of Medicine, Department of Neurosurgery.
Risks of LINAC Treatment
There is no known acute risk of radiosurgical therapy, which allows patients to be treated on an outpatient basis. The long-term risks and benefits of this form of radiosurgical treatment are currently under investigation.
Post-LINAC Treatment
Follow-up assessment of patients involves periodic MRI scans after treatment. Patients may choose to have follow-up X-rays taken at medical facilities other than Shands Hospital at the University of Florida.
Indications for Radiosurgical Treatment
General indications for radiosurgical treatment, as opposed to open surgical treatment, are as follows:
1. Surgically inoperable lesions.
2. Lesions that have recurred or persisted after surgery.
3. Medically infirm patients.
4. Patients who refuse open surgical treatment.