Gamma Knife Stereotactic Radiosurgery

The Leksell Gamma Knife is a stereotactic radiosurgery device that allows a neurosurgeon and radiation oncologist to treat abnormalities that are intracranial (inside the skull), without using an actual knife.

This is a form of radiosurgery that uses 201 carefully focused beams of radiation from Cobalt-60 sources that are contained in the Gamma Knife unit. The treatment is usually conducted in a single treatment as an outpatient, or with an overnight stay at the hospital or observation unit. Helmet with Collimators

The radiosurgical treatment is accurate to within less than a millimeter; and therefore, very little significant radiation is delivered to the surrounding normal tissues. The radiation is focused on the abnormality to be treated through small openings in a shielded helmet into which the patient’s head is inserted during the procedure.

The Gamma Knife was developed conceptually by Dr. Lars Leksell in 1949 in Stockholm, Sweden. After years of research and development the first Gamma Knife unit became operational in 1967 at the Karolinska Institute in Stockholm.

There are over 2,500 scientific publications that have reported and supported the use of this non-invasive alternative for the treatment of many intracranial tumors and other conditions.

The Gamma Knife involves no incision, minimal pain and greatly reduced risk for the patient. In addition, it offers new hope for a variety of lesions that previously were unsuccessfully treated by conventional surgery, chemotherapy or radiation therapy.

Modern brain imaging with CT and MR techniques and sophisticated computers allow GK radiosurgery for many tumors, vascular abnormalities, and pain problems which are now treated by open surgery. The results of treatment are very beneficial in most cases, optimistic in others, and under going continuing evaluation in all cases. Here is a partial list of some intracranial diseases treated by the Gamma Knife:

What Brain Disorders Can Gamma Knife Radiosurgery Treat ?

Brain tumors:

• Glioblastomas
• Anaplastic astrocytomas
• Gliomas/ Astrocytomas
• Oligodendrogliomas
• Ependymomas
• Pilocytic astrocytomas
• Meningiomas
• Pituitary tumors
• Pineal region tumors
• Acoustic Neuromas
• Neuromas of the cranial nerves
• Glomus jugulare tumors
• Metastatic brain tumors Skull base tumors
• Invasive squamous and basal cell carcinomas
• Chordomas
• Chondrosarchomas
• Esthesioneuroblastomas Vascular abnormalities:
• Arteriovenous malformations
• Cavernous malformations Functional problems:
• Trigeminal neuralgia
• Parkinson’s disease Ocular tumors
• Uveal melamona
• Orbital metastases
• Optic nerve sheath meningioma

How does it work?

The Gamma Knife contains 201 small cobalt sources of gamma rays arrayed in a hemisphere within a thickly shielded structure. This radiant energy is focused into overlapping beams by collimators. The focal point of the collimators is extremely intense. The treatment planning software allows the focal point to be accurately placed on the target volume.

Preparation and Treatment Planning:

After your case has been carefully reviewed by the radiation oncologist and neurosurgical team, if you are a candidate for Gamma Knife Radiosurgery you will be scheduled to go to the Gamma Knife Unit located at the Pitt County Memorial Hospital in Greenville, NC for your treatment.Early in the morning a lightweight aluminum frame is fixed to the head using local anesthesia and possibly intravenous, conscious sedation.

This procedure takes a short time and well tolerated. The frame remains in place until the end of treatment later in the day. After frame placement patients undergo CT or MR imaging. Patients with vascular abnormalities may undergo an angiogram. These images are used for treatment planning purposes.

The greatest advances since the first Gamma Knife treatment in 1968 have been the advent of CT and MR imaging as well as high speed data processing which allows surgeons to treat intracranial disease with computer techniques.

The CT/ MR images are displayed by software designed for conformal treatment planning. This allows the Gamma Knife’s highly focused energy to accumulate within the target volume while minimizing radiation to sensitive adjacent brain tissue. The neurosurgeon, radiation oncologist and physicist develop the conformal treatment plan.

The computer software reduces the treatment plan to a list of simple instructions to guide the gamma rays to the target. The patient’s stereotactic head frame is fixed within the collimator for each treatment. Usually several shots are used to cover the entire target volume. Total treatment time varies from 45 minutes to 1½ hours. Following treatment, the frame is removed and patients are observed overnight or are discharged home.

Additional information will become available over hte next several weeks. Please check back for updates.

If you think that you have one of the conditions for which you may be a candidate for Gamma Knife Stereotactic Radiosurgery, you may contact the staff at the Carolina Radiation Medicine Cancer Treatment Center at 252-329-0025 to request a consult and evaluation by one of the CRM Gamma Knife Credentialed Radiation Oncologists and a neurosurgeon on the Gamma Knife treatment team.

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