Alain C. J. de Lotbinière, M.D.
Almost half a century ago, the Swedish neurosurgeon and scientist, Lars Leksell, conceived an idea whose application would take many years to realize: namely, that by substituting a probe penetrating the depths of the brain with narrow beams of radiant energy aimed towards a precise target, he could selectively destroy discrete fiber tracts or nuclei within the brain without so much as a skin incision.
Lars Leksell's relentless devotion to perfecting an ideal instrument for radiosurgery (or "closed intracranial surgery" as he named it) led him to investigate many different radiation-emitting devices. Among those instruments which he used or considered for radiosurgery were the 185 MeV synchrocyclotron in Uppsala, Sweden and the linear accelerator before realizing his goal with the construction of the first Gamma Knife in 1967, an achievement which only became possible with the collaboration of Börje Larsson. Twenty years later the first North American 201 Cobalt-60 source Gamma Knife was installed in the United States and today over 100 units are in operation worldwide. The recognition that the Gamma Knife is the gold standard for stereotactic radiosurgery explains why so many major centers have selected it over other competing radiosurgical systems. Yale-New Haven Ambulatory Services is proud to join major teaching institutions on the list of facilities which have chose to acquire the Gamma Knife and is the only radiosurgery facility in Connecticut to possess such an instrument.
The Principle
Stereotactic radiosurgery is defined as the delivery of a single, high dose of radiation through the intact skull to a small and critically located intracranial volume. The Gamma Knife contains 201 cobalt-60 sources of approximately 30 curies each at the time of loading, placed in a hemispherical array in a heavily shielded unit. A collimator helmet focuses the radiation to a specific target point within the head with sub-millimeter positioning accuracy in such a fashion that a high dose of radiation is delivered to the target while sparing the surrounding tissue. Complex-shaped lesions are treated by combining collimators of different sizes with selected beam blocking and weighting using a sophisticated computer planning system. This ensures that tight conformation of the does to the edge of the target volume is achieved such that each patient receives a "tailored" plan.
Safety and Efficacy
Unlike the linear accelerator, the Gamma Knife has few moving parts thereby eliminating many sources of inaccuracy and unreliability. Because the radiation fall off is very steep outside the target area, the surrounding brain receives minimal radiation thereby sparing harmful delayed side effects to neighboring critical structures. Many of the risks of open surgery are eliminated with Gamma Knife radiosurgery, making the procedure particularly useful in patients with advanced age or in those patients with other illnesses where conventional surgery would pose an unacceptably high risk. Finally, the efficacy and cost effectiveness of the Gamma Knife treatment have been proven in numerous studies when comparing it to the alternative, namely open surgery.
Who can benefit from this treatment? Indications at present include:
- Benign tumors such as meningiomas, acoustic neuromas, pituitary adenomas and craniopharyngiomas
- Primary or recurrent malignant brain tumors such as astrocytomas or oligodendrogliomas
- Solitary and multiple brain metastases
- Head and neck tumors such as nasopharyngeal carcinomas and ocular melanomas
- Arteriovenous malformations (AVMs)
- Trigeminal neuralgia
- Intractable pain secondary to cancer
- Movement disorders such as Parkinson's disease and essential tumor
In addition, the Gamma Knife is being used as an investigational tool for certain forms of epilepsy and psychiatric disease. Patients referred to the Yale-New Haven Gamma Knife Center will be evaluated by team specialists with extensive experience, including neurosurgeons, radiation oncologists and neuroradiologists. Candidates for the procedure are selected for treatment only after a thorough review of all prior records and imaging studies.
Benefits of Gamma Knife Treatment
Since Gamma Knife radiosurgery requires no incisions and is performed under local anesthesia with mild sedation, the risks of infections and adverse reactions to general anesthesia are eliminated. Patients experience minimal pain and are therefore able to return to their former activities without discomfort or restrictions. Hospitalization is either minimized or not required. This results in a significant cost savings over conventional surgery. Because only the target tissue is irradiated, sparing the surrounding brain, hair loss is eliminated and secondary reactions such as nausea and epileptic seizures are minimized. Finally, the accumulated experience of over 30 years of treatment using the Gamma Knife allows for predictable outcomes with a high degree of accuracy.
The Yale Gamma Knife Center can be reached at 203-785-2808
or email to alain.delotbiniere@yale.edu
Neurosurgery Faculty/Program Menu
Department of Neurosurgery address and phone number
http://info.yale.med.edu/surgery/neurosur/gammaknife.html
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