gamma knife

gamma Knife

a minimally invasive radiosurgical system used in the treatment of benign and malignant intracranial neoplasms and arteriovenous malformations.
See also: radiosurgery.

Gamma Knife is a registered trademark of Elekta Radiosurgery of Atlanta, Georgia. The system was developed in the late 1960s by Lars Leksell and Borge Larsson of Sweden. As a preliminary to use of the Gamma Knife, the lesion to be ablated is precisely located by imaging techniques such as MRI, CT, PET, and angiography. Beams of gamma rays from 200 cobalt-60 sources are then directed by a computer so that they converge on the lesion. A series of exposures are made during a period of about 1 hour. Lesions larger than about 3 cm cannot be treated. The mechanism is bulky and costly, but the procedure has shown a success rate of about 85% in the treatment of arteriovenous malformations and 50-95% percent for neoplasms. Besides avoiding the risks and complications of open surgery, the Gamma Knife permits treatment of lesions the location of which prohibits any attempt at surgical removal. In addition, patient discomfort is minimal and most patients remain in the hospital for only 1 night. Many return home, or even to work, on the day of treatment. The Gamma Knife has demonstrated limited usefulness in the treatment of other disorders, such as tumors of the eye and the pituitary gland, trigeminal neuralgia, epilepsy, parkinsonism, and other movement disorders.

Gamma Knife

A trademark for a radiologic nonsurgical device used in stereotactic radiosurgery.

gamma knife

Radiation oncology An RT device that provides 201 stereotactically focused beams of γ radiation from 60Co that destroys intracranial targets; the GK and linear accelerators can be adapted to irradiate localized regions of the brain Indications AV malformations, meningiomas, acoustic neuromas, pituitary adenomas, craniopharyngiomas, 1º and 2º tumors

Gamma knife

A surgical tool that focuses beams of radiation at the head, which converge in the brain to form a lesion.

Mentioned in: Brain Tumor, Psychosurgery

Gam·ma Knife

(gamă nīf)

Minimally invasive radiosurgical system used to treat benign and malignant intracranial neoplasms and arteriovenous malformations. [Gamma Knife is a registered trademark of Elekta Radiosurgery of Atlanta, Georgia.]