Gamma Knife, also known as Gamma Knife radiosurgery (GKRS), is a form of radiosurgery, solely manufactured by Elekta AB, a Swedish company that specialises in radiation therapy systems. Common indications include vestibular schwannomas, arteriovenous malformations, brain metastases and trigeminal neuralgia 2,7.
Historically, it employed 201 cobalt-60 sources arranged in a hemispheric array. The latest system, the Gamma Knife Perfexion, uses 192 cobalt-60 sources 1.
The emitted gamma rays are focused on a target point. This allows a small volume of tissue to be treated ideally without damaging adjacent tissue.
Gamma Knife employs a standard stereotactic frame to ensure accurate targeting of the emitted beams to a precise location. This results in coagulative necrosis and glial and vascular injury 3.
Treatment may be performed in a single session or over multiple sessions 4.
Complications
Risk factors for adverse radiation effects are radiation dose and margin, volume and target location. Most patients with adverse effects remain asymptomatic; however, some patients may experience headaches, cognitive deficits, new seizures, focal neurological deficits, imbalance, and nausea/vomiting 3. Associated radiological findings include oedema and/or radiation necrosis which may produce mass effect resulting in hydrocephalus 6. Treatment involves oral steroids.
History and etymology
Gamma knife was invented by Lars Leksell, a pioneering Swedish neurosurgeon, in collaboration with a radiation biologist, Borje Larsson, and their first system was available in 1951. Lars Leksell and his son, Laurent Leksell, founded Elekta in 1972 to manufacture Gamma Knife systems 5.
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