How it began
In the 1950s Lars Leksell, professor of neurosurgery at the Karolinska Institute in Stockholm, and Börje Larsson, a radiation biologist at the Gustaf Werner Institute of Uppsala University, began to investigate combining radiation beams with stereotactic guiding devices able to pinpoint targets within the brain. By 1967 they had arranged for the construction of the first Gamma Knife, using cobalt-60 as the energy source. The prototype was completed at Sophiahemmet Hospital in Stockholm, and Leksell called the technique stereotactic radiosurgery. The aim was to treat targets in the brain without an open surgical procedure.
How it works
The Gamma Knife combines beams of gamma radiation with a stereotactic guiding device that pinpoints a target within the brain. The radiation comes from sources of cobalt-60; the model installed in Pittsburgh in 1987 had 201 of them. Later units added variable beam diameters, a redesigned patient bed and robotics that position the target, which made dose delivery more efficient and gave access to more tumors.
How it spread
In 1987 Presbyterian University Hospital in Pittsburgh installed the first 201-source Gamma Knife in North America, at the time only the fifth unit in the world. By 1990 long-term results showed high rates of brain tumor control and successful closure of arteriovenous malformations.
What changed first
The prototype was used for 12 years in Sweden. It was designed for functional neurological surgery: treating patients with pain, movement disorders and certain behavioral disorders that had not responded to conventional psychiatric treatment. Seeing its potential against brain tumors, Leksell and his colleagues built a second unit in 1975, installed at the Karolinska Institute, where it became part of the neurosurgical service.
Where it stands today
Later models added robotics, variable beam diameters and, in the Leksell Gamma Knife Icon of 2016, an on-board CT scanner. Indications now include brain metastases, deep skull base tumors and malignant brain tumors. The Pittsburgh center alone reports more than 17,000 patients treated.
