The journey from proton to gamma knife.
It was generally accepted by the early 1960s that proton beam radiosurgery was too complex and impractical. The need was seen for a new machine. The beam design had to be as good as a proton beam. It was also decided that a static design was preferable even if the evolution of that notion is no longer clear. Complex collimators were designed that using sources of cobalt-60 could produce beams with characteristics adequately close to those of proton beams. The geometry of the machine was determined including the distance of the sources from the patient the optimal distance between the sources. The first gamma unit was built with private money with no contribution from the Swedish state, which nonetheless required detailed design information in order to ensure radiation safety. This original machine was built with rectangular collimators to produce lesions for thalamotomy for functional work. However, with the introduction of dopamine analogs, this indication virtually disappeared overnight.
Jeremy C
JC
Ganz
D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D061766:Proton Therapy / Q000266:history*; D011522:Protons / Q000266:history*; D016634:Radiosurgery / Q000266:history*
D011522:Protons
beam requirements; gamma unit; physical principles; proton beam replacement; radiation volume shaping; relative biological efficiency