Changing the gamma knife

The first Gamma Knife used helmets containing collimators of different diameters that increase the flexibility of the treatment. Changing these helmets was time-consuming and tedious. The original model that was introduced into the United States was the U model where the patient was inserted into the machine inward and upward, using hydraulics. A new simpler machine was devised called the B model where the patient simply moved in and out, but there was still the problem of changing helmets. Then, the C model was introduced, with a robot called the automatic positioning system that permitted the patient’s position to be moved automatically. However, the helmets still had to be changed when collimators of different sizes were required. Finally, an entirely redesigned model called Perfexion was introduced where there were no helmets and the patient once placed in the machine would be treated completely following a single pressure on a button.