ABSTRACT
The use of proton therapy on humans was in 1954 at the University of California, Berkeley labs as pioneered by the physicist Robert Wilson and the physician Cornelius Tobias. Proton therapy beams are characterized by a range and a modulation. Multi-leaf collimators are not widely used in proton therapy centers and the collimator aperture is typically milled on site. The particle, a proton say, moves due to the force of this field. The magnetic field is oriented perpendicular to the path of the proton. Therefore, as the proton moves it experiences a force and is bent to travel in a circle. Heavy ion nuclei are much more massive than the proton and so require much more energy input to accelerate to the appropriate energy for therapy applications. Heavy ion beams require larger accelerators and larger bending magnets, resulting in much larger gantries.
