The Current Technology
Proton radiation therapy is potentially a better way to treat cancer because it has fewer side effects, but the technology is still very expensive, and of enormous scale.

Proton Radiation Therapy

By adjusting the speed of the protons, a physician can control how deep their penetration will be. The protons then release their energy at the tumor and cause less damage to the surrounding tissue. Because conventional radiation doesn't release its energy at a specified depth, it can cause more damage to the tissue surrounding the tumor.
 
Cyclotron

Using magnetic fields, the cyclotron can accelerate the hydrogen protons to two thirds the speed of light.

 

Electromagnets

The magnets focus the proton beams towards the gantry.

 

Gantry 
The gantry can rotate 360 degress around the patient to position the nozzle.

 

The Nozzle  

The brass aperture and Lucite compensator are designed to squeeze the proton beam to the size and shape of the area being treated.