The direction of x-ray radiation and proton beams can be targeted with extreme accuracy. The key difference between the two therapies is that the range of a stream of protons can be precisely controlled, whereas, in the case of x-rays, this is not possible. This is due to a fundamental difference between the physical properties of electromagnetic waves (x-rays) and accelerated particles (protons).

The following pages will provide you with more information on the scientific background and consequences for therapeutic application.