Answer
X-rays and gamma rays are absorbed continuously as they pass through tissue and therefore release their energy gradually over a fairly long range. Particle beams, on the other hand, are charged, and the interaction of these charged particles with the tissue causes them to be stopped suddenly, and hence to release their energy very quickly over a short distance. This energy is therefore mostly deposited to a small portion of tissue (the tumor).
Work Step by Step
X-rays and gamma rays are absorbed continuously as they pass through tissue and therefore release their energy gradually over a fairly long range. Particle beams, on the other hand, are charged, and the interaction of these charged particles with the tissue causes them to be stopped suddenly, and hence to release their energy very quickly over a short distance. This energy is therefore mostly deposited to a small portion of tissue (the tumor)
