Particle therapy

Overview
Particle therapy is a form of external beam radiotherapy utilizing beams of protons, neutrons, or atomic nuclei. The most common type of particle therapy as of 2007 is proton therapy. Strictly speaking, a photon, used in x-ray or gamma ray therapy can also be considered a particle, but generally that distinction is ignored in the context of radiation therapy. Additionally, electron therapy is generally put in its own category. Because of this, particle therapy is sometimes referred to as hadron therapy.

In contrast to photons, charged particles deposit most of their energy at a specific depth inside the tissue dependent on the energy of the particles. This deposition occurs at the Bragg peak. The advantage of this energy depostion profile is that less energy is deposited into the normal tissue surrounding the target tissue.

Heavy ion therapy is the use of particles more massive than protons or neutrons, such as carbon nuclei for particle therapy.

Combined particle therapy refers to treating a tumor with more than one type of particle therapy (e.g. using both proton and carbon ion therapy).

Particle Therapy in the United States
There are a number of clinics and research centers offering proton therapy in the United States.

In July 2007, Touro University College of Osteopathic medicine announced in a press release plans to build a center for particle therapy cancer treatment in California that will offer both proton and carbon ion therapy. Upon completeion, it would be the first such center in the United States.