Radiation therapy can be classified according to the types of radiation particles or waves that are used to deliver the treatment. The three major types of radiation therapy are photons, electrons, or protons. While all three types have similar effects on tumor tissue and damage cancer cells, photons and electrons are the most readily available, greatest commonly used, and best-established ways to deliver radiation therapy.
Two radiation therapy treatments you hear a lot about today are CyberKnife and Proton Therapy. CyberKnife uses photons, the same type of beams used in X-ray machines. However, in radiation therapy, much higher energy photon beams, called stereotactic body radiation therapy (SBRT), are used. Using many different angles to focus the radiation at one small point, SBRT delivers a high dose of radiation very precisely to a tumor. By using a large number of beam angles to deliver the radiation, SBRT lowers the effects on the normal tissue, which the radiation passes through, but delivers a large dose of radiation to a single point where all of the beams come together at the tumor site. Proton Therapy has the capability of minimizing damage to healthy tissue through the use of particle therapy. During proton therapy, doctors determine the precise point in a patient’s body where the proton releases the majority of energy, maximizing exposure to the treatment area.
While both treatments are forms of radiation therapy, CyberKnife has advantages over Proton Therapy, including the number of treatments needed (only three to five days compared to the six to seven weeks needed for Proton Therapy) and continuous correction for breathing and movement during treatment, further reducing normal tissue exposure to radiation. Proton Therapy is still not widely available because the machines that produce and deliver protons are extremely large, need dedicated space, and are very expensive. Because of this, Proton Therapy is only available in a small number of centers around the country which may delay or prevent treatment for patients who need treatment quickly. Also, due to the high cost of Proton Therapy, some insurance companies may not approve payment of the treatment.
When it comes to radiation therapy, there are lots of different treatment options. If possible, patients should take the time to discuss these options with their physician, or try to learn as much as they can, to determine which treatment is best for them and their type of cancer or condition.