Proton therapy uses a narrow, focused beam of protons to deliver radiation therapy to diseased tissue, most often in the treatment of cancer. This type of treatment lets cancer physicians treat the disease in a more aggressive manner, while at the same time keeping side effects to a minimum and leaving healthy tissue relatively unharmed. There are only a handful of proton therapy centers in the United States, and each has the capability to treat as many as 200 patients a day.
How It Works
Atoms that carry a positive charge are called protons, and doctors can use a beam of these atoms to irradiate tumors. These protons will release the majority of their energy when they reach a tumor so that no radiation damages the surrounding tissue. In other words, the radiation dose prescribed by the physician will target the tumor better while reducing the amount of damage done to the patient. This lets the radiation oncologist treat a tumor with a greater dose and minimize unwanted side effects. This ability is especially important when treating the growing, developing and changing tissues in children with cancer.
Equipment
Proton therapy uses a machine called a cyclotron or a synchrotron that generates and then accelerates protons. The protons are guided out of the machine by magnets aimed at the tumor. These machines, sometimes called gantries as well, can rotate around patients to target difficult areas. Proton beams can be shaped by focusing them through replica molds of the tumor for an even more effective treatment.
The Science
When protons pass near electrons, the protons' positive charge attracts the negatively charged electrons in a process called ionization. Changes take place within the atom, and the molecule in which the atom exists. Ionization allows radiation to damage molecules in the cells, particularly the DNA. Altering the DNA destroys several cell functions, but the important function when it comes to cancer treatment is the cell's ability to divide. Enzymes will try to repair the damaged DNA, the radiation does too much harm and the enzymes fail. The cancer cell has a harder time repairing damage normally, and when doctors introduce radiation to the process the cancer cells frequently die off.
Benefits
Proton therapy is preferable to traditional x-ray radiation treatments for several reasons. It is more precise, leaving healthy tissue unharmed. This leads to a better quality of life, since pain is removed from the equation and the treatments are done on an out-patient basis.
Cancers Eligible for Treatment
As of 2009, proton therapy is being used to treat only certain types of tumors. The following areas and tumors have been treated with proton therapy: the lungs, the prostate, the brain, tumors of the spine or vertebrae, skull base sarcomas, brain tumors in children, tumors of the head and neck, and eye melanomas. Clinical trials are being conducted on other parts of the body, many with promising results.
Tags: brain tumors, healthy tissue, leaving healthy, leaving healthy tissue, positive charge, Proton therapy, proton therapy
