Radiation therapy (also called therapeutic radiology or radiation oncology) uses X-rays, gamma rays, and charged particles to fight cancer. Like surgery, radiation therapy is used in several ways depending on the type and location of the cancer. Certain levels of radiation work to destroy cancer cells or prevent cells from growing or reproducing. This treatment may provide a cure for cancer, control the disease, or help relieve its symptoms. Most radiation treatments do not make you radioactive. Talk with your doctor about any precautions you should take when getting radiation therapy.
Although each hospital may have specific protocols, radiation therapy usually begins with these procedures:
- Simulation process. After a physical examination and a review of your medical history, your treatment team maps out the position you will be in for each treatment and the exact location on your body (referred to as treatment field or port) where the radiation will be given. Sometimes, the area on your body that requires treatment will be marked to make sure radiation is given properly. The treatment team may also make molds, headrests, or other devices that help to position you during your treatment. Imaging studies, such as CT scans, MRI scans or PET scans, may also be performed during the simulation process to help plan how to direct the radiation during your treatments.
- Treatment plan. Once the simulation process is completed, the radiation oncologist will determine your treatment plan, including the type of machine to use, the amount (dose) of radiation that is needed, and the number of treatments that will be given.
Radiation therapy is given through different methods, depending on the type of cancer, the location of the cancer, and the patient's health. Sometimes, radiation therapy is used in combination with other treatments. The following are some of the different types of radiation therapy with brief explanations of their goals:
- External radiation (external beam therapy). With external radiation, radiation is administered by a large machine that points the energy waves directly at the tumor. The radiation therapist controls the machine. Since radiation is used to kill cancer cells, special shields may be made to protect the tissue surrounding the treatment area. Radiation treatments are painless and usually last a few minutes.
- Internal radiation (brachytherapy, implant radiation, systemic radiation). With internal radiation, a high dose of radiation is given inside the body as close to the cancer as possible. The radiation treatment may be swallowed, injected, or implanted directly into the tumor. Some of the radioactive implants are called seeds or capsules. Internal radiation involves administering a higher dose of radiation in a shorter time span when compared with external radiation. Some internal radiation treatments stay in the body temporarily; other internal treatments stay in the body permanently, although the radioactive substance loses its radiation energy over time. In some cases, both internal and external radiation therapies are used.
New delivery methods for radiation therapy are under investigation.
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