Radiation therapy (also called radiotherapy, therapeutic radiology or radiation oncology) uses X-rays, gamma rays, and charged particles to fight cancer. Like surgery, radiation therapy can be used in several ways depending on the type and location of the cancer. Certain levels of radiation work to kill cancer cells or prevent cells from growing or reproducing. This treatment may provide a cure for cancer, help control the disease, or help relieve its symptoms. Most radiation treatments are delivered from a machine outside the body and won't make you radioactive. Less often, a source of radiation may be put into your body for a short time. Talk with your healthcare provider about any safety measures you should take when getting radiation therapy.
Radiation therapy is given through different methods. The method will depend on the type of cancer, the location of the cancer, and your health. Sometimes radiation therapy is used with other treatments. Different types of radiation therapy include:
External radiation (external beam therapy). The treatment is given with a large machine that points the radiation beams directly at the tumor. The beams are often aimed at the tumor from many different angles. A radiation therapist controls the machine. Since radiation can also affect nearby normal cells, special shields may be made to protect the tissue surrounding the treatment area. Often, more than 1 treatment is given. Radiation treatments are painless and usually last a few minutes.
Internal radiation (brachytherapy, implant radiation, systemic radiation). A high dose of radiation is given inside the body. This is typically done as close to the cancer as possible. The radiation source may be swallowed, injected, implanted directly into the tumor, or put next to the tumor through a body opening (such as the rectum). Some of the radioactive implants are called seeds or capsules. Internal radiation typically involves getting a higher dose of radiation over a shorter time when compared with external radiation. Some sources of internal radiation stay in the body for a short time (temporarily). Others stay in the body forever (permanently), but they lose their radiation energy over time.
In some cases, both internal and external radiation therapies are used.
New delivery methods for radiation therapy are under investigation.
Radiation should be aimed as precisely at the tumor as possible. This is important for treating the tumor. It’s also important for preventing nearby normal tissues from getting too much radiation, which could lead to side effects. Although each hospital may have certain protocols, radiation therapy usually begins with these procedures:
Simulation process. After a physical exam and a review of your medical history, your treatment team maps out the position you will be in for each treatment and the exact place on your body (the 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, a doctor called a radiation oncologist will determine your treatment plan. This will include the type of machine to use, the amount (dose) of radiation that is needed, and the number of treatments you will be given.
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