Radiation Therapy for Cancer Treatment

Radiation therapy (also called therapeutic radiology or radiation oncology) uses special kinds of energy waves or 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.

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 a treatment field or port) where the radiation will be given (the simulation process). 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 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 of radiation that is needed, and the number of treatments that will be given.

What are the different types of radiation therapy?

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 Radiation Therapy)

  With external radiation (external beam radiation therapy), radiation is administered by a large machine that points the energy waves directly at the tumor. The radiation therapist controls the machine. Because radiation is used to kill cancer cells, special shields may be used to protect the tissue surrounding the treatment area. Radiation treatments are painless and usually last a few minutes.
  
  External radiation techniques have been developed to increase the likelihood that the radiation dose given will kill targeted cancer cells instead of affecting surrounding tissue. This increases the effect of radiation while decreasing its adverse effects. These techniques are carried out using modern medical imaging techniques and computer control over the radiation beam. They include three-dimensional conformal radiation therapy, intensity-modulated radiation therapy, image-guided radiation therapy, and radio-"surgery."
  

• Internal Radiation (Brachytherapy, Implant Radiation)

  With internal radiation (brachytherapy, implant 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 within a short period of time. In some cases, both internal and external radiation therapies are used.

• Systemic Radiation
  
  In systemic radiation, radioactive substances are swallowed or injected so that they may be taken up by the cancerous tissue internally, or travel with the circulation. This is effective for certain types of cancer. It can only be performed with substances especially prepared for this use, with appropriate precautions.