Radiation is known by many names: radiotherapy, irradiation and X-ray therapy. Regardless of what you call it, its purpose is still the same--to destroy cancer cells and make it impossible for them to grow and divide. The type of radiation therapy chosen to treat a patient's cancer depends on the type and severity of the cancer and how deep the radiation needs to penetrate the body.
External Radiation
External radiation is performed on an outpatient basis, and the radiation may come from a variety of sources, such as X-rays, gamma rays or an electron beam. A machine is used to deliver the radiation, directing it specifically at the site of the cancer to ensure minimal damage to the healthy tissues surrounding it. A number of factors are used to determine the dose of radiation and the number of treatments needed. These include the type of cancer, the size and location of the tumor, the patient's overall health and any other treatments the patient may be receiving.
Internal Radiation
Internal radiation allows a doctor to place the source of radiation as close to the cancer cells as possible. This ensures that the fewest number of healthy cells are affected during treatment, while allowing the doctor to deliver higher doses of radiation in a shorter period of time. The radioactive material is typically placed in plastic tubes or containers, such as catheters, or may be in the form of seeds. These containers are implanted into the tumor itself or as close to it as possible. In some cases, an applicator is required to hold the implant in place; this may cause discomfort, in which case the patient may be given medication to help relieve the pain.
On occasion, the substances implanted can emit radioactive rays outside of the body; for this reason, the patient needs to be admitted to the hospital to receive internal radiation and stay in a private room until treatment is complete. According to St. Vincent Health, the dose determines how long the implant remains in the body. Low-dose internal radiation treatment can last between one and seven days.
Intensity-Modulated Radiation
Intensity-modulated radiation therapy (IMRT) is considered an advanced type of radiation therapy, according to RadiologyInfo.com. It allows for both higher and more effective doses of radiation to be delivered to a tumor, reducing both treatment toxicity and side effects.
The radiation is delivered using a three-dimensional image of the tumor. This helps the radiation oncologist (doctor) deliver the radiation more precisely to specific areas of the tumor, controlling the dose with a computer. Delivery of radiation in this manner allows him to direct intense beams in multiple, small volumes. IMRT is used most frequently to treat cancer located in the head, prostate and neck.
