Radiation Therapy

Radiation Therapy: Glossary

Here are definitions of medical terms related to radiation therapy.

Adjuvant: Using therapies such as surgery, chemotherapy or radiation therapy in combination to achieve more effective results than using a treatment alone.

Anesthesia: Loss of feeling or sensation to prevent pain so that surgery or other procedures can take place. A local anesthetic causes loss of feeling in a part of the body, while a general anesthetic puts the patient to sleep.

Antiemetics: Drugs that prevent or relieve nausea and vomiting.

Brachytherapy: A form of radiation therapy that places radioactive substances in direct contact with the tissue being treated.

Cancer: Diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread through the blood stream and lymphatic system to other parts of the body.

Catheter: A thin, flexible, hollow surgical tube used to put fluids into or take fluids out of the body. Catheters are sometimes used to place radioactive materials near cancerous tissue.

Chemotherapy: Treating cancer with drugs that are given by mouth or intravenously. Can be used alone or in combination with surgery and/or radiation therapy or other treatments.

Cobalt: A radioactive substance used as a radiation source to treat cancer.

Dietitian (also “registered dietitian”): A health professional who advises patients about nutrition and plans proper diets.

Dosimetrist: A person who plans and calculates the proper radiation dose for treatment.

Gamma rays: Powerful and penetrating rays that can be used in radiation therapy to kill cancer cells.

Electron beam: A stream of electrons (small negatively charged particles found in atoms) that are used for radiation therapy.

External radiation: Using radiation from a machine that aims high-energy rays at cancer cells.

Fractionated radiation: Radiation treatment that is given in smaller-than-usual doses two or more times a day.

Implant: Also called a “seed,” it is the combination of a the radioactive source placed in a small holder that is inserted in the body in or near a cancer.

Internal radiation: Radiation therapy that uses the technique of placing a radioactive source in or near a cancer.

Interstitial radiation: A radioactive source (implant) placed directly into the cancerous tissue such as the head and neck region or the breast. Also called brachytherapy.

Intracavitary radiation: A radioactive source (implant) placed in a body cavity such as the chest cavity or the vagina.

Medical oncologist: A doctor who specializes in treating cancer with chemotherapy, hormones, and biotherapy, and often oversees the total care a cancer patient receives.

Medical radiation physicist: A person who makes sure the radiation machine delivers the exact amount of radiation to the treatment site. In consultation with the radiation oncologist, the physicist also determines the treatment schedule that will have the best chance of killing the most cancer cells.

Oncologist: A doctor who specializes in treating cancer.

Palliative care, palliation: Treatment that relieves symptoms and pain but does not cure disease. Palliative care can help people with cancer live more comfortably.

Primary treatment: The treatment used first or alone to treat cancer.

Radiation: Electromagnetic energy carried by waves or a stream of particles.

Radiation nurse: A nurse who specializes in caring for people undergoing radiation therapy.

Radiation oncologist: A doctor who specializes in treating cancer with radiation.

Radiation therapist: A person who runs the equipment that delivers the radiation.

Radiation therapy: Also known as radiation therapy, x-ray therapy, radiotherapy, or irradiation. Treatment with high-energy rays (such as x-rays) to kill cancer cells. The radiation may come from outside of the body (external radiation) or from radioactive materials placed directly in the tumor (internal or implant radiation). Types of radiation include x-rays, electron beams, gamma rays, neutron beams, and proton beams. Radioactive substances include cobalt, iridium, and cesium. (See also gamma rays, brachytherapy, and x-ray.)

Radioactive: Capable of emitting high-energy rays or particles.

Radiologist: A doctor with special training in using and interpreting images of areas inside the body to diagnose and treat diseases. The images are produced with x-rays, sound waves, or other types of energy.

Recurrent: Reappearance of cancer cells at the same site or in another location after a disease-free period.

Red blood cells: Cells in the blood that carry oxygen to cells throughout the body. Also called “erythrocytes.”

Simulation: The process used to plan radiation therapy so that the target area is precisely located and marked.

Treatment port or treatment field: The place on the body at which the radiation beam is aimed.

Tumor: An abnormal growth of excess tissue that results from excessive cell division. Tumors perform no useful body function and may be either benign (not cancerous) or malignant (cancerous).

White blood cells: Cells that circulate in the blood and the lymph system that help fight infection and disease. They are a part of the immune system.

X-rays: High-energy penetrating radiation used in low doses to diagnose disease and in high doses to treat cancer.