<b>Don't be afraid to ask your health care staff to explain any terms you don't understand.</b> 

<b>Adjuvant therapy</b> Treatment added to the primary treatment to enhance the effectiveness of the primary treatment. Radiation therapy often is used as an adjuvant to surgery. 
<b>Alopecia</b> (al-oh-PEE-she-ah) Hair loss. 
<b>Anesthesia</b> Loss of feeling or sensation to prevent pain. Certain drugs or gases called 'anesthetics' are used to achieve anesthesia so that medical procedures may be performed without pain. A local anesthetic causes loss of feeling in part of the body. A general anesthetic puts the patient to sleep. 
<b>Antiemetic</b> (an-tee-eh-MET-ik) A medicine that prevents or relieves nausea and vomiting. 
<b>Biological therapy</b> Treatment to stimulate or restore the ability of the immune system to fight infection and disease; also called immunotherapy. 
<b>Brachytherapy</b> (BRAK-ee-THER-ah-pee) Internal radiation therapy using an implant of radioactive material placed directly into or near the tumor; also called "internal radiation therapy." 
<b>Cancer</b> A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread through the bloodstream and lymphatic system to other parts of the body. 
<b>Catheter</b> A thin, flexible, hollow tube through which fluids enter or leave the body. Radioactive materials may be placed in catheters that are placed near the cancer. 
<b>Chemotherapy</b> Treatment with anticancer drugs. 
<b>Cobalt 60</b> A radioactive substance used as a radiation source to treat cancer. 
<b>CT (computed tomography) scan</b> An x-ray procedure that uses a computer to produce a series of detailed pictures of a cross section of the body; also called a CAT scan. 
<b>Dietitian</b> (also "registered dietitian") A professional who plans diet programs for proper nutrition. 
<b>Dosimetrist</b> (do-SIM-uh-trist) A person who plans and calculates the proper radiation dose for treatment. 
<b>Electron beam</b> A stream of electrons (small negatively charged particles found in atoms) that can be used for radiation therapy. 
<b>External radiation</b> The use of radiation from a machine located outside of the body to aim high-energy rays at cancer cells. 
<b>Fluoride</b> A chemical applied to the teeth to prevent tooth decay. 
<b>Gamma knife</b> Radiation therapy in which high energy rays are aimed at a brain tumor from many angles in a single treatment session. 
<b>Gamma rays</b> High-energy rays that come from a radioactive source such as cobalt-60. 
<b>High dose-rate remote brachytherapy</b> A type of internal radiation treatment in which the radioactive source is removed between treatments; also known as 'high dose-rate remote radiation therapy.' 
<b>Hyperfractionated radiation</b> Radiation treatment that is given in smaller-than-usual doses two or three times a day. 
<b>Implant</b> A radioactive source in a small holder that is placed in the body in or near a cancer. 
<b>Internal radiation</b> Radiation therapy that uses the technique of placing a radioactive source in or near a cancer. 
<b>Interstitial radiation</b> A radioactive source (implant) placed directly into the cancerous tissue such as the head and neck region or the breast. 
<b>Intracavitary radiation</b> A radioactive source (implant) placed in a body cavity such as the chest cavity or the vagina. 
<b>Intraoperative radiation</b> External radiation treatment given during surgery to deliver a large dose of radiation to the tumor bed and surrounding tissue; also called IORT. 
<b>Linear accelerator</b> A machine that creates high-energy radiation to treat cancers, using electricity to form a stream of fast-moving subatomic particles; also called 'mega-voltage (MeV) linear accelerator' or a "linac." 
<b>Lumen</b> The cavity or channel within a tube or tubular organ such as a blood vessel or the intestine. 
<b>Medical oncologist</b> A doctor who specializes in treating cancer with chemotherapy. 
<b>Neutron</b> A small, uncharged particle of matter found in the atoms of all elements except hydrogen. Streams of neutrons generated by special equipment can be used for radiation treatment. 
<b>Oncologist</b> A doctor who specializes in treating cancer. 
<b>Palliative care, palliation</b> Treatment that relieves symptoms but does not cure disease. Palliative care can help people with cancer live more comfortably. 
<b>Physical therapist</b> A health professional trained in the use of treatments such as exercise and massage. 
<b>Platelets</b> Blood cells that help stop bleeding by contributing to the formation of clots. 
<b>Prosthesis</b> An artificial replacement for a body part. 
<b>Proton</b> A small, positively charged particle of matter found in the atoms of all elements. Streams of protons generated by special equipment can be used for radiation treatment. 
<b>Radiation</b> Energy carried by waves or a stream of particles. 
<b>Radiation nurse</b> A nurse who specializes in caring for people who are undergoing radiation therapy. 
<b>Radiation oncologist</b> A doctor who specializes in treating cancer with radiation. 
<b>Radiation physicist</b> The person who makes sure that the radiation machine delivers the right 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. 
<b>Radiation therapist</b> The person who runs the equipment that delivers the radiation. 
<b>Radiation therapy</b> 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.) 
<b>Radioactive</b> Capable of emitting high-energy rays or particles. 
<b>Radiologist</b> A doctor with special training in creating and interpreting pictures of areas inside the body. The pictures are produced with x-rays, sound waves, or other types of energy. 
<b>Reconstructive surgery</b> Surgical procedure done to restore the shape of an area of the body altered by cancer surgery. 
<b>Recurrent</b> Reappearance of cancer cells at the same site or in another location after a disease-free period. 
<b>Red blood cells</b> Cells that carry oxygen to all parts of the body. Also called "erythrocytes." 
<b>Remote brachytherapy</b> See "high dose-rate remote brachytherapy." 
<b>Simulation</b> The process used to plan radiation therapy so that the target area is precisely located and marked. 
<b>Telangiectasia</b> A skin lesion that results from dilation of a group of small blood vessels. 
<b>Treatment port or treatment field</b> The place on the body at which the radiation beam is aimed. 
<b>Tumor</b> An abnormal mass 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). 
<b>Unsealed internal radiation therapy</b> Internal radiation therapy given by injecting a radioactive substance into the bloodstream or a body cavity. This substance is not sealed in a container. 
<b>White blood cells</b> Cells that help the body fight infection and disease. 
<b>X-rays</b> High-energy radiation that is used in low doses to diagnose disease and in high doses to treat cancer. 

Most of this Glossary comes from &&url, an NCI publication, available on the National Cancer Institute Website. 