rad - The unit for the dose absorbed from ionizing radiation, equivalent to 100 ergs per gram of tissue; 100 rad = 1 Gy. , Symbol for radian. , Abbreviation for racemic., -

radiation - (rA-dE-A-shun) - The act or condition of diverging in all directions from a center. , The sending forth of light, short radio waves, ultraviolet or xrays, or any other rays for treatment or diagnosis or for other purpose. , Radiant energy from waves or subatomic particles., -

radiation dermatosis - Skin changes at the site of ionizing radiation, particularly redness of the skin due to capillary dilatation in the acute stage, temporary or permanent loss of hair, and chronic changes in the epidermis and dermis resembling a premalignant warty lesion. -

radiation oncologist - Radiation oncologists are the doctors who oversee the care of each cancer patient undergoing radiation treatment. They develop and prescribe each cancer patient's treatment plan. They make sure that every treatment is accurately given. They monitor the patient's progress and adjust treatment to make sure patients get quality care throughout treatment. Radiation oncologists also help identify and treat any side effects of radiation therapy. They work closely with other physicians, and all members of the radiation oncology team. Radiation oncologists have completed four years of college, four years of medical school, one year of general medical training, then four years of residency (specialty) training in radiation oncology. They have extensive training in the safe use of radiation to treat disease. If they pass a special examination, they are certified by the American Board of Radiology. Patients should ask if their doctor is board certified. -

radiation oncology - The medical specialty of radiation therapy; the study of radiation treatment of abnormal tissue growths (malignant or nonmalignant). -

radiation oncology nurses - Nurses work with the radiation team to care for patients during the course of treatment. They help evaluate the patient before treatment begins. They may talk to the patient about potential side effects and their management. During the course of radiation treatments patients may be evaluated weekly, or more frequently by the nurse to assess problems and concerns. Nurses play a key role in educating the patient about treatment, side effects, etc. Radiation oncology nurses are registered nurses licensed to practice professional nursing. Most nurses in radiation therapy have additional accreditation in the specialty of oncology nursing. Advanced practice nurses in oncology, which include clinical nurse specialists and nurse practitioners, have completed a master's degree program. -

radiation Physicist - A person who makes sure that the radiation machine or implant delivers the right amount of radiation to the correct site in the body. The physicist works with the radiation oncologist to choose the treatment schedule and dose that has the best chance of killing the most cancer cells. -

radiation pneumonitis - Inflammation of lung tissue caused by exposure to radiation therapy. -

radiation therapist - Radiation therapists work with radiation oncologists. They administer the daily radiation treatment under the doctor's prescription and supervision. They maintain daily records and regularly check the treatment machines to make sure they are working properly. Radiation therapists go through a two-to-four year educational program following high school or college. They take a special examination and must be certified by the American Registry of Radiologic Technologists. In addition, many states require that radiation therapists be licensed.

radiation Therapy - Also called radiotherapy or irradiation, it is the careful use of various forms of radiation to treat cancer and other diseases. Treatment for non-malignant conditions and/or cancer through the use of xrays or radionuclides.

radiation Units - There are a number of units to measure radiation dose and exposure: rad or radiation absorbed dose -

radioactive - Giving off radiation. -

radioactive disintegration - The decrease in the amount of any radioactive material with the passage of time due to the spontaneous emission of radiation from an atomic nucleus. -

radioactive iodine I -131 therapy - radioactive iodine I-131 therapy. The use of radioactive iodine I-131 to treat an overactive thyroid, a condition called hyperthyroidism. When a small amount of I-131 is swallowed, it is absorbed into the bloodstream in the gastrointestinal (GI) tract and concentrated from the blood by the thyroid gland, where it begins destroying the gland’s cells. -

radioactive iodine uptake test (RAIU) - See thyroid uptake. -

radioactive material - Also called radioactive substance. -

radioactive substance - See radioactive material. -

radiodense markers - Small pieces of radiodense, or radiopaque, material placed inside the body near a tumor to help the treatment team direct radiation beams at the cancerous cells. Radiodense markers are made from materials that cannot be penetrated by xrays or any other form of radiation.

radiofrequency ablation - A treatment technique that uses high-frequency alternating electrical current to destroy tissue cells by heating them.

radiofrequency electrodes - An electrode is a fine wire through which electrical current may flow in or out when attached to a power source. A radiofrequency electrode carries high frequency electromagnetic waves that creates heat to ablate or destroy tissue (called radiofrequency ablation) or to seal blood vessels. -

radiographic - (rA-dE-agrafic) - Referring to the examination of any part of the body for diagnostic purposes by means of xrays or other diagnostic modalities.

radiography - (rA-dE-agraf-E) - Examination of any part of the body for diagnostic purposes by means of xrays with the record of the findings usually impressed upon a photographic film.

radioimmunotherapy - The use of radiolabeled antibodies to deliver radiation directly to a tumor. -

radioiodine I -131- See radioactive iodine I-131

radioisotope - (rA-dE-Oi-sO-tOp) - An isotope that changes to a more stable state by emitting radiation.

radioisotope bone scan - A nuclear imaging examination that produces pictures of bones to help detect abnormalities caused by disease or injury. During a bone scan, a small amount of radioactive material is injected into the body and collects in the bones. -

radiolabeled Antibodies - Monoclonal antibodies that have had a radioactive isotope attached to them in a process called radiolabeling. These antibodies are designed to attach themselves directly to diseased cells and damage them with small amounts of radiation without hurting nearby healthy cells. -

radiologist - (rA-dE-Ol-O-jist) - A physician trained in the diagnostic and/or therapeutic use of xrays and radionuclides, radiation physics, and biology; a diagnostic radiologist may also be trained in diagnostic ultrasound and magnetic resonance imaging and applicable physics.

radiology - (rA-dE-ol-O-jE) - The science of high energy radiation and of the sources and the chemical, physical, and biologic effects of such radiation; the term usually refers to the diagnosis and treatment of disease. , The scientific discipline of medical imaging using ionizing radiation, radionuclides, nuclear magnetic resonance, and ultrasound. , -

radiology Information System (RIS) - A special case of a hospital information system (HIS) tailored to radiological imaging, containing information such as imaging examination orders, schedules on imaging modalities, imaging device parameters, billing codes and information. -

radionuclide - (rA-dE-O-nU-klId) - An isotope of artificial or natural origin that exhibits radioactivity. -

radiopaque - (rA-dE-O-pAK) - Impenetrable by xrays or any other form of radiation. -

radiopaque dye - (rA-dE-O-pAK dI) - See contrast material. -

radiopharmaceutical - A drug that emits radioactivity. Also called a radiotracer. -

radioprotector - A type of drug that protects normal tissues in the area being treated. -

radioresistant - A term used to describe a tumor that does not respond well to radiation therapy. -

radiosensitizer - A type of drug that can make a tumor respond better to radiation therapy. -

radiosensitizers - Drugs that enhance the effect of radiation on cancer cells. -

radiosurgery - A technique that allows your radiation oncologist to precisely focus beams of radiation to destroy certain types of tumors. It is most often called stereotactic radiotherapy. -

radiotherapists - (rA-dE-O-thar-a-pist) - One who practices radiotherapy or is versed in radiotherapeutics.

radiotherapy - Also called radiation therapy or irradiation, it is the careful use of various forms of radiation to treat cancer and other diseases. -

radiotracer - See radiopharmaceutical. -

reactive airway disease - An asthma-like syndrome that can cause wheezing, chest tightness, coughing and difficulty breathing. This includes patients with asthma.

rectum - The lower part of the large intestine where feces are stored. -

referring physician - Usually a family physician who sends a patient to a specialist for more information or treatment. -

regional anesthesia - The injection of a local anesthetic, a medication that produce a temporary loss of sensation, near a specific group of nerves in order to block sensation in a larger, but still limited, area of the body supplied by those nerves. -

regional enteritis (Crohn's disease) - See Crohn's disease. -

renal artery - (rE-nal ar-ter-E) - The major artery supplying the kidney. -

renal hypertension - When the renal arteries are narrowed by atherosclerosis, not enough blood reaches the kidney tissue and, as a result, substances are released that raise the blood pressure. -

reproductive - Relating to the system of organs and parts used in reproduction consisting in the male especially of the testes, penis, seminal vesicles, prostate, and urethra and in the female especially of the ovaries, fallopian tubes, uterus, vagina, and vulva. -

resection - Surgical removal of part or all of an organ or an area of diseased tissue. -

respiratory - Related to the process of moving air into and out of the lungs, exchanging oxygen and carbon dioxide within the body's tissues. Also called pulmonary ventilation. -

restenosis - The gradual re-closing of an artery after it has been widened through a procedure such as angioplasty.

retinoblastoma - A tumor of the retina, occurring in children. -

roentgen (R, r) - (rentgen, rent-chen) - The international unit of exposure dose for xrays or gamma rays; that quantity of radiation that will produce in 1 cm of air at STP, or 0.001293 g of air, 2.08 ×109 ions of both signs, each totaling 1 electrostatic unit (e.s.u.) of charge; in the MKS system this is 2.58 ×10-4 coulombs per kg of air. -