Dictionary

ragweed Any of several weedy composite herbs that produce a pollen to which many people are allergic. Of all allergy sufferers in the US, 75 percent are allergic to ragweed.

Raeder syndrome See cluster headache.

radon A radioactive element that is formed, as a gas, during the breakdown of radium. Radon exposure is the second leading cause of lung cancer deaths in the United States, after smoking. Radon gas continuously seeps into the air from uraniumand radium-bearing soil and rock. Well water can be contaminated with radon and may carry…

radius The smaller of the two bones of the forearm, located on the thumb’s side. (The larger bone in the forearm is the ulna.)

radium The radioactive element discovered by Marie and Pierre Curie in 1898. Since the discovery of radium, many radioactive isotopes have been used for both the diagnosis and the treatment of diseases.

radiotherapy See radiation therapy.

radiosensitive Sensitive to X-rays and other forms of radiant energy. For example, if a tumor is radiosensitive, it is potentially treatable with radiation therapy. The opposite of radiosensitive is radioinsensitive.

radiopaque Opaque to one or another form of radiation, such as X-rays. Radiopaque objects block radiation rather than allow it to pass through. Metal, for instance, is radiopaque, so metal objects that a patient may have swallowed are visible on X-rays. Radiopaque dyes are used in radiology to enhance X-ray pictures of internal anatomic structures….

radionuclide scan An exam that produces pictures (scans) of internal parts of the body based upon the presence of radioactive material. The patient is administered a small amount of radioactive material. A machine called a scanner then measures the radioactivity in certain organs.

radiolucent Permeable to one or another form of radiation, such as X-rays. Radiolucent objects do not block radiation but let it pass. Plastic is usually radiolucent. The opposite of radiolucent is radiopaque.

radiology, interventional The use of image guidance methods to gain access to the deepest interior of most organs and organ systems. Interventional radiology includes the use of balloons, catheters, microcatheters, stents, therapeutic embolization (deliberately clogging up a blood vessel), and more. The specialty of interventional radiology overlaps with other surgical arenas, including interventional cardiology, vascular…

radiology The medical specialty concerned with radiation for the diagnosis and treatment of disease, including both ionizing radiation such as X-rays and nonionizing radiation such as ultrasound. Also known as roentgenology.