Medical terms - Letter R (page 2) | MedicalVocabulary.org

Radioactive iodine

An isotope of the chemical element iodine that is radioactive. Radioactive iodine is used in diagnostic tests as well as in radiotherapy of an hyperactive thyroid gland (hyperthyroidism), most often due to Graves…
Radioactive tracer

A radioactive molecule that can be sent through the body's circulatory or urinary system, with its progress followed by a radiation-sensitive machine
Radioallergosorbent test

An allergy test done on a sample of blood. The test is used to check for allergic sensitivity to specific substances. In the test, the sample of blood is mixed with substances known to trigger allergies. The test…
Radiofrequency ablation

Radiofrequency ablation: The use of electrodes to generate heat and destroy abnormal tissue. In radiofrequency ablation (RFA), heat is generated locally by a high frequency, alternating current that flows from the…
Radiograph

A film with an image of body tissues that was produced when the body was placed adjacent to the film while radiating with X-rays
Radiography

Film records (radiographs) of internal structures of the body. Radiography is made possible by X-rays (or gamma rays) passing through the body to act on a specially sensitized film
Radioimmunoassay

A very sensitive, specific laboratory test (assay) using radiolabeled (and unlabeled) substances in an immunological (antibody-antigen) reaction
Radioinsensitive

Not sensitive to X-rays and other forms of radiant energy. For example, a tumor may be radioinsensitive, and therefore cannot be successfully attacked using radiation therapy. The opposite of radiosensitive
Radioiodine

An isotope of the chemical element iodine that is radioactive. Radioiodine is used in diagnostic tests as well as in radiotherapy of an hyperactive thyroid gland (hyperthyroidism), most often due to Graves disease. For…
Radioisotope

A version of a chemical element that has an unstable nucleus and emits radiation during its decay to a stable form. Radioisotopes have important uses in medical diagnosis, treatment, and research. A radioisotope is…
Radiologic

Having to do with radiology.
Radiologist

A physician specialized in radiology, the branch of medicine that uses ionizing and nonionizing radiation for the diagnosis and treatment of disease. Like other physicians, a radiologist must have graduated from an…
Radiology

The branch of medicine that uses ionizing and nonionizing radiation for the diagnosis and treatment of disease. Historically, radiology involved the use of ionizing radiation including X rays for the diagnosis of…
Radiology, interventional

The use of image guidance methods to gain access to the deepest interior of most organs and organ systems. Through a galaxy of techniques, interventional radiologists can treat certain conditions through the skin…
Radiolucent

Anything that permits the penetration and passage of X-rays or other forms of radiation. Radiolucent is as opposed to radiopaque (which refers to anything that blocks the penetration of X-rays). Plastic is usually…
Radiomimetic

Imitating radiation. A radiomimetic drug is one that imitates the effects of radiation as in the case of chemicals such as nitrogen mustards which are used in cancer chemotherapy. The 'mimetic' part of 'radiomimetic'…
Radionuclide

An unstable form of a chemical element that radioactively decays, resulting in the emission of nuclear radiation. Also called a radioisotope
Radionuclide scan

An examination that produces pictures of internal parts of the body. The patient is given an injection or swallows a small amount of radioactive material (a radionuclide). A scanner machine then measures the…
Radionuclide stress test

A procedure that involves injecting a radioactive isotope, typically thallium or cardiolyte, into the patient's vein after which an image of the patient's heart becomes visible with a special camera. The radioactive…
Radiopaque

Anything that does not let X-rays or other types of radiation penetrate. Radiopaque objects block radiation. They are opaque to radiation. A metal object, for example, is typically radiopaque. If a child swallows a coin…
Radiosensitive

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

The treatment of disease with ionizing radiation. Also called radiation therapy. In radiotherapy, high-energy rays are often used to damage cancer cells and stop them from growing and dividing. A specialist in the…
Radiotherapy, stereotactic

Radiation therapy in which a number of precisely aimed beams of ionizing radiation coming from different directions meet at a specific point, delivering the radiation treatment to that spot
Radium

The celebrated radioactive element discovered by Marie and Pierre Curie in 1898
Radius

In anatomy, the radius is the smaller of the two bones on the thumb side of the forearm. (The bigger one is the ulna). The word 'radius' comes unchanged from the Latin meaning a spoke in a wheel which this bone was…
Radon

A radioactive element formed as a gas during the breakdown of radium.
Raeder's syndrome

A distinctive syndrome of headaches, also known as cluster headache or migrainous neuralgia. The common pattern of cluster headache is termed 'episodic' and is characterized by 1-3 short attacks of pain each day around…
Ragged red fibers with CPEO

See: Kearns-Sayre syndrome
Ragweed

Any of a number of weedy composite herbs that produce a pollen that is a frequent cause of allergies. Of all allergy sufferers in the United States, 75% are allergic to ragweed
Raised hemidiaphragm

See: Elevated hemidiaphragm.
Rale

A type of abnormal lung sound heard through a stethoscope. Rales may be sibilant (whistling), dry (crackling) or wet (more sloshy) depending on the amount and density of fluid refluxing back and forth in the air…
Ramsay Hunt syndrome

Ramsay Hunt syndrome: A herpes virus infection of the geniculate nerve ganglion that causes paralysis of the facial muscles on the same side of the face as the infection. The geniculate ganglion is a sensory ganglion…
Ramsay Hunt, James

Pre-eminent 20th-century American neurologist (1872-1937) who described a number of important diseases. Including: > >Ramsay Hunt paralysis: An hereditary disorder resembling adult Parkinson's disease, but less severe…
Ramus

In anatomy, a branch, such as a branch of a blood vessel or nerve. For example, the ramus acetabularis arteriae circumflexae femoris medialis is the branch of an artery that goes to the socket of the hip joint. The…
Ramus of the mandible

One of the two prominent, projecting back parts of the horseshoe-shaped lower jaw bone
Random

The process by which an outcome is determined solely by chance, for example, by a coin flip. A randomized controlled trial is a clinical trial that involves at least one test treatment and one control treatment and in…
Random mating

Totally haphazard mating with no regard to the genetic makeup (genotype) of the mate so that any sperm has an equal chance of fertilizing any egg. This rarely, if ever, occurs but the concept is important in population…
Random number table

A table of numbers generated in an unpredictable, haphazard sequence. Tables of random numbers are used to create a random sample. A random number table is therefore also called a random sample table. Random numbers…
Random numbers

Numbers generated in an unpredictable haphazard sequence; numbers generated by chance alone
Random sample

A group selected randomly, solely by chance
Randomization

A method based on chance alone by which study participants are assigned to a treatment group. Randomization minimizes the differences among groups by equally distributing people with particular characteristics among all…
Randomize

To use chance alone to assign or arrange. For example, the investigators may randomize the participants in a clinical trial to different groups in order to compare the outcomes of different treatments
Randomized

The use of chance alone to assign the participants in an experiment or trial to different groups in order to fairly compare the outcomes with different treatments. Randomization is an important feature of experimental…
Randomized clinical trial

A clinical trial in which the participants are assigned randomly (by chance alone) to different treatments. See also: Randomized controlled trial
Randomized controlled trial

(RCT) A study in which people are allocated at random (by chance alone) to receive one of several clinical interventions. One of these interventions is the standard of comparison or control. The control may be a…
Randomly

In a random manner, as by chance alone. The participants in the trial were randomly assigned to receive aspirin or a placebo
Range

In medicine and statistics, the difference between the lowest and highest numerical values. For example, if five premature infants are born weighing two, three, four, four, and five pounds respectively, the range of…
Range of motion

The range through which a joint can be moved, usually its range of flexion and extension. Due to an injury, the knee may for example lack 10 degrees of full extension
Range, normal

By convention, the normal range for whatever (a particular test, condition, symptom, behavior, etc.) is set to cover ninety-five percent (95%) of all values from the general population. Five percent (5%) of results…
RANTES

A cytokine that is a member of the interleukin-8 superfamily of cytokines. RANTES is a protein. It is a selective attractant for memory T lymphocytes and monocytes. It binds to CCR5, a coreceptor of HIV. RANTES is an…