Radiology and Nuclear Medicine

computed tomography (CT)

Diagnostic x-ray procedure whereby a cross-sectional image of a specific body segment is produced.

contrast studies

Radiopaque materials (contrast media) are injected to obtain contrast between tissues that would be indistinguishable from one another.

gamma camera

Machine to detect gamma rays emitted from radiopharmaceuticals during scanning for diagnostic purposes.

gamma rays

High-energy rays emitted by radioactive substances used in tracer studies.

half-life

Time required for a radioactive substance to lose half its radioactivity by disintegration.

interventional radiology

Therapeutic or diagnostic procedures performed by a radiologist. Examples are needle biopsy of a mass and drainage of an abscess, typically under the guidance of CT, ultrasound, or fluoroscopy.

in vitro

Process, test, or procedure is performed, measured, or observed outside a living organism, often in a test tube.

in vivo

Process, test, or procedure is performed, measured, or observed within a living organism.

ionization

Transformation of electrically neutral substances into electrically charged particles.

magnetic resonance imaging (MRI)

Magnetic field and radio waves produce sagittal, coronal, and axial images of the body.

nuclear medicine

Medical specialty that uses radioactive substances (radionuclides) in the diagnosis and treatment of disease.

positron emmission tomography (PET)

Positron-emitting radioactive substances given intravenously create a cross-sectional image of cellular metabolism based on local concentration of the radioactive substance.

radioimmunoassay

Test combines radioactive chemicals and antibodies to detect minute quantities of substances in a patient’s blood.

radioisotope

Radioactive form of an element substance; radionuclide.

radiolabeled compound

Radiopharmaceutical; used in nuclear medicine studies.

radiology

Medical specialty concerned with the study of x-rays and their use in the diagnosis of disease. It includes other forms of energy, such as ultrasound and magnetic waves.

radiolucent

Permitting the passage of x-rays.

radionuclide

Radioactive form of an element that gives off energy in the form of radiation; radioisotope.

radiopaque

Obstructing the passage of x-rays.

radiopharmaceutical

Radioactive drug (radionuclide plus chemical) that is administered safely for diagnostic and therapeutic purposes;

scan

Image of an area, organ, or tissue of the body obtained from ultrasonography, radioactive tracer studies, computed tomography, or magnetic resonance imaging.

scintigraphy

Diagnostic nuclear medicine test using radiopharmaceuticals and gamma cameras to create images.

single photon emission computed tomography (SPECT)

Radioactive tracer is injected intravenously and a computer reconstructs a 3D image based on a composite of many views.

tagging

Attaching a radionuclide to a chemical and following its path in the body.

tracer studies

Radionuclides are used as tags, or labels, attached to chemicals and followed as they travel through the body.

ultrasonography (US, U/S)

Diagnostic technique that uses high-frequency sound waves to produce images of the body.

ultrasound transducer

Handheld device that sends and receives ultrasound signals.

uptake

Rate of absorption of a radionuclide into an organ or tissue.

ventilation-perfusion study (V/Q scan)

Consists of two scans: a ventilation scan performed using an inhaled radiopharmaceutical and a perfusion scan using an intravenously injected radiopharmaceutical. Used to evaluate for pulmonary embolism.