Bma Illustrated Medical Dictionary

radiculopathyDamage to the nerve

roots that enter or leave the spinal cord.

Radiculopathy may be caused by disc

prolapse, spinalarthritis, diabetes mellitus,

or ingestion of heavy metals such as lead.

The symptoms are severe pain and,

occasionally, loss of feeling in the area

supplied by the affected nerves, and

weakness, paralysis, and wasting of

muscles supplied by the nerves. If pos-

sible, the underlying cause is treated;

otherwise, symptoms may be relieved

by analgesic drugs, physiotherapy, or, in

some cases, surgery.

radioactivityThe emission of alpha

particles, beta particles, and/or gamma

radiation that occurs when the nuclei of

unstable atoms spontaneously disinte-

grate. Many radioactive substances are

naturally occurring – for example, ura-

nium ores. (See also radiation.)

radiographyThe use of radiation, such

as X-rays, to image parts of the body.

(See also imaging techniques; radiology.)

radioimmunoassayA sensitive labo-

ratory technique that uses radioactive

isotopes to measure the concentration

of proteins such as hormones or anti-

bodies in blood. (See also immunoassay.)

radioisotope scanningSee radionu-

clide scanning.

radiologyThe medical speciality that

makes use of X-rays, ultrasound, MRI,

and radionuclide scanningfor investiga-

tion, diagnosis, and treatment.

Radiological methods provide images

of the body in anoninvasiveway so that

exploratory surgery is not needed. The

techniques also enable instruments

(such as needles and catheters) to be

accurately guided into different parts of

the body for diagnosis and treatment.

This is called interventional radiology.

radiolucentA term for anything that is

almost transparent to radiation, espe-

cially to X-raysand gamma radiation.

radionuclide scanningA diagnostic

technique based on detection of radia-

tionemitted by radioactive substances

introduced into the body. Substances

are taken up to different degrees by dif-

ferent tissues, allowing specific organs

to be studied. For example, iodine is

taken up mainly by the thyroid gland, so

by “tagging” a sample of iodine with a

radioactive marker (radionuclide), the

uptake of iodine can be monitored to

investigate the functioning of the gland.

A radionuclide is swallowed or injec-

ted into the blood and accumulates

in the target organ. It emits radiation in

the form of gamma radiation, which is

detected by a gamma camera to pro-

duce an image. Cross-sectional images

(“slices”) can be obtained using a com-

puter-controlled gamma camera that

rotates around the patient. This special-

ized form of radionuclide scanning is

known as SPECT (single photon emis-

sion computed tomography). Moving

RADICULOPATHY RADIONUCLIDE SCANNING

R

RADIONUCLIDE SCANNING

Gamma camera counterbalance

Adjustable

bed

Radiographer

Monitor

displays

image

Control

panel

Gamma

camera