calcification
The process by which noncellular material in the body becomes hardened due to deposits of calcium and other materials.

calcium score
A number reflecting the degree and extent of calcium deposits in the walls of the coronary arteries, as demonstrated by cardiac computed tomography.

cancer
(kan-ser)
General term frequently used to indicate any of various types of malignant neoplasms, most of which invade surrounding tissues, may metastasize to several sites, and are likely to recur after attempted removal and to cause death of the patient unless adequately treated.

cardiac catheterization
A diagnostic procedure in which a catheter is placed in a large vein in the leg or arm and advanced to the heart to check for blood pressure within the heart, oxygen in the blood, and/or pumping ability of the heart muscle. (Also see angiography and angioplasty.)

cardiac pacemaker
An electrical device, often implanted, that maintains a normal heart rhythm by stimulating the heart muscle.

cardiologist
A physician specializing in the diagnosis and treatment of heart disease.

carotid artery
(ka-rot-id ar-ter-E)
Major vessel(s) running through either side of the neck, which supply blood to the brain.

CAT scan
See computed tomography (CT).

cathartic
A substance that causes evacuation of the bowel.

catheter
(kath-i-ter)
    1.A tubular instrument to allow passage of fluid from or into a body cavity.
    2.Especially a catheter designed to be passed through the urethra into the bladder to drain it of retained urine.
    3.A flexible, hollow plastic or rubber tube that may be passed into a blood vessel to withdraw fluids or inject medicine or contrast materials.

catheter angiography
An examination of blood vessels by injecting contrast material directly into an artery through a small plastic tube.

catheter-directed thrombolysis
A procedure in which a catheter is inserted through the skin into a vessel and directed to a blood clot in a fistula or graft of a hemodialysis patient. A medication or mechanical device delivered via the catheter is used to break up the clot and restore blood flow.

cauterize
To use heat, usually from radiofrequency energy or a laser, to destroy tissue or seal blood vessels.

centigray (cGy)
Abbreviated form of centigray, a unit of radiation dose equal to 0.01 gray. Equivalent to rad, the older term for radiation dose.

cerebral
Relating to the brain.

cerebrospinal fluid
Fluid that surrounds the brain and spinal cord and helps to cushion and protect them.

cervical
Refers to the neck region of the spinal column which includes seven bones, or vertebrae, labeled C-1 through C-7.

cervix
The lower part of the uterus, connecting the uterus with the vagina.

chemotherapy
(kEm-O-ther-a-pE)
Treatment of disease by means of chemical substances or drugs; usually used in reference to neoplastic (cancer) disease.

claustrophobic
(klaw-strO-fO-bik)
A morbid fear of being in a confined place.

clinical trials
Studies that test new treatments.

clot
To coagulate or turn from a free-flowing liquid to a thickened or semi-solid state.

coagulate
To change from a liquid to a thickened or solid state. Blood that does not flow smoothly through a vessel can coagulate or clot by turning from a free-flowing liquid to a semi-solid gel.

cobalt (Co)
(kO-bawlt)
A steel-gray metallic element, atomic no. 27, atomic wt. 58.93320; a bioelement and a constituent of vitamin B12; certain of its compounds are pigments, e.g., cobalt blue.

cobalt-60 radiation therapy
Cobalt-60-based or photon radiation therapy machines are used exclusively to treat brain tumors and abnormalities. See also Gamma Knife.

collodion
A liquid that, on evaporation, leaves a protective film over cuts.

colonoscopy
(kO-lon-os-ko-pE)
Visual examination of the inner surface of the colon by means of a lighted, flexible tubular instrument inserted into the colon through the rectum.

color Doppler
Color Doppler uses a computer to convert the Doppler measurements into an array of colors. This color visualization is combined with a standard ultrasound picture of a blood vessel to show the speed and direction of blood flow through the vessel.

colorectal cancer
Malignant disease affecting the colon and rectum. See the Colorectal Cancer page for more information.

colostomy
Establishment of an artificial opening into the colon.

computed tomography (CT)
(tO-mog-ru-fE)
Sometimes referred to as CAT scan (computerized axial tomography). Imaging anatomical information from a cross-sectional plane of the body, each image generated by a computer synthesis of x-ray transmission data obtained in many different directions in a given plane.
 
computed tomography (CT) angiography
( tO-mog-ru-fE an-jE-O-gra-fE)
A method of examining blood vessels utilizing x-rays and injection of iodine-containing contrast medium.

Cone
A linear accelerator attachment for electron beam treatment.

conformal radiation therapy
Use of a CT image to tailor the radiotherapy beam to the exact size and shape of a tumor.

congenital
Existing at birth.

congenital heart disease
A heart problem that has existed since birth.

congestive heart failure
A condition in which the heart cannot adequately pump blood forward, leading to a back-up of blood in vessels and an accumulation of fluid in body tissues including the lungs.

constipation
(kon-sti-pA-shun)
A condition in which bowel movements are infrequent or incomplete.

contrast agent
See contrast material.

contrast material
Also referred to as contrast agent or contrast medium. Any internally administered substance that has a different opacity from soft tissue on radiography or computed tomography. Includes:
    • Barium or water, used to make parts of the gastrointestinal tract opaque.
    • Iodine in water, used for arthrography.
    • Water soluble iodine, used to make blood vessels opaque; to demonstrate the inner structures of the urinary tract (kidneys, ureters and bladder); and to outline joints (the spaces between two bones).
    • Iodine mixed with water or oil may be used to evaluate the fallopian tubes and lining of the uterus.
    • Sterile saline (salt water) is used during hysterosonography.
    • May refer to air occurring naturally or introduced into the body.
    • Paramagnetic substances used in magnetic resonance imaging.

core needle biopsy
A type of biopsy in which a large hollow needle is inserted through the skin to the site of an abnormal growth to collect and remove a sample of cells for analysis. This procedure uses an automated needle, which obtains one sample of tissue at a time and is re-inserted several times.

coronary arteries
(kOr-o-nAr-E ar-ter-Es)
The arteries that supply freshly oxygenated blood to the heart muscle.

coronary artery disease
A condition involving the narrowing of the coronary arteries that carry blood and oxygen to the heart muscle.

coronary bypass surgery
A surgical means of rerouting blood in the coronary artery system around diseased vessels.

cranial
Related to the bony skull known as the cranium that holds the brain.

Crohn's disease (also known as regional enteritis)
A moderately severe chronic inflammation of the intestine, especially of the small intestine, of unknown cause, involving the obstruction of the lower part of the small bowel and less frequently other parts of the gastrointestinal tract. It is characterized by patchy deep ulcers that may cause abnormal passages within the bowel, and narrowing and thickening of the bowel. Symptoms include fever, diarrhea, cramping abdominal pain, and weight loss.
cryoablation
See cryosurgery.

cryoprobe
An instrument used to apply extreme cold to a selected anatomic area.

cryosurgery
Also known as cryotherapy, cryoablation or targeted cryoablation therapy.
A minimally invasive treatment that uses extreme cold in the form of liquid nitrogen or argon gas to freeze and destroy diseased tissue, including cancer cells.

cryotherapy
See cryosurgery.

CT or CAT Scan
An imaging study using X-rays and a computer to create cross-sectional pictures of the body.

curettage
See dilation and curettage (D&C).
curie (C, c, Ci)
(kyu-rE)
A unit of measurement of radioactivity, 3.70 ×1010 disintegrations per second; formerly defined as the radioactivity of the amount of radon in equilibrium with 1 gm. of radium; superseded by the S.I. unit, the becquerel (1 disintegration per second). Origin [Marie (1867-1934) and Pierre (1859-1906) Curie, French chemists and physicists and Nobel laureates]

cyclotron
A type of particle accelerator in which charged particles are propelled by an alternating electric field between two large electrodes in a constant magnetic field created by two large magnets. The particles are injected at the center of the magnet and spiral outward as their energy increases. Protons produced in a cyclotron can be used to treat cancer, and cyclotron-produced protons can create radioisotopes for nuclear medical procedures.

cystic fibrosis
An inherited disease in which the lungs, intestines and pancreas become clogged with thick mucus, interfering with normal digestion and breathing.

cystography
(sis-tog-ru-fE)
Radiography of the bladder, following injection of a radiopaque substance.

cysts
(sists)
Abnormal sacs containing gas, fluid, or a semisolid material, with a membranous lining.