A's Flashcards
abscess:
An accumulation of purulent material in an abnormal cavity surrounded by a wall and typically associated with inflammation. May be caused by infection or presence of foreign material.
air bronchogram sign:
Associated with an alveolar lung pattern, this sign refers to air retained in a bronchus that appears as a tubular, branching, less opaque structure surrounded by soft tissue opacity lung parenchyma. The degree of contrast between the air-filled bronchus and soft tissue–filled alveoli depends on the degree of alveolar filling (i.e.,more complete filling = more contrast). Air bronchogramsare the classic sign of an alveolar pattern but do not occurwith all alveolar patterns (in addition to the alveoli, the bronchi may become filled or collapsed).
achondroplasia:
“Without cartilage formation”; a genetic disorder of bone growth that results in disproportionate dwarfism. Appendicular bones are short and thick, metaphyses are cupped and flared, and physes are irregular. Some dog breeds normally are classified as achondrodysplastic (e.g.,Bulldog) (a term that often is used interchangeably with chondrodystrophic).
air gap
Distance between patient (subject or object) and image detector; increasing the air gap allows scattered x-rays to dissipate but results in magnification of the image.
ALARA (as low as reasonably achievable):
The overriding principle of radiation safety. Understanding that some radiation exposure is necessary, it must be demonstrated that further reducing the exposure would be grossly disproportionate to the benefit gained; that is, the medical benefit must be worth the exposure risk when using radiation. Factors influencing the degree of exposure to radiation include amount of shielding, distance from source of x-rays, time spent in presence of x-rays, and quality/quantity of x-rays
aliasing
On digital radiographs, an artifact that appears as a series of repeating lines superimposed on the image.
alveolar filling
Refers to replacement of air in normally air-filled spaces in lung by fluid (e.g., blood, edema) or cells(e.g., neoplasia, purulent material). Any solid area of soft tissue opacity in the lung that is not vessel, nodule, or mass is alveolar filling.
alveolar pulmonary pattern
A radiographic appearance that occurs when air normally present in alveoli is displaced by fluid, cells, or collapse of the alveoli. Appears as soft tissue opacity in the lung that obscures the margins of adjacent soft tissue structures (e.g., blood vessels, pulmonary nodules, diaphragm, cardiac silhouette). The air bronchogram sign is characteristic of an alveolar pattern but is not necessary for diagnosis of an alveolar pattern. Common causes include pneumonia, hemorrhage, neoplasia, edema, and atelectasis. Lung collapse (atelectasis) may appear as alveolar filling and can only be estimated due to decreasedlung size causing a mediastinal shift.
angiocardiography
A radiographic contrast study of the heart and great vessels.
angiography
A radiographic contrast study of blood vessels.
Anode
Positive terminal in x-ray tube. Anode attracts electrons from cathode (negative terminal). Anode contains a tungsten target made of metal with a high melting point to withstand the intense heat generated by the electron beam.
apophysis
Essentially, a non-weight-bearing epiphysis; a normal bony projection that serves for the attachment of tendons or ligaments (e.g., greater trochanter, tibial tuberosity)
appendicular
Pertaining to the limbs.
arteriovenous fistula
An abnormal communication between an artery and a vein.
arthritis
Inflammation of a joint; may be caused by trauma, infection, or immune-mediated disease. Term often is erroneously used for degenerative joint disease.
atelectasis
Incomplete expansion of part or all of a lung (i.e., partial or complete lung collapse). May result from disease of lung or pleural space. Common with animals positioned in lateral recumbency.
