D's Flashcards
dacryocystorhinography
A radiographic contrast study of the nasolacrimal duct.
decubitus
Position assumed when lying down. Opposed to erect or standing.
degenerative joint disease (DJD)
The most common joint disorder in dogs and cats, characterized by degradation of articular cartilage and subchondral bone (also called osteoarthritis and osteoarthrosis). May result from trauma,
infection, age-related wear, overuse, developmental anomalies,
immune-mediated disease, and other causes. The most
common radiographic sign is osteophyte formation.
definition
Refers to the margination of a lesion and is affected by the degree of activity and aggressiveness of a disease process. Definition should not be confused with (1) detail, which is affected by technical factors, (2) shape, which may be smooth or irregular, or (3) opacity interfaces, which are affected by patient’s body condition, presence of effusion, etc.
Examples:
• A well-defined periosteal response is inactive; an illdefined
periosteal response is active.
• Well-defined osteolysis is less aggressive; ill-defined osteolysis
is more aggressive.
• A well-defined pulmonary nodule is more likely to be a
tumor; an ill-defined lung nodule is more typical of an
abscess or mycotic granuloma.
discography
A radiographic contrast study of the central portion of an intervertebral disc.
discospondylitis
Inflammation or infection of an intervertebral disc (other names: intradiscal osteomyelitis, diskitis).
disseminated idiopathic skeletal hyperostosis (DISH)
Flowing mineralization along contiguous vertebral
bodies. DISH resembles severe spondylosis deformans.
Other names: Forestier’s disease (human medical term).
distal: Away from the center of the body. Opposed to proximal (Figure 2.22).
distortion
(1) Geometric distortion occurs when one part of the patient (subject or object) is positioned further from the detector than other parts, creating uneven magnification.
(2) Positional distortion refers to errors in positioning, such as rotation of the sternum on a ventrodorsal radiograph or placing a structure of interest at the periphery of the field of view, which can falsely alter the normal appearance.
diverticulum
A pouch or sac extending outward from a hollow organ or structure (e.g. stomach, intestine, esophagus, urinary bladder).
donut sign
Refers to the end-on visualization of a bronchus with a thickened wall, increased endobronchial secretions,
or peribronchial infiltrate. Characteristic of a bronchial
pulmonary pattern.
dolichocephalic
Refers to the shape of a skull in which the nasal cavity is longer than the cranium. The occipital crest tends to be prominent in animals with this type of skull. Examples: Collie, Greyhound.
dorsal
Toward the back or spine. Opposed to ventral. Also
refers to the top, front, or extensor surface of limbs (at or
below the carpus and tarsus) and the top of the head (Figure
2.22).
dorsal recumbency
Animal is positioned lying on its back
dorsopalmar/plantar
Describes the path of the x-ray beam (x-rays enter the dorsum of the limb and exit the palmar/plantar surface).
dorsoventral (DV) radiograph
The x-ray beam enters the dorsal surface of a body part and exits the ventral surface
Dose
The recommended quantity of an agent required for therapy or a specific procedure
double contrast
A radiographic contrast study using negative (e.g., gas) and positive contrast media (e.g., barium, iodinated agents).
double physis sign
Refers to the line of decreased opacity within the metaphysis parallel to the physis in animals suffering from hypertrophic osteodystrophy.
delayed union fracture
The bone fragments do not unite within the expected period of time, but healing is believed to eventually occur.
density
Radiographic density refers to the degree of blackening of a radiograph. Physical density refers to the characteristic of a material to block x-rays. Previously, the term density was used synonymously with opacity. Density is stillused to describe opacity on CT images
detail
Refers to the edge sharpness of structures as seen on a radiograph. Detail is affected by technical factors such
as exposure settings, motion artifact, type of film:screen
system, focal spot size, etc. It is one of the four quality characteristics of a radiograph (density, detail, distortion, contrast). Detail has nothing to do with the patient and everything to do with how the radiograph was created.
Detail should not be confused with (1) definition, which is
affected by activity and aggressiveness of a disease process
or (2) opacity interfaces, which are affected by patient’s body
condition, presence of effusion, etc. Detail is enhanced by
using a small focal spot, tight collimation, larger distance
between focal spot and detector, and a shorter distance
between subject and detector. A slow-speed film:screen
system or a digital system with high spatial resolution will
provide better detail. Other factors that increase detail
include using a grid to reduce scatter radiation and avoiding
patient motion.
detector
The part of an imaging system that captures the image. A detector may be film (conventional radiography) or a phosphor plate (digital radiography). X-rays that pass through the patient to the detector form the latent image.Other names: image detector, image receptor.
development of x-ray film
Refers to the chemical process that converts activated silver halide crystals to metallic silver particles. Silver particles blacken the film to createthe final image. Development may be accomplished manually or using an automatic film processor.
diaphysis
Between physes”; the middle portion or shaft of a long bone; the area between the metaphyses; a primary center of ossification of a long bone.
