Computed and Digital Radiography Finals Review

Vocabulary terms and definitions covering image evaluation, noise components, contrast, artifacts, and radiology data management systems.

Exposure Indicator

A numeric value indicating the level of radiation exposure to the image receptor.

Image Noise

Background information received by the IR that contributes no useful diagnostic information and reduces image quality; often appearing as a mottled, salt-and-pepper look.

Film Graininess

A component of noise inherent in the IR that refers to the distribution in size and space of silver halide grains in the emulsion; not under the control of the RT.

Structure Mottle

A component of noise inherent in the IR caused by phosphor crystals in the radiographic intensifying screen; not under the control of the RT.

Quantum Mottle

The principal contributor to radiographic noise caused by the random nature by which X-rays interact with the IR; it is under the control of the RT.

Scatter Radiation

A type of secondary radiation resulting from Compton interaction that occurs when the beam intercepts an object.

Contrast

The variation in brightness and density levels on a radiograph required to differentiate anatomic tissues.

Long Scale Contrast

Demonstrates light difference between structures and has a maximum total number of densities.

Short Scale Contrast

Demonstrates considerable differences between structures and has a minimum total number of densities.

Physical Contrast

The total range of density/exposure values recorded by the image receptor.

Visible Contrast

The total range of density/exposure values that can be perceived by the human eye when looking at an image.

Recorded Detail

The degree of geometric sharpness or accuracy of the structural lines actually recorded in the image.

Image Distortion

Any misrepresentation or inaccurate impression of the target structure, categorized as size or shape distortion.

Size Distortion

Refers to magnification of the target structure.

Shape Distortion

Refers to elongation or foreshortening of the target structure.

Artifact

An unwanted image on a radiograph that decreases the overall image quality.

Detector Drop Artifacts

A white smoothly edged defect or straight lines caused by dropping wireless flat panel detectors, leading to cracked readout circuitry or loss of adhesion.

Disparity Artifacts

Alteration in image contrast caused by a malfunctioning CR reader or defective scanning.

Light Bulb Effect

A darkening of the lower and outer portions of an image caused by high kV, scatter radiation, or improper collimation.

Delayed Scanning

An artifact appearing as fading of the image because of a delay of 12 hours or more between acquisition and processing.

Midgray Clipping Artifact

Loss of contrast in certain areas caused by poor contrast enhancement.

Hyporetention Artifact

A yellowish stain on a finished radiograph caused by inadequate washing of the film.

Moiré Effect

A wavelike, cloudy, or frosted appearance caused by incorrectly oriented grid lines running parallel to the plate reader's scan lines.

Quality Assurance

A program used by management to maintain optimal diagnostic image quality with minimum hazard and distress to patients.

Reject Analysis

A quality indicator and critical tool for dose and image quality optimization in radiology departments.

Primary Monitors

High-quality display monitors used specifically by radiologists for diagnostic interpretation.

Cathode Ray Tube (CRT)

A type of display monitor with an electron gun, cathode, focusing/deflecting coils, and anode, typically featuring a curved face plate.

Liquid Crystal Display (LCD)

A monitor technology that passes light through liquid crystals to display images on a glass faceplate.

Hospital Information System (HIS)

A database application primarily storing patient demographic details and contact info; also known as the Master Patient Index or Patient Administration System.

Radiology Information System (RIS)

A group of applications used to handle textual data related to imaging procedures, such as scheduling, tracking, and report generation.

Picture Archiving and Communication System (PACS)

A centralized computer-based system designed to acquire, store, and view healthcare images over a network.

Digital Imaging and Communications in Medicine (DICOM)

A standard protocol for the management and transmission of medical images and related data, unique to radiographs.

Teleradiology

The reading of images from outside of the hospital's walls, where images are acquired in one location but reported from another.

Annotation

The manual text input or selection of preset terms on a digital image, such as side identification, which should not substitute anatomical markers.

Workflow

The step-by-step description of how an examination is completed, from order entry to transcribed report.