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205 Cards in this Set

  • Front
  • Back

Chemical, usually acetic acid in the fixer and sodium carbonate in the developer, used to neutralize the developer and swell the gelatin.
Activator
Phosphorescence in an intensifying screen.

Afterglow
Practice of moving the image receptor 10 to 15 cm from the patient so that fewer scattered x-rays interact with the image receptor, thereby enhancing contrast.
Air-gap technique
Computer-adapted mathematical calculation applied to raw data during image reconstruction.

Algorithm
Technique by which graphics on the console guide the technologist in selection of a desired kVp and mAs
Anatomically programmed radiography (APR)
Circular opening for the patient in the gantry of a computed tomographic or magnetic resonance imaging system. b. Fixed collimation of a diagnostic x-ray tube, as in an aperture diaphragm. c. Variable opening before the lens of a cine or photospot camera.

Aperture
Simple beam-restricting device that attaches a lead-lined metal diaphragm to the head of the x-ray tube.
Aperture diaphragm
X-ray beam pattern that usually is shaped like a square or a rectangle, and that is used in conventional radiography and fluoroscopy
Area beam
Part of a computer that handles raw data and performs the mathematical calculations necessary to reconstruct a digital image.
Array processor
Reduction in radiation intensity that results from absorption and scattering.
Attenuation
Feature that determines radiation exposure during radiography in most x-ray imaging systems.
Automatic exposure control (AEC)
Measure of radiographic contrast.
Average gradient
X-rays that have interacted with an object and are deflected backward.

Backscatter radiation
Area that serves as a mechanical support for the active phosphor layer in a radiographic intensifying screen.
Base
Optical density inherent in the base of the film.
Base density
Average density from an unexposed area of the strips.
Base plus fog (B+F)
Device that provides a means of restricting the size of an x-ray field.
Beam-limiting device
Ability of an x-ray beam to penetrate tissue
Beam penetrability
Device that restricts the size of the x-ray field to only the anatomic structure of interest.
Beam restrictor
Number of bits used to reproduce image gray levels (e.g., 8 bits=28 =256 gray levels).
Bit depth
Ability of the image intensifier to increase the illumination level of the image.
Brightness gain
Alkali compound in the developer that enhances the action of the developing agent by controlling the concentration of hydrogen ions.
Buffering agent
Instrument with two bent or curved legs used for measuring the thickness of a solid.
Calipers
Rigid holder that contains the film and screens.
Cassette
X-ray beam composed of x-rays that travel along the center of the useful x-ray beam.
Central axis x-ray beam
Processing hardware in large computers.
Central processing unit (CPU)
Center of the x-ray beam that interacts with the image receptor.
Central ray
Graph of optical density versus log relative response; H & D curve
Characteristic curve
Solid-state device that converts visible light photons to electrons.
Charge-coupled device (CCD)
Artifact produced by chemical contamination of the developer.
Chemical fog
A chemical, usually ammonium thiosulfate, that is added to the fixer to remove undeveloped silver bromine from the emulsion.
Clearing agent
Restriction of the useful x-ray beam to reduce patient dose and improve image contrast.
Collimation
Material inserted between an x-ray source and a patient to shape the intensity of the x-ray beam. An x-ray beam filter is designed to make the remnant beam more uniform in intensity.
Compensating filter
The act of flattening soft tissue to improve optical density
Compression
Radiographic technique that uses a photostimulable phosphor as the image receptor and an area beam.
Computed radiography (CR)
Circular metal tube that attaches to x-ray tube housing to limit the beam size and shape.
Cone
Misalignment of cones that causes one side of the radiograph to not be exposed because the edge of the cone may interfere with the x-ray beam.
Cone cutting
Degree of difference between the light and dark areas of a radiograph
Contrast
Ratio of radiographic contrast with a grid to that without a grid.
Contrast improvement factor
Difference between the step with an average optical density closest to 2.2 and the step with an average optical density closest to, but not less than, 0.5.
Contrast index
Agent that enhances differences between anatomic structures.
Contrast medium
Ability to distinguish between and to image similar tissues.
Contrast resolution
Rate at which x-ray energy is transformed into light in an intensifying screen.
Conversion efficiency (CE)
Grid on which lead strips run parallel to the long and short axes.
Crossed grid
Instrument that measures the optical density of exposed film.
Densitometer
The difference between the step with an average optical density closest to 2.2 and the step with an average optical density closest to, but not less than, 0.5.
Density difference (DD)
Degree of sharpness of structural lines on a radiograph.
Detail
Percentage of x-rays absorbed by the screen by the image receptor.
Detective quantum efficiency (DQE)
Stage of processing during which the latent image is converted to a manifest image.
Developing
A chemical, usually phenidone, hydroquinone, or Metol, that reduces exposed silver ions to atomic silver.
Developing agent
Artifact that results from reduction of crystals that had not been exposed to metallic silver caused by the lack of a restrainer.
Development fog
Different degrees of absorption in different tissues that result in image contrast and formation of the x-ray image.
Differential absorption
Static images produced with a fan x-ray beam intercepted by a linear array of radiation detectors or an area x-ray beam intercepted by a photostimulable phosphor plate or a direct-capture solid-state device.
Digital radiography (DR)
Film used without intensifying screens
Direct-exposure film
Unequal magnification of different portions of the same object.
Distortion
Radiographic film that has an emulsion coating on both sides of the base and a layer of supercoat over each emulsion.
Double-emulsion film
Single-emulsion film that is exposed to ultraviolet light or blue light through the existing radiograph to produce a copy
Duplicating film
Range of values that can be displayed by an imaging system; shades of gray.
Dynamic range
Accentuation of the interface between different tissues.
Edge enhancement
Area projected onto the patient and the image receptor.
Effective focal-spot size
Image that is made to appear longer than it really is because the inclined object is not located on the central x-ray beam.
Elongation
Material with which x-rays or light photons from screens interact and transfer information.
Emulsion
X-rays that remain after the beam exits through the patient.
Exit radiation
Factors that influence and determine the quantity and quality of x-radiation to which the patient is exposed.
Exposure factors
Electrons that bounce off the focal spot and land on other areas of the target.
Extrafocal radiation, off-focus radiation
Image matrix size provided by digital x-ray imaging systems.
Field of view (FOV)
Principle that states that if the optical density on a radiograph is to be increased with the use of kVp, an increase in kVp by 15% is equivalent to doubling of the mAs.
Fifteen percent rule
Distribution of silver halide grains in an emulsion.
Film graininess
Removal of low-energy x-rays from the useful beam with aluminum or another metal. It results in increased beam quality and reduced patient dose.
Filtration
Principle that states that an increase of 5% in the kVp may be accompanied by a 30% reduction in the mAs to produce the same optical density at a slightly reduced contrast scale.
Five-percent rule
Stage of processing during which the silver halide not exposed to radiation is dissolved and removed from the emulsion.
Fixing
Emission of visible light only during stimulation.
Fluorescence
Imaging modality that provides a continuous image of the motion of internal structures while the x-ray tube is energized. Real-time imaging.
Fluoroscopy
Region of the anode target in which electrons interact to produce x-rays.
Focal spot
Blurred region on the radiograph over which the technologist has little control.
Focal-spot blur
Radiographic grid constructed so that the grid strips converge on an imaginary line.
Focused grid
Unintended optical density on a radiograph that reduces contrast through light or chemical contamination.
Fog
Development of silver grain that contains no useful information.
Fog density
Reduction in image size; related to the angle of inclination of the object.
Foreshortening
Part of the emulsion that provides mechanical support for the silver halide crystals by holding them uniformly dispersed in place.
Gelatin
Slope of the tangent at any point on the characteristic curve.
Gradient
Image display in which intensity is recorded as variations in brightness.
Gray scale
Device used to reduce the intensity of scatter radiation in the remnant x-ray beam.
Grid
Ability of a grid to absorb scatter radiation
Grid cleanup
Absence of optical density on a radiograph caused by unintended x-ray absorption in a grid.
Grid cutoff
Number of grid lines per inch or centimeter
Grid frequency
Series of sections of radiopaque material.
Grid lines
Ratio of grid height to grid strip separation
Grid ratio
Reflection of screen light transmitted through the emulsion and base.
Halation
Permanent image on film or paper, as opposed to an image on a cathode ray tube, a disc, or magnetic tape.
Hard copy
A chemical, usually potassium glutaraldehyde alum in the fixer, that is used to stiffen and shrink the emulsion.
Hardener
X-ray that has high penetrability and therefore is of high quality
Hard x-ray
Absorption of x-rays in the heel of the target, resulting in reduced x-ray intensity to the anode side of the central axis.
Heel effect
Ability to image small objects with high subject contrast; spatial resolution.
High-contrast resolution
Sharpness of small structures on the radiograph.
Image Detail
Layout of cells in rows and columns
Image matrix
Deterioration of the radiographic image.
Image noise
Medium that transforms the x-ray beam into a visible image; radiographic film or a phosphorescent screen.
Image receptor (IR)
Ratio of exposure without screens to that with screens to produce the same optical density.
Intensification factor (IF)
Hardware and software that enable imaging systems to interconnect and to connect with printers.
Interface
Time during which the signal from an image detector is sampled
Interrogation time
Sections of radiolucent material in a grid.
Interspace material
Law that states that the intensity of radiation at a location is inversely proportional to the square of its distance from the source of radiation.
Inverse square law
Equal intensity in all directions; having the same properties in all directions.
Isotropic
Unobservable image stored in the silver halide emulsion; it is made manifest by processing.
Latent image
Sensitivity center that has many silver ions attracted to it.
Latent image center
(sensitivity speck)
Improper positioning of the grid that results in cutoff.
Lateral decentering
Range of x-ray exposure over which a radiograph is acceptable.
Latitude
Design incorporated into x-ray tube targets to allow a large area for heating while a small focal spot is maintained.
Line focus
principle
Change in optical density over each exposure interval.
Log relative exposure (LRE)
Low-contrast radiograph that has many shades of gray.
Long gray scale
Matrix of data that manipulates the values of gray levels, converting an image input value to a different output value.
Look-up table (LUT)
Ability to image objects with similar subject contrast.
Low-contrast resolution
Emission of visible light
Luminescence
The observable image that is formed when the latent image undergoes proper chemical processing.
Manifest image
Rows and columns of pixels displayed on a digital image.
Matrix
Reconstruction of an image through selection of the highest-value pixels along any arbitrary line in the data set; only those pixels are exhibited.
Maximum-intensity projection (MIP)
Product of exposure time and x-ray tube current; measure of the total number of electrons
Milliampere-second (mAs)
Blurring of the image that results from movement of the patient or the x-ray tube during exposure
Motion blur
a. Grainy or uneven appearance of an image caused by an insufficient number of primary x-rays. b. Uniform signal produced by scattered x-rays.
Noise
Distance from the image receptor to the object that is to be imaged.
Object-to-image receptor distance (OID)
Artifact produced by an improperly positioned radiographic tube—not by an improperly positioned grid.
Off-level grid
Surface that does not allow the passage of light.
Opaque
Degree of blackening of a radiograph
Optical density
Referring to blue- or green-sensitive film; usually exposed with rare Earth screen.
Orthochromatic
Referring to a radiograph that is too dark because too much x-radiation reached the image receptor.
Overexposed
Referring to film that is sensitive to the entire visible light spectrum.
Panchromatic
Ability of an x-ray to penetrate tissue; range in tissue; x-ray quality.
Penetrability
Image blur that results from the size of the focal spot; geometric unsharpness
Penumbra
Active layer of the radiographic intensifying screen closest to the radiographic film.
Phosphor
Emission of visible light during and after stimulation.
Phosphorescence
Device that allows automatic exposure control.
Phototimer
Picture element; the cell of a digital image matrix.
Pixel
Chemical treatment of the emulsion of a radiographic film to change a latent image to a manifest image.
Processing
Layer of the radiographic intensifying screen closest to the radiographic film
Protective coating
Radiographic noise produced by the random interaction of x-rays with an intensifying screen. This effect is more noticeable when very high rare Earth systems are used at a high kVp.
Quantum mottle
Artifact caused by unintentional exposure to radiation.
Radiation fog
Relative penetrability of an x-ray beam determined by its average energy; usually measured by half-value layer or kilovolt peak.
Radiation quality
Intensity of radiation; usually measured in milliroentgen (mR).
Radiation quantity
Combined result of image receptor contrast and subject contrast.
Radiographic contrast
Device that converts the energy of the x-ray beam into visible light to increase the brightness of an x-ray image.
Radiographic intensifying screen
Undesirable fluctuation in the optical density of the image.
Radiographic noise
Combination of settings selected on the control panel of the x-ray imaging system to produce a quality image on the radiograph.
Radiographic technique
Guide that describes standard methods for consistently producing high-quality images.
Radiographic Technique Chart
Radiographic noise produced by the random interaction of x-rays with an intensifying screen. This effect is more noticeable when very high rare Earth systems are used at a high kVp.
Quantum mottle
Artifact caused by unintentional exposure to radiation.
Radiation fog
Relative penetrability of an x-ray beam determined by its average energy; usually measured by half-value layer or kilovolt peak.
Radiation quality
Intensity of radiation; usually measured in milliroentgen (mR).
Radiation quantity
Combined result of image receptor contrast and subject contrast.
Radiographic contrast
Device that converts the energy of the x-ray beam into visible light to increase the brightness of an x-ray image.
Radiographic intensifying screen
Undesirable fluctuation in the optical density of the image.
Radiographic noise
Combination of settings selected on the control panel of the x-ray imaging system to produce a quality image on the radiograph.
Radiographic technique
Guide that describes standard methods for consistently producing high-quality images.
Radiographic Technique Chart
Referring to a tissue or material that transmits x-rays and appears dark on a radiograph.
Radiolucent
Referring to a tissue or material that absorbs x-rays and appears bright on a radiograph.
Radiopaque
Radiographic intensifying screen made from rare Earth elements, which make it more useful for radiographic imaging.
Rare Earth screen
Principle that states that optical density on a radiograph is proportional only to the total energy imparted to the radiographic film.
Reciprocity law
Creation of an image from data
Reconstruction
Time needed for the computer to present a digital image after an examination has been completed.
Reconstruction time
Degree of sharpness of structural lines on a radiograph.
Recorded detail
Filter that transmits light only above 600 nm; it is used with both green- and blue-sensitive film.
Red filter
Chemical responsible for reduction.
Reducing agent
Layer of the intensifying screen that intercepts light headed in other directions and redirects it to the film.
Reflective layer
Area of an anatomic structure on a reconstructed digital image as defined by the operator using a cursor.
Region of interest (ROI)
X-rays that pass through the patient and interact with the image receptor.
Remnant radiation
Replacement of developer and of fixer in the automatic processing of film.
Replenishment
Measure of the ability of a system to image two separate objects and visually distinguish one from the other.
Resolution
Compound that restricts the action of the developing agent to only irradiated silver halide crystals.
Restrainer
Incandescent lamp with a color filter that provides sufficient illumination in the darkroom while ensuring that the film remains unexposed.
Safelight
X-rays scattered back in the direction of the incident x-ray beam.
Scatter radiation
The phosphorescence in an intensifying screen.
Screen lag
Relative number used to identify the efficiency of conversion of x-rays into usable light.
Screen speed
The most commonly used film; used with intensifying screens
Screen-film
Ratio of primary radiation to scattered radiation transmitted through the grid.
Selectivity
Ability of an image receptor to respond to x-rays.
Sensitivity
Physical imperfections in the lattice of the emulsion layer that occur during the film manufacturing process.
Sensitivity center (speck)
Optical step wedge that is used to construct a characteristic curve.
Sensitometer
Study of the response of an image receptor to x-rays
Sensitometry
Type of distortion caused by elongation or foreshortening.
Shape distortion
High-contrast radiograph that exhibits black to white in just a few apparent steps.
Short gray scale
Material that makes up 98% of the silver halide crystals in a typical emulsion
Silver bromide
Active ingredient of the radiographic emulsion. It is instrumental in creating a latent image on the radiograph
Silver halide crystals
Material that makes up 2% of the silver halide crystals in a typical emulsion.
Silver iodide
Output on a display screen.
Soft copy
X-ray that has low penetrability and therefore is of low quality.
Soft x-ray
Distance from the x-ray tube to the image receptor.
Source-to-image receptor distance (SID)
Misrepresentation in the image of the actual spatial relationships among objects.
Spatial distortion
Measure of resolution; usually expressed in line pairs per millimeter (lp/mm).
Spatial frequency
Constancy of pixel values in all regions of the reconstructed image
Spatial uniformity
Use of rare Earth screens only in conjunction with film emulsions that have light absorption characteristics matched to the light emission of the screen.
Spectrum matching
Term used to loosely describe the sensitivity of film to x-rays.
Speed
Principle that states that one can compensate for a change in the source-to-object distance by changing the mAs by the factor SID squared.
Square law
Portion of a sensitometric curve in which the diagnostic or most useful range of density is produced.
Straight-line portion
Distribution of phosphor crystals in an intensifying screen.
Structure mottle
Component of radiographic contrast determined by the size, shape, and x-ray attenuating characteristics of the subject who is being examined and the energy of the x-ray beam. See also Image receptor contrast.
Subject contrast
The kVp and mA as selected for a given radiographic examination.
Technique factors
Referring to a radiograph that is too light because too little x-radiation reaches the image receptor.
Underexposed
Primary radiation used to form an image.
Useful beam
Box-shaped device that contains a radiographic beam–defining system. It is the device that is most often used to reduce the size and shape of a radiographic beam.
Variable aperture collimator
Stage of processing during which any remaining chemicals are removed from the film.
Washing
Agent, usually water, that treats the radiograph so that chemicals can penetrate the emulsion.
Wetting agent
Location on a digital image number scale at which the levels of grays are assigned. It regulates the optical density of the displayed image and identifies the type of tissue to be imaged.
Window level
Specific number of gray levels or digital image numbers assigned to an image. It determines the grayscale rendition of the imaged tissue and therefore the image contrast.
Window width
Penetrability of an x-ray beam.
X-ray quality
Output intensity of an x-ray imaging system; measured in roentgens (R).
X-ray quantity