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104 Cards in this Set
- Front
- Back
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Geometric properties
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refer to the sharpness of structural lines recorded in the radiographic image
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Recorded detail
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refers to the distinctness or sharpness of the structural lines that make up the recorded image
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Resolution
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is the ability of the imaging system to resolve or distinguish between two adjacent structures
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Spatial resolution
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refers to the smallest detail that can be detected in an image
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Contrast resolution
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refers to the ability of the imaging system to distingush between small objects having similar subject contrast
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Distortion
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results from the radiographic misrepresentation of either size(magnification)or shape of the anatomic part
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The faster the _____ _____ the more detail we lose.
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relative speed
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True or False. Poor film screen contact will cause decreased unsharpness.
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False. Increased unsharpness.
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_______ is the ability to distinguish two adjacent details as being seperate from one another.
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Resolution
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What do the black lines on a resolution test pattern represent?
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air
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What do the white lines on a resolution test pattern represent?
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lead
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True or False. The smaller the test line the better the resolution.
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True
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What is a device used to record and measure line pairs?
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Resolution Test Pattern
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Resolution is expressed in the unit of what?
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Line pairs per millimeter. LP/mm
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______ resolution refers to the smallest detail that can be detected in an image.
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Spatial
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True or False. Digital imaging systems have excellent spatial resolution.
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False. Film screen imaging systems have excellent spatial resolution.
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______ resolution refers to the ability of the system to distinguish between small objects having similar subject contrast.
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Contrast.
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What type of systems have better contrast resolution?
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Digital imaging systems
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Film screen imaging systems have excellent ______ resolution.
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spatial
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The most detrimental affect on recorded detail of the image is caused by what?
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Motion Unsharpness
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Motion of what four factors greatly decreases recorded detail?
A)tube B)technician C)patient D)part E)image receptor |
A)tube, C)patient, D)part, E)image receptor
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What is the unsharpness resulting from patient motion known as?
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blur
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True or False. There is only one type of patient motion.
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False. There are two.
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What are the two types of patient motion?
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Voluntary (patient's control) and involuntary (not under patient's control).
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What are three things that the tech can do to control patient motion?
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1)Use short exposure times
2)Provide clear instructions 3)Using physical immobilization as deemed necessary |
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_______ results from the radiographic misrepresentation of either the size or shape of the anatomic part
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Distortion
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True or False. When the image is destorted, the recorded detail is increased.
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False. Recorded detail is reduced.
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An increase in the object's image size compared with its true, or actual, size si called what?
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Size distortion/ magnification
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What are the two types of distortion?
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Size and Shape
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Magnification of the true object will occur because there is always some ____ during radiography.
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OID
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True or False. OID is directly related to magnification.
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True
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If OID is decreased, there is ______ magnification and ______ detail.
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decreased and increased
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If OID is increased, there is _______ magnification and _______ detail.
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increased and decreased
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What two factors are involved in the amount of size distortion?
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SID and OID
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True or False. SID has a larger impact on size distortion than OID.
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False. OID has a larger impact.
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As SID increases, size distortion ______
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decreases
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As SID decreases, size distortion ______.
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increases
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A(n) ______ in the amount of unsharpness recorded on the image ______ the contrast of small anatomic structures, thereby ______ the overall visibility of recoreded detail.
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increase; decreases; reducing
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Recorded detail is defined as
A) accuracy of structural lines recorded B) visibility of the structural lines C) misrepresentation of the shape of the structural lines. D) amount of structural lines |
A) accuracy of structural lines recorded
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The relationship between focal spot size and distance results in
A)receptor unsharpness B)motion blur C)geometric unsharpness D)shape distortion |
C)geometric unsharpness
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Increasing the SID will
A)increase unsharpness B)increase distortion C)increase magnification D)increase recorded detail |
D)increase recorded detail
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Decreasing the OID will
A) increase unsharpness B) increase distortion C) increase magnification D) increase recorded detail |
D)increase recorded detail
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The ability of the imaging system to distinguish between two adjacent structures defines
A)blur B)resolution C)distortion D)acuity |
B) resolution
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The amount of unsharpness created using a focal spot of 0.6mm, an SID of 36 inches, and an OID of 3 inches is
A) 0.005 B) 0.055 C) 0.567 D) 0.635 |
B) 0.055
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What is the image size of a part measuring 2.5 cm using an SID of 100 cm (40), an OID of 5 cm, and a focal spot of 1.25 mm?
A) 2.37 cm B) 2.50 cm C) 2.63 cm D) 2.75 cm |
C) 2.63 cm
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Using a larger focal spot size has what effect on the radiographic image?
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Decreases recorded detail
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Shape distortion can be created by doing what?
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Angling the CR
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Which of the following has the most detrimental effect on the recorded detail of the image?
A) Large focal spot size B) Increased OID C) Motion D) Magnification |
C) Motion
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What 3 things should be considered with pediatrics?
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Size, Fast exposure (move a lot), bone density
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the larger the patient the ________ (more/ less) exposure factors needed.
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More
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how much of the population is Sthenic?
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50%
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how much of the population is asthenic?
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10 % (EXTREMELY SLENDER)
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how much of the population is hyposthenic?
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35% (SLENDER, TALLER)
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How much of hte population is Hypersthenic?
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5% (STALKY)
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True/ False:
Pathology does no effect exposure technique in many cases |
False
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additive diseases (increse/ decrease) absorption therefore have to use (more/ less) exposure factors
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increse, more
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True/ False:
distructive diseases are easier to penetrate so will decrease exposure factors. |
True
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True/ False:
som diseases are KVP/ mAs specific |
True
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the radiation- and light-sesitive layer of radiographic film is the ________ layer.
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emulsion
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crossover is a radiographic problem becaue it decreases
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recorded detail
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spectral sensitivity refers to the color sensitivity of
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radiographic film
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according to the gurney-mott theory of latent image formation, electrons liberated by radiation or light exposure are attractged to the
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sensitivity speck
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silver halide crystals are found in the film's
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emulsion
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which of the follwing is most common type of film for general radiographic examinations
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scree, doubl-emulsion
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poor film-screen contact results in loss of
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recorded detail
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the purpose of intensifying screens is to
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decrease patient dose
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the most common phosphor material used in today's intensifying screens is/are:
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rare earth elements
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the speed of an intensifying screen can be reduced by adding:
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dye to the phospor layer
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What is the intensification factor for screens that require 5 mAs to produce the same density as produced by direct exposure using 150 mAs
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30
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if 25 mAs is used with a 500 speed film-screen system to produce an optiml image, how much mAs is needed to produce the same density with a 100 speed system.
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125 mAs
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typically, as screen speed decreases, ________ decreases:
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density
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As the number of silver halide crystals increses, the film sensitivity or speed __________.
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increases
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True/ False:
as the size fo the silver halide crystals increase, the film sensitivity or speed decreases |
false
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The fater the speed of a film the _____(more/ less).
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less
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Spectral sensitivity refers to the color sensitivity of what?
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Radiographic film
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Correctly matching the color sensitivity of the film to the color emission of the intensifying screen......
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Spectral matching
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Most common digital image receptor.......
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(CR)
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Made of plastic and protects the fragile phosphor material beneath it............
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Protective layer
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Is the material that is sensitive to radiation and light..............
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Silver halide
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A chemical compound that emits visible light when struck by radiation........
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Phosphor
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Is the emmission of light from the screen when stimulated by radiation...........
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Luminescence
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Several sensitivity specks with many silver ions attracted to them.............
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Latent image centers
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Silver halide crystals are found in the films what???
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Emulsion
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Two general types of film that are used in diagnostic imaging.............
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Direct-exposure film and Screen film
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The radiation sensitive and light-sensitive layer of the film.............
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emulsion
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Refers to the ability of phosphors to emit visible light only while exposed to x-rays....................
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Fluorescence
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Polyester that gives the film physical stability "final layer"................
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Base layer
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The speed of an intensifying screen can be reduced by adding what
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Dye to phospher layer
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Radiographic film having an emulsion coating on both sides of the base
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Double- emulsion
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Cross over is a radiographic problem because it decreases what?
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Recorded detail
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Is a durable protective layer that is intended to prevent damage to the sensitive emulsion layer underneath it................
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Supercoat
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Generally consists of a light absorbing dye used to absorb light directed toward it by the phospher layer.......
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Absorbing layer
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The color of light produced by a particular intensifying screen............
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Spectal emission
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Constitutes 90% to 99% of silver halide in film emulsions..............
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Silver bromide
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Makes up 1% to 10% of the silver halide in film emulsions.........
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Silver iodide
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Refers to the correctly matching color of light produced by a particular intensifying screen.......
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Spectral matching
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Is the study of the relationship between radiation exposure and the amount of density produced....
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Sensitometry
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Devices found in cassettes that contains phosphers that convert x-ray energy into light, which then exposes the radiographic film.........
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Intensifying Screen
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According to the Gurney-Mott theory of latent image formation, electrons liberated by radiation or light exposure are attracted to what?
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Sensitivity specks
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Screen speed and density are directly proportional. True or False
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True
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Occurs when screen phosphors continue to emit light after the x-ray exposure has stopped..........
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Phosphorescence(undesirable)
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Refers to light that has been produced by an intensifying screen that exposes one emulsion and then crosses over the base layer of the film to expose the other emulsion..........
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Crossover
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Less common digital image receptor............
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(CCD)
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Single emulsion film that is significantly thicker than screen film and requires more development time.........
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Direct-exposure film
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