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46 Cards in this Set
- Front
- Back
define radiographic artifacts
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anything that decreases the quality of the radiograph
any density not caused by proper shadowing of the object in the primary beam |
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How do you evaluate film quality (what factors do you evaluate)
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exposure
positioning labeling centering collimation development/ processing artifacts |
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This is an example of a non-diagnostic study due to overexposure
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focal increased radioopacity in the disc space at L5-L6 IV disc space
due to debris on intensifying screen |
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poor quality radiographs can result in
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non-dx study
missed or incorrect dx excessive radiation exposure increased cost to clinic & client |
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What is the first thing you should look for when first evaluating an image
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evaluate film quality and identify artifacts
are the necessary items included? is the film the correct density? are the images clear? |
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once you have identified an artifact, what should you ask yourself
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generalized or localized?
phase of image production - prior to exposure - during exposure - during or after processing |
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what are some of the common generalized artifacts
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decreased film density
poor contrast (film fog) grid cutoff off-collimation image off-center increased film density motion unevenly developed kissing defect double exposure |
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increased film density (film too dark)
overexposure - technique too high (kVp, mA/ exposure time too long) - use of grid technique w/o using a grid - overestimation of thickness of the part to be examined double exposures decreased focal-film distance increased developer time or developer temp too high decreased focal-film dist - decreasing the dist b/w the xray tube and the patient surface increases the concentration of radiation thus creating a darker radiograph |
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underexposure (decreased film density)
technique too low - low kVp, mA - exposure time too short increased focal film dist improper use of a slower film screen combination - improper film for type of intensifying screen underestimation of patient thickness or density decreased developer time or low developer temp failure to hold exposure switch closed for the length of the exposure time loading 2 films in a cassette |
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loss of contrast (fog)
- pressure (stacking boxes in storage area) - heat/ humidity (should be stored <68 deg F; 30-50% humidity) - light (safelight in darkroom might be too close to film, wrong spectrum of light for film, film exposed to safelight for too long, darkroom not light tight) - chemical exposure (increased developing time due to exhausted developer, gasses such as formaldehyde in storage area) - old film - scattered radiation (storing cassettes in xray room, leaning on wall in room during second exposure with a diff cassette) |
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how do you account for scatter radiation
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scatter increases with
- thickness of patient - kVp setting - field size corrections - use grid for anything over 10 cm - use appropriate kVp - collimate |
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why does a properly positioned grid matter
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grid allows most of the primary radiation to reach the film and absorbs scatter radiation that is not parallel with the grid
- you have to increase mAs to compensate for decrease in primary beam malpositioned grid - blocks the primary beam to a greater degree than expected - causes uniform loss of primary radiation across the entire surface of the grid - lateral decentered grid - off level grid upside down grid - extreme loss of primary radiation at the periphery, with near norm transmission at the center - underexposure of edges |
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malpositioned grid
xray tube is off center in relation to grid |
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upside down grid
underexposed edges (notice the bands in the underexposed areas) |
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double exposure
2 separate images in the film with generalized overexposed, dark film |
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double exposure
2 separate images in the film with generalized overexposed, dark film |
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double exposure
due to accidental double click 2 images slightly overlapping each other - more maxillary canines than norm - really dark film |
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motion artifact
motion assoc with patient, tube, or cassette SOLUTIONS proper chemical &/or physical restraint - buprenex can cause panting so hard to get good film use fast screen film avoid hand holding cassettes shorter exposure time - increase mA |
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film unevenly developed
chemicals not stirred white streaky patter over the entire film |
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improper rinsing of film
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chemical stains
developer not rinsed and streaks down film |
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kissing defect
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localized area of increased density due to light leak
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light leak
film exposed to light along the edge (likely while in storage bin) check other films in that package |
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light leak
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cassette not properly closed
allowed light to expose the corner of the film also less image sharpness next to light leak poor screen to film contact due to the cassette not being properly closed |
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localized artifact
bending film |
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mult crescent shaped artifacts caused by bending of the film
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static electricity
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static electricity
- smudge pattern |
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radioopaque material on left leg = surface debris
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skin fold "artifact"
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ET tube and esophageal stethoscope
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ECG clips and lines
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cast material causes a fuzzy appearance & decreases quality of the rad
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malpositioning
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malpositioning
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how to fail 4th yr radiology
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how do you fail 4th year radiology
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improper LUT assignment
using abd setting when imaging thorax |
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quantum mottle
due to too few incident xrays striking the imaging plate (not enough xray input or excessive attenuation - patient or grid) result - grainy, pixilated, mottled image correction - increase technique and retake image (provides the imaging plate with more info) |
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parital erasure
see previous image in background that remains due to incomplete erasure of the previous image from the digital plate |
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paradoxical overexposure
due to extreme overexposure only most highly attenuated areas are displaced in norm gray scale corrected by decreasing technique |
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Überschwinger artifact
this is norm with how the computer interprets the film (don't mistake for motion/ implant failure) Thin black line along extremely radiopaque objects Mimics lucent area seen with loosening/movement or infection around orthopedic devices Decrease the artifact by controlling frequency spectrum of image |
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MOIRE
Results from using a low frequency grid with digital imaging |