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22 Cards in this Set
- Front
- Back
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If you increase the kVp by 15% and decrease the mAs by half, the blackness will stay the same, but what changes?
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Decreased contrast/ latitude (greys and whites)
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How does an underexposed film appear?
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Clear
Overexposed=black |
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What are 3 ways technique can be corrected for underexposed radiographs?
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1) Quadruple the mAs
2) Increasing kVP by 15% two times 3) Double the mAs and increase kVp by 15% |
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What are 3 ways to correct an overexposed radiograph?
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1) mAs should be decreased by a factor of 2 or 4
2) kVp decreased by 15% twice 3) halve the mAs and kVp decreased by 15% |
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What is the inverse term for contrast?
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Latitude
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What is the contrast and latitude of high kVp films?
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low contrast, high latitude
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What parts of the body should you use high speed systems for? low speed systems?
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High speed: thorax and abdomen (high motion areas)
Low speed: extremities |
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What are 5 processing artifacts?
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1) Under-development
2) Over-development 3) Under-fixation 4) Over-fixation 5) Incomplete mixing of chemical |
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What is the cause of under-development?
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Insufficient development time or developer at too high a temperature
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What is the effect of under-development?
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Films that are too "light" i.e. appear to be underexposed w/ decreased contrast
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What is the cause of over-development?
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Too long a development time or developer at too high a temperature.
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What is the effect of over-development?
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Films that are too "dark" i.e. appear to be overexposed or fogged
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What is the cause of under-fixation?
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Too short a fixation time, or exhausted chemicals
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What is the effect of under-fixation?
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Films have a brown tint and are cloudy or milky in appearance; over time will also become over-developed as ionic silver is slowly converted to atomic silver
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What is the cause of over-fixation?
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Too long a fixation time, or failure to wash films after fixation
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What is the effect of over-fixation/
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Films that eventually turns yellow-brown due to buildup of silver sulfide
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What is the effect of incomplete mixing of chemicals during film processing?
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Causes a "marbled" appearance due to non-uniform concentration of developer
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What are 2 artifacts that can occur prior to film exposure?
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1) Film handling problems
2) Film fog |
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What are 2 film handling problems?
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1) Static electricity-light from static exposes film
2) Pressure artifacts-film crystals are sensitive to pressure |
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What are 2 causes of film fog?
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1) Exposure to light-black areas
2) Film stored in excessive temperature, humidity or pressure |
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What are 6 artifacts that can occur at the time of exposure?
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1) Multiple exposures
2) Patient motion 3) Objects other than the patient b/w x-ray tube and cassette 4) Grid artifacts-grid cut off 5) Tube mal-positioning -only part of film is exposed 6) Casette problems (dirty, cracked) |
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What are 4 artifacts that can occur after exposure?
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1) Film handling problems
2) Fog 3) Processing artifacts 4) Digital film artifacts |
