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43 Cards in this Set
- Front
- Back
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Density
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Overall blackness on a radiograph
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Mass Density
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Quantity of matter per unit volume
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Density
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Expressed in Kg/m3
Or Gm/cm3 |
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Mass Density --Per Unit Volume
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•Lung 320 Kg/m3
•Fat 910 Kg/m3 •Muscle 1000 Kg/m3 •Bone 1850 Kg/m3 |
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Mass Density --Per Unit Volume
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•Air 1.3 Kg/m3
•Barium 3500 Kg/m3 •Iodine 4930 Kg/m3 |
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Optical Density
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•Presented on a radiograph from black to clear
•Black numerically equivalent to 3.0 •Clear numerically equivalent to 0.2 |
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Long Scale Contrast
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Lighter film
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Short Scale Contrast
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Darker film
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Optical Density
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Controlled by mAs direct increase
Controlled by SID |
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30 Per Cent Rule
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mAs must be increased by 30% to produce a perceptive increase in optical density
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Density & kVp
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kVp changes affect penetration, but also creates scatter
kVpchanges will also affect PATIENT DOSE & CONSRAST |
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15 Per Cent Rule
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To INCREASE Optical Density by kVp an increase of 15% is equal to DOUBLING the mAs.
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CONTRAST
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The difference in optical densities between adjacent anatomical structures or a variation in optical densities on a radiograph.
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High Contrast
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blacks/whites
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Short Scale Contrast
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blacks/whites
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Low Contrast
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All shades
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Long Scale Contrast
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All shades
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If the x-ray tube is moved closer to the film, the radiation intensity at the film...
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Increases
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What formula tells the radiographer what new mAs to use when the SID changes to maintain film density?
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Maintenance Density Formula
mAs1/mAs2 = D1(squared) / D2 (squared) |
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As the xray tube is moved farther away from the film, the collimator light will ..
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cover a larger area of the film
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The distance between the xray tube and the film is called the ...
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SID Source-image distance
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If the SID doubles, the radiation intensity at the film...
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is reduced by half
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What is the controlling factor of radiographic contrast?
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kVp
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Describe the type of image considered high contrast
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black, white, few shades of gray
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Which contrast scale is also considered high contrast?
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Short Scale
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Which one of these has the most tissue density?
Air, Muscle, Fat or Bone |
Bone
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Which one of these body components whould display the most radiographic density?
Air, Muscle, Fat or Bone |
Air
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The degree of difference between adjacent densities on a radiograph defines...
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contrast
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The radiographic contrast caused by differences in the patient's body is ...
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subject contrast
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Which would absorb more xray photons?
A body component with many electrons or with few electrons |
Many electrons = High Atomic Number
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The ability of a body component to absorb x-rays differently depending on its average atomic number and compactness is called...
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differential absorption
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The reduction in intensity of radiation as it passes through matter is called....
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Attenuation
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If two body components were exactly the same except for their thickness, which compoent would absorb the most radiation? Thicker or thinner body component
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Thicker
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If two body components received the same amount of radiation, which would display the most radiographic intensity? Thicker or thinner body component
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Thinner
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Which one of these can a radiographer usually see on a plain radiograph of the abdomen? the pancreas, liver, spleen or stomach
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Liver
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The addition of which one of these contrast media to the body will decrease the tissue density of the body part? Air, Iodine, or Barium
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Air
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Which one the following contrast media has the highes atomic number? Air, Iodine or Barium
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Iodine
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Which exposure factor give kinetic energy to electrons as they travel from the filament to the anode of the x-ray tube? mA, time, kVp or mAs
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kVp
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An electron that has a lot of kinetic energy as it travels from the filament to the anode of the xray tube will probably produce an xray photon with.. High or low energy
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High Energy
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Which beam would penetrate through body tissues easily? A beam produced with high kVp or low kVp
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High kVp
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Which kVp produces more scatter radiation? High kVp or low kVp
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High kVp
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Which type of image would be produced on a radiograph produced with low kVp? High contrast or low contrast
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High Contrast
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Another term for the presence of scattered radiation on the film is...
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Fog
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