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21 Cards in this Set
- Front
- Back
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Misrepresentation of the size or shape of the structures imaged, independent of visibility (density and contrast) |
Distortion |
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Making objects smaller or larger |
Size distortion |
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Reduced magnification ___ resolution |
Increases |
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To minimize magnification, maximize ___ and minimize ___ |
SID, OID |
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As SID increases, magnification |
Decreases, reduced effect of divergent beam |
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Body parts with an inherently __ OID, are imaged with an __ SID |
Large, increased |
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The __ an object is from the IR the larger it will appear |
Further |
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SID |
Source (target) to image receptor distance |
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OID |
Object to image receptor distance |
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SOD |
Source (target) to object distance |
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A decreased SOD means an ___ entrance skin exposure |
Increase |
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Larger patients will have a ___ SOD |
Decreased |
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Can ___ SID to increases SOD |
Increase |
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What is the magnification factor |
SID/SOD |
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How do you calculate the objects actual size |
o=I/m |
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Unequal magnification of different portions of the same object, the ROI and the IR are not aligned |
Shape distortion |
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Makes the object appear longer than it really is (occurs when tube or IR is off) |
Elongation |
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Appears shorter than it really is (occurs when part is improperly longer up) |
Foreshortening |
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To avoid shape distortion CR should be ___ to ROI & IR |
Perpendicular |
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Long axis of body part should be ___ to IR |
Parallel |
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Which is easier to notice shape or size distortion |
Size |
