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37 Cards in this Set
- Front
- Back
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Controlled primarily by density and contrast |
Visibility of detail |
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Degree of geometric sharpness or accuracy of the structural lines actually recorded in the image |
Recorded detail (detail, definition, sharpness, spacial resolution) |
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Edges/borders of objects sharply defined, small objects adjacent or very close together differentiated |
Criteria of optimal resolution |
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How many dimensions does film have, how many does digital have |
2 dimensions (x&y, horizontal & vertical), 3 dimensions (x,y,&z, voxel Don't just see compression of object you see into it) |
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Goal is to get as much detail as possible while minimizing ___ |
Distortion |
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Allows one to see overall size of an object, allows one to see an objects borders |
Spacial resolution |
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How well the borders of objects are defined, how much of the contrast of the object was recorded |
Special resolution |
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What are the two ways to measure spacial resolution |
Line pairs per millimeter (LP/mm), modulation transfer function (mtf) |
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What is the unit for measuring spacial resolution |
Line pairs per millimeter, lp/mm |
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One line plus one space equals |
1 line |
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The more pairs visible peer mm, the greater the ability to see __ objects |
Smaller |
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Higher the number the __ the resolution |
Better |
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Looks at the accuracy the image when compared to the object, how well did the imaging system replicate the object, sometimes called image "fidelity" |
Modulation transfer function, mtf |
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Measures on a scale from |
0 to 1 |
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Will never reach a MTF of |
1 |
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MTF is calculated by measuring the imaging systems ability to accurately record the objects __ |
Contrast |
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Measurements will vary by objects __ |
Size |
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__ objects will have a higher MTF than __ objects |
Larger, smaller |
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MTF and lp/mm have an __ relationship |
Inverse |
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MTF looks at objects __ |
Contrast |
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lp/mm looks at objects __ |
Edges or contrast changes |
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SOD |
Source (target) to object distance |
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OID |
Object to image receptor |
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SID |
Source (target) to image receptor |
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When OID cannot be reduced what can you do |
Increase SID to compensate |
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As the beam skims the border or edge of an object it created an unsharp shadow called |
Focal spot blur |
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Inner part or area of complete or perfect shadow is the |
Umbra |
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Shadow is called a |
penumbra or focal spot blur |
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When OID is greater, the shadow cast by the angled photon will be able to diverge more before intersecting the IR which caused a |
Larger representation of the object imaged |
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Increased __ reduces the effects of bean divergence |
SID |
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To get maximum accuracy geometrically |
Decrease focal spot size, decrease OID, and increase SID |
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Increase spacial resolution, increase heat load to target, manually selected with lower mA station |
Small focal spot |
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Data picked up from anything other than the primary beam and patient interaction |
Noise |
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What blocks noise and fixes adverse effects |
Computer algorithm |
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Digital data is collected in an on off way what is this called |
Sampling |
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Calculates optimal sampling rate |
Nyquist criterion |
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Artifact is called aliasing (wavy) or described as a __ |
Moire pattern |
