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RAD 121 - PST 2
flashcards for RAD 121
Question | Answer |
---|---|
What is the ability of an imaging system to sharply define an edge called? | acutance (part of spatial resolution) |
***The three factors that influence geometric sharpness are called _____, _____ and _____. | SID, OID, and FSS |
State the formula to calculate geometric unsharpness. | P = FSS x OID / SOD |
State the formula to calculate the Magnification Factor based on distances. | MF = SID / SOD |
State the formula to calculate the Magnification Factor based on object and image. | MF = IW / OW or MF = IW / OW = SID / SOD |
State the formula to calculate the percentage of magnification based on distance. | % magnification = SID - SOD / SOD x 100 |
State the formula to calculate the percentage of magnification based on object and image: | % magnification = IW - OW / OW x 100 |
State the formula to calculate Grid Ratio | GR = Height of lead strips / distance between lead strips |
What is acutance? | a measure of steepness or abruptness of an edge in a photographic image |
What is Ceiszynski's Law? | an isometric angle, equal to 1/2 of the angle formed between the object and IR, will eliminate or minimize distortion (think AP Sacrum) |
What is another name for the geometric unsharpness formula? | Penumbra formula |
What is penumbra? | The region of partial illumination or radiation caused by x-rays not originating from the point source; also called geometric unsharpness. |
What is distortion? | Any misrepresentation of size/shape of object being imaged. |
Name the types of distortion. | A) Size distortion B) Shape distortion |