Chapter 2 image analysis
Computed Radiography -
Uses cassettes that are placed in the bucky or on the table to obtain projection.
LUT -
Look up table
Histogram formation -
Represents the subject contrasting the remnant radiation and is determined by the mAs and
kVp to create the image.
S1 -
Represents the minimum gray shade value
S2 -
Represents the maximum useful value
Automatic rescaling -
Ideal histogram for every radio graphic projection.
What happens if the images histogram is positioned more to the right? -
Would move the obtained values of each pixel to the left, brightening up the image. Darker
shades of gray
What happens if the image histogram is positioned more to the left? -
Lighter shades of gray.
Move the obtained values of each pixel to the right.
Decreasing the brightness
What happens if the histogram was wider than the LUT? -
Increase the contrast
Narrow the histogram
What happens if the was narrower than the LUT? -
Widen the histogram
Lower the contrast.
Exposure indicators -
Readings that denote the amount of radiation intensity (quantity of photons) that struck the
IR.
EI reading -
Is read at the midpoint of the VOI. ( halfway between S1 s2.)
Midpoint represents? -
