Lecture 5

Question 1

Histogram analysis looks at the ____ of each pixel & the ____ that the pixel value occurs in the image.

Image data is analyzed and the ______ and _______ values are used to determine the lowest and highest useful exposures based on _________.

Answer 1

value; number of times

minimum (s1); minimum (s2); the anatomy selected

Question 2

1. What is the “S” number?

Answer 2

1. This number represents the numerical value of the exposure received by the image receptor.

Question 3

1. S-values above the range indicates _______.
2. S-values below the range indicates _____,

Answer 3

under exposure; over exposure

Question 4

What are some factors that affect the “S” number?
hint: Some Dogs Can Eat Babies

Answer 4

Scatter
Distance
Collimation
Exposure menu selection
Background radiation

Question 5

What is the range of the L value?

Answer 5

1.6 to 2.3

Question 6

What is exposure data recognition?

Answer 6

An algorithm that searches for the anatomy & identifies the collimated borders and eliminates scatter outside the FOV.

Question 7

What are the four reading modes of exposure data recognition?

Answer 7

Auto, Semi, Semi-X, fixed.

Question 8

Post-processing is done where?

Answer 8

Via a QC workstation.

Question 9

Define contrast manipulation.

Answer 9

Use of contrast enhancement parameters to convert the digital values in an image with the appropriate brightness

Question 10

Window _____ controls contrast and window _____ controls brightness in the digital image.

Wider width = ____ contrast
Higher window level = _______ image.

Answer 10

width; level

lower; darker

Question 11

1. _________________ removes the white unexposed borders around the image.
2. _____________ is used to blacken out the white collimation borders.

Answer 11

1. Background removal
2. Shuttering

Question 12

What is image reformatting?

Answer 12

Adjusting the acquired image (eg. cropping, adding digital annotations)