Deck 8: Image Postprocessing and Visualization Tools

Question 1

Windowing in CT is an example of:

A) a local processing operation.
B) convolution.
C) gray-level mapping.
D) an image reconstruction algorithm.

Answer 1

gray-level mapping.

Question 2

A large WW indicates that there is a relatively ______________ gray scale.

A) long
B) short
C) narrow
D) curved

Answer 2

long

Question 3

Which of the following is a plot of the pixel values as a function of their frequency of occurrence?

A) Region of interest (ROI) statistics
B) CT histogram
C) Highlighting
D) Multiple windowing

Answer 3

CT histogram

Question 4

Gray-level mapping belongs to the class of:

A) point processing technique.
B) local processing technique.
C) global processing technique.
D) geometrical processing technique.

Question 5

Which advanced tool in CT allows users to view a large set of images very quickly?

A) Cine visualization
B) Advanced quantitative measurement
C) Interactive visualization
D) Virtual reality visualization

Question 6

As the WW increases, picture contrast:

A) increases.
B) decreases.
C) remains unchanged.
D) is optimized to show the specific anatomical structures.

Question 7

In which of the following are pixels in a certain region of the image made to appear brighter?

A) Highlighting
B) Image magnification
C) ROI transfer
D) Point-to-point imaging

Question 8

Which of the following are not categories of three-dimensional rendering?

A) Surface-shaded display
B) Volume rendering
C) Maximum and minimum intensity projections
D) Windowing

Question 9

The WL in CT is the:

A) center of a range of CT numbers.
B) pixel depth.
C) range of CT numbers.
D) center of the CT matrix.

Question 10

Which of the following basic visualization tools allows for the mean and standard deviation within a given ROI?

A) ROI statistics
B) CT histogram
C) Highlighting
D) Multiple windowing

Question 11

Which of the following generates sagittal, coronal, and paraxial images from transaxial slices?

A) Back-projection reconstruction
B) FBP reconstruction
C) Multiplanar reconstruction
D) Radiation treatment planning CT

Question 12

Which of the following controls the contrast of the CT image?

A) Peak kilovoltage (kVp)
B) Milliamperage
C) WL
D) WW

Question 13

One industry standard in data transfer and connectivity is:

A) Digital Imaging and Communications in Medicine (DICOM).
B) hospital information system.
C) radiology information system.
D) picture archiving and communications system.

Question 14

What happens to a CT image when the WL moves toward the lower CT numbers?

A) Appears darker
B) Appears white
C) Longer gray scale
D) Shorter gray scale

Question 15

Which of the following optimizes the image display for a particular structure?

A) kVp
B) Milliamperage
C) WW
D) WL

Question 16

The WW in CT is the:

A) center of a range of CT numbers.
B) pixel depth.
C) range of CT numbers.
D) dimension of the matrix.

Question 17

If the WW setting is 200 and the WL is 0, which of the following occurs?

A) CT numbers greater than +100 appear white
B) CT numbers less than 100 appear gray
C) CT numbers between 0 and +200 appear black
D) Only those numbers between +100 and +200 appear gray

Question 18

Which of the following belongs to the class of nonlinear image manipulation techniques?

A) Image enhancement
B) Image smoothing
C) Gray-scale manipulation
D) Linear smoothing

Question 19

Which of the following determines the maximum number of gray shades to be displayed on the television monitor?

A) Window level (WL)
B) Window width (WW)
C) Contrast controls on the television monitor
D) Filtered back-projection (FBP) algorithm

Question 20

An examination of the abdomen has a WW of 400 and a WL of 0. Which of the following is true given these settings?

A) All structures between -200 and 200 will spread through the gray scale
B) All structures between -200 and 200 will be white
C) All structures between -200 and 200 will be black
D) Only those structures above 400 will have different shades of gray

Question 21

The created multiplanar reconstruction images are poorer in quality than the obtained transaxial images.

Question 22

Through the manipulation of CT numbers of the various tissues, the picture can be changed to show soft tissues and dense structures such as bone.

Question 23

The CT number for water is +1000.

Question 24

A narrow WW implies that the transition from black to white will take place over a wide range of CT numbers.

Question 25

Coronal multiplanar reconstructions allow the observer to view the images in an anterior to posterior plane.

Question 26

A WL of -150 Hounsfield units (HU) is appropriate for viewing the lungs.

Question 27

A large WW means a long gray scale.

Question 28

Windowing does not make use of the CT numbers.

Question 29

Image smoothing is an example of a linear image manipulation technique.

Question 30

The range of CT numbers is the WL.

Question 31

When the WL is centered on the lungs, the image display is optimized for the lungs.

Question 32

Preset window settings allow CT scanners to simultaneously display two different density ranges (different WW and WL) in order to define two different anatomic areas.

Question 33

Windowing is the most common image processing technique in CT.

Question 34

Windowing is an example of a linear image manipulation technique.

Question 35

Multiplanar reconstruction creates three-dimensional images from the transaxial data set.