worksheet 2

Does shuttering the digital image reduce the exposure to the patient?

False

Does window width control the brightness of the image on the display?

False

Is the look-up table used to determine the brightness and contrast unique for each anatomic part?

True

What is a graphical representation of a digital image called?

Histogram

What does window level control?

Brightness

In preprocessing, how does the computer adjust for dead pixels?

Kernelling

Which of the following is not a postprocessing option?

Dynamic range compression

What causes aliasing?

Insufficient sampling frequency

What is saturation?

When dels have reached their maximum electrical charge and are pure black

What type of histogram analysis would be used for a pelvis x-ray?

Type 3

Which of the following controls the length of the gray scale of a displayed image?

Window width

Which of the following is an example of postprocessing?

Windowing and resizing

What can throw a histogram analysis off?

Selecting the wrong part for the exam, in CR, not evenly spacing when multiple images are imaged, and artifacts

What does LUT stand for?

Look-up table

Put processing steps in order: Values of interest → Histogram → Look up table

2,1,3

What would you do to see the edge of the bones during postprocessing?

Apply edge enhancement

What are the three types of postprocessing domains?

Spatial, intensity, frequency

Does smoothing increase the visible appearance of noise?

False

Are lead markers recommended for legal reasons despite electronic markers being available?

True

How is the speed of any imaging system related to exposure required?

Inversely

Can nearly all modern CR and DR systems be operated without substantial noise/mottle in the image?

True

When should a dark digital image not be repeated?

Unless saturation has occurred

What happens to the range available to the radiologist when windowing is applied and saved to PACS?

Reduced/limited/narrowed

What do smoothing algorithms suppress?

Moderate amounts of noise/mottle

What may smoothing lead to in an image with low contrast?

Loss of detail

What may edge enhancement increase in a high-contrast image?

Noise

What type of software is used for aligning images in a scoliosis series?

Stitching

In which domain do point, area, and global processing occur?

Spatial

In which domain is the image sorted by pixel values?

Intensity

What type of processing is zoom/magnification?

Area

What are the two columns of a look-up table?

Input and output

What can occur if dynamic range is limited?

Clipping

In which domain can detail processing be performed?

Spatial or frequency

What passes a smaller sub-matrix over each pixel during kernel operations?

Kernel

What is a form of low-pass filtering that softens edges and reduces noise?

Smoothing