LESSON 2.2

Question 1

A digital image is made up of a two-dimensional array of numbers

consists of columns (M) and rows (N) that define small square regions called picture elements or pixels

Answer 1

MATRIX

Question 2

The amount of body part or patient included in the image.

The larger the FOV, the more area is imaged

Answer 2

Field of View (FOV)

Question 3

Is the smallest element in a digital image.

Answer 3

Pixel, or picture element

Question 4

The size of the pixel is directly related to the amount of spatial resolution or detail in the image

Answer 4

PIXEL SIZE

Question 5

The number of bits within a pixel

Most digital imaging systems have bit depths of 10 to 16, resulting in more shades of gray

Answer 5

Pixel Bit Depth

Question 6

Refers to its appearance on the display monitor of the computer and is a function of the monitor’s ability to emit light through the surface of the display.

Answer 6

Brightness

Question 7

The ability of the digital system to display subtle changes in the shade of gray.

Answer 7

Contrast Resolution

Question 8

The ability of the imaging system to demonstrate small details of an object

Answer 8

Spatial Resolution

Question 9

Image noise contributes no useful diagnostic information and serves only to detract from the quality of the image.

visible as brightness or density fluctuations on the image.

Answer 9

Quantum Noise

Question 10

Ability to respond to varying levels of exposure, more tissue densities on the digital image are seen, giving the appearance of more detail.

Answer 10

Dynamic Range

Question 11

The purpose of this class of processing is to generate an image that is more pleasing to the observer

Answer 11

Image Enhancement

Question 11

The range of exposure diagnostic image values the image detector is able to produce.

Dependent on the image detector—the higher the dynamic range of the detector, the more values can be detected

Answer 11

Exposure Latitude

Question 12

These processing operations “create images from other images or non-image data.

Answer 12

Image Synthesis

Question 12

The purpose of image restoration is to improve the quality of images that have distortions or degradations

Answer 12

Image Restoration

Question 13

When the frequencies of areas of interest are known, those frequencies can be amplified and other frequencies suppressed.

Also known as high-pass filtering and increases contrast and edge enhancement.

Answer 13

Edge enhancement

Question 13

The purpose of image compression of digital images is to reduce the size of the image in order to decrease transmission time and reduce storage space.

Answer 13

Image Compression

Question 14

Also known as low-pass filtering
Occurs by averaging each pixel’s frequency with surrounding pixel values to remove high-frequency noise.
The result is a reduction of noise and contrast.

Answer 14

Smoothing

Question 15

The process of adding text to an image

Answer 15

Annotation

Question 16

controls how bright or dark the screen image

Answer 16

window level

Question 17

controls the ratio of black and white, or contrast

Answer 17

window width

Question 18

Blacken out the white collimation borders, effectively eliminating veil glare

Answer 18

Background Removal or Shuttering

Question 19

Results in a black appearance of bone and a white appearance of soft tissue

Answer 19

Image Inversion

Question 20

Technique that can remove superimposed structures so that the anatomic area of interest becomes more visible.

Answer 20

Digital Subtraction

Question 21

When anatomy or the area of interest is too large to fit on one cassette, multiple images can be “stitched” together using specialized software programs

Answer 21

Image Stitching

Question 21

One of the most commonly used three-dimensional (3D) rendering techniques.

When doing a CT scan of a patient, thin axial slices can be acquired of a volume of tissue.

The slices can then be loaded into the MPR software, and a reconstruction in another plane can be produced

Answer 21

Multiplanar Reconstruction (MPR)

Question 21

Used to visualize vessels

Answer 21

Maximum Intensity Projection (MIP)

Question 21

used to visualize air-filled structures

Answer 21

Minimum Intensity Projection

Question 22

Using a threshold of pixel intensity values, everything below the threshold will be removed, and everything above will be assigned a color and shown as a 3D object

Answer 22

Shaded Surface Display (SSD)

Question 23

Similar to MIP but allows the user to assign colors based on the intensity of the tissue so that bone, contrast agent, and organs can be seen in different colors.

The technique uses a histogram-type graph to differentiate the various structures

Answer 23

Volume Rendering Technique (VRT)