Textbook - Chapter 3 + 4 Flashcards

1
Q

what is interpolation?

A

mathematical method of creating missing data

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the 4 principal components of a computer?

A

input, output, central processing unit and memory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are examples of input devices?

A

keyboard, mouse, touch-sensitive plasma screen, and CT detector mechanism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are examples of output devices?

A

monitor, laser camera, printer and archiving equipment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the cpu?

A

the part of the system that interprets the computer program instructions and sequence tasks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the three principle types of solid-state memory?

A
  1. rom
  2. ram
  3. worm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

which type of solid-state memories are part of the system’s primary memory?

A
  1. rom
  2. ram
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are rom used for?

A
  • imprinted at the factory
  • stores frequently used instructions to start the system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are ram used for?

A
  • has instructions that are frequently changed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

image reconstruction

A

use of raw data to create an image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

attenuation profile

A

system accounting for the attenuation properties of each ray sum and correlating it with the position of the ray

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

ray

A

path the x-ray beam takes from tube to detector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

ray sum

A

detector senses each arriving ray and measure how much of the beam has been attenuated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

views

A

compete set of ray sums

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

back projection

A

compilation of information from all the attenuation profiles to create an image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are some drawbacks to back projection?

A

it produces a streak artifact in a star pattern

17
Q

how do you minimize streak artifacts?

A

filters

18
Q

filters are applied to only ______ data.

A

raw

19
Q

SFOV

A

determines the area that the raw data is acquired

20
Q

out-of-field artifacts

A

when parts of the patient is outside the SFOV causing inaccuracies in the images

21
Q

DFOV

A

section of data selected to be displayed on the image

22
Q

too large DFOV = image to be _______

A

small

23
Q

small images due to too large of a DFOV will result in?

A
  • more data in each pixel = decrease in spatial resolution
24
Q

CT display monitor

A

used to display patient information, scan protocol data, provides many graphic aids to assist in image interpretation

25
Q

DAC

A

digital to analog converters

26
Q

what do DACs do?

A

change the digital signal from computer memory back to analog so the image can be displayed on the monitor

27
Q

multiformat cameras

A

transfers images displayed on monitors to film

28
Q

laser cameras

A

bypasses putting the image onto the display monitor and transfers it directly to the film

29
Q

window width

A

determines the quantity of HUs represented as shades of gray on a specific image

30
Q

if the value is higher than the selected range of the window width, what colour will the object be?

A

white

31
Q

if the value is lower than the selected range of the window width, what colour will the object be?

A

black

32
Q

window level

A

selection of HUs that are displayed on the image

33
Q

what should the window level be set at?

A

a point where the value of the average attenuation number is similar to that of the tissue of interest

34
Q

why is it good practice to widen the window width if a patient is obese or have metallic artifacts?

A
34
Q

what does a wider window width do?

A
  • increases anatomic diversity
  • decreases image contrast
35
Q

what size of window width is good for metallic artifacts and obese patients?

A

wider window widths

36
Q

what size of window width is good for tissues of similar densities like the brain?

A

lower/narrow window widths

37
Q

what does a narrower window width do?

A

provides greater density discrimination and contrast

38
Q

dual window setting

A

when two images of different window widths are superimposed on each other to create a single image