Digital Imaging Review

Question 1

What term describes the smallest unit of info within a digital image?

Answer 1

picture element (Pixel)

Question 2

What term describes the component of digital radiography receptors responsible for capturing the radiation signal transmitted through the patient

Answer 2

Detector Element (DEL)

Question 3

What term describes the light-emitting components within display monitors

Answer 3

picture element (pixel)

Question 4

When the matrix size of a digital image increases, the size of the individual pixels (increases/decreases)

Answer 4

decreases

Question 5

When the matrix size of a digital image increases, the size of the pixels within the image (increase/decrease)

Answer 5

decrease

Question 6

As the matrix size of a digital image increases, the pixel size (increases/decreases)

Answer 6

decreases

Question 7

When the matrix size of a digital image decreases, the size of the pixels within the image (increase/decrease)

Answer 7

increases

Question 8

How does increased matrix size affect the spatial resolution of a digital image?

Answer 8

increases spatial resolution

Question 9

How does decreased matrix size affect the spatial resolution of a digital image?

Answer 9

decreases spatial resolution

Question 10

Which would be the matrix size associated with the highest spatial resolution?

256x256
1024x1024
2048x2048

Answer 10

2048 x 2048

Question 11

What makes up the digital matrix of the image file?

Answer 11

pixels

Question 12

Within digital radiography image matrix, 1024 x 1024 refers to what?

Answer 12

number of pixels in the matrix

matrix size

Question 13

What radiographic matrix would create an image with the smallest pixels?

512x512
1024x1024
2048x2048

Answer 13

2048 x 2048

Question 14

What variables of a matrix affect spatial resolution?

Answer 14

pixel size
matrix size

Question 14

A larger matrix size would create a more (clear/pixelated) image

Answer 14

clear

Question 15

Which spatial frequency would produce the greatest spatial resolution?

1.12 lp/mm
4.15 lp/mm
6.30 lp/mm

Answer 15

6.30 lp/mm

Question 16

How to calculate pixel size…

Answer 16

pixel size = FOV / Matrix size

FOV (field of view)

Question 17

How to calculate spatial frequency?

Answer 17

SF = 1 / (2 x pixel size)

Question 18

Define dynamic range in radiography?

Answer 18

range of exposures that can be captured by an image receptor (IR)

Question 19

Exposure latitude is defined as…

Answer 19

range of exposure that produces quality images at an appropriate patient dose

Question 20

The specifications for an xray imaging system indicate that the detector can capture exposure values from 0.1 microgray to 1000 microgray. This quality of the system is called…

Answer 20

dynamic range

Question 21

Consider an xray exposure that results in a receptor exposure of 0.001 microgray, the resulting image is expected to display what? and why?

Answer 21

quantum mottle

detector has not received enough information to create a quality image

Question 22

An xray exposure above the highest level of the exposure latitude may result in an image error called…

Answer 22

saturation artifact

Question 23

Define exposure latitude

Answer 23

ability to produce radiographs at a wide range of technical factors

Question 24

A radiographer acquires an optimal image of the wrist using 60 kvp and 2.5 mAs. Acquiring the same projection of 72 kvp and 5 mAs will result in what?

Answer 24

excessive patient dose

Question 25

Consider this scenario: One radiographer acquires an image of the chest using 100 kvp and 2 mAs. A different tech acquires an image of the chest of the same patient using 120 kvp and 2.5 mas. Both exposures result in EI that were acceptable. This is an example of...

Answer 25

exposure latitude

Question 26

What characteristics are present on an xray that was taken using a too low exposure setting?

Answer 26

quantum mottle grainy

Question 27

Define bit depth

Answer 27

total number of brightness levels that can be produced by the digital system

Question 28

How many shades of gray can be displayed on a 8-bit digital radiography system?

Answer 28

256 shades

Question 29

Calculate shades of gray from bit depth

Answer 29

2^n where n = bit depth

Question 30

Higher bit depth allows for (greater/less) amount of anatomic information on an image

Answer 30

greater

Question 31

quantization is a digital radiography process through which receptor reading are...

Answer 31

converted to specific digital values

Question 32

Higher contrast resolution means (more/less) shades of gray

Answer 32

more

Question 33

during digital image formation and processing, quantization takes place where

Answer 33

analog to digital converter (ADC)

Question 34

What is the smallest exposure diference that can be detected and displayed by the imaging system?

Answer 34

contrast resolution

Question 35

What factor influence the grayscale of a digital radiograph

Answer 35

bit depth

Question 36

As window level increases, brightness _______

Answer 36

increases

Question 37

The range of exposures a digital system can retain and use to create the image is the _________

Answer 37

dynamic range

Question 38

Quantum mottle on a digital image is caused by insufficient ___ ____

Answer 38

photon quantity

Question 39

T/F If a digital image is overexposed it must always be repeated.

Answer 39

false

Question 40

As you narrow the window width, you will create a _____ (longer/shorter) scale of contrast.

Answer 40

shorter

Question 41

Grayscale on a digital system is another way of describing the ____

Answer 41

scale of contrast

Question 42

number of pixels to create an image is the _____

Answer 42

matrix size

Question 43

T/F The use of a digital imaging system affects the process that creates size and shape distortion.

Answer 43

False

Question 44

T/F The digital imaging system is more sensitive to artifact material.

Answer 44

True

Question 45

A larger matrix will have ____ (smaller/larger) pixels, meaning the pixel pitch is (smaller, larger)

Answer 45

smaller, smaller

Question 46

A wide window width on an image will make it look more black/white or gray/white

Answer 46

black/white

Question 47

The ratio of radiation exposure to noise captured on an image is _____

Answer 47

signal to noise ratio

Question 48

T/F Monitor quality will affect spatial resolution of an image

Answer 48

true

Question 49

The relationship between spatial frequency and modulation transfer function is (indirect/direct)

Answer 49

indirect

Question 50

The ____ determines the amount of gray shades the system is able to display on the digital image

Answer 50

bit depth

Question 51

Pixel pitch, pixel size, and pixel density all have an affect on _______

Answer 51

spatial resolution

Question 52

What is "signal" referring to or describing?

Answer 52

useful information captured from the remnant beam Patient's actual anatomy

Question 53

Blotchy appearance caused by insufficient number of photons reaching the image receptor is known as ..... (3)

Answer 53

quantum noise quantum mottle photon starvation

Question 54

What would reduce system noise?

Answer 54

proper upkeep/maintenance of equipment

Question 55

What type of noise cannot be reduced and is always present/constant?

Answer 55

ambient noise

Question 56

Increasing the kvp would (increase/decrease) the signal and (increase/decrease) the scatter reaching the IR.

Answer 56

increase, increase

Question 57

Photons that add information but do not represent the anatomic structures are considered....

Answer 57

scatter radiation

Question 58

When using a grid is it preferred to increase kvp or mas

Answer 58

mas