Chapter 8 Exam

Question 1

Which of the following describes the process of radiographic image formation?
a. Beam attenuation
b. Differential absorption
c. Dynamic imaging
d. Ionization

Answer 1

b. Differential absorption

Question 2

X-rays can eject electrons from atoms. This is known as:
a. Beam attenuation
b. Differential absorption
c. Dynamic imaging
d. Ionization

Answer 2

d. Ionization

Question 3

The x-ray interaction with anatomic tissue that is responsible for scattering is:
a. Ionization
b. Photoelectric
c. Compton
d. Absorption

Answer 3

c. Compton

Question 4

Which of the following will increase beam attenuation?
a. Higher kilovoltage
b. Decreasing tissue density
c. Thicker anatomic part
d. Lower atomic number

Answer 4

c. Thicker anatomic part

Question 5

Factors that decrease x-ray absorption include:
a. Increased tissue density
b. Increased x-ray beam quality
c. Increased tissue thickness
d. Increased atomic number

Answer 5

b. Increased x-ray beam quality

Question 6

The range of exposure intensities an image receptor can accurately detect defines:
a. Pixel bit depth
b. Dynamic range
c. Ionization
d. Attenuation

Answer 6

b. Dynamic range

Question 7

Digital image quality is improved with:
a. Larger pixel sizes
b. Smaller pixel bit depths
c. Increased tissue density
d. Larger matrix size

Answer 7

d. Larger matrix size

Question 8

8. Increasing the pixel bit depth will:
   a. Decrease scattering
   b. Increase contrast resolution
   c. Decrease image quality
   d. Increase pixel size

Answer 8

b. Increase contrast resolution

Question 9

What type of imaging system uses an intensifying screen to convert x-rays to visible light?
a. Film-screen
b. Image intensifier
c. Digital
d. Flat-panel detector

Answer 9

a. Film-screen

Question 10

Film-screen imaging has a wider dynamic range than digital imaging
a. True
b. False

Answer 10

b. False

Question 11

Dynamic imaging of internal structures can be visualized with a/an:
a. Image intensifier
b. Flat panel detector
c. Film-screen
d. a and b

Answer 11

d. a and b

Question 12

The process of differential absorption to form an image is the same for digital, film-screen, and fluoroscopy
a. True
b. False

Answer 12

a. True

Question 13

What device receives the x-rays?

Answer 13

image receptor

Question 14

What are the “steps” to producing an x-ray image? (after x-ray production)

Answer 14

• Image receptor can accurately detect a wide dynamic range of exposure intensities
• Anatomic areas of widely different attenuation such as soft tissues and bony structures can be more easily visualized because of the wider dynamic range

Question 15

• Number of bits that determines the amount of precision in digitizing the analog signal and therefore the number of shades of gray that can be displayed in the image
• Determines the shades of gray displayed on the monitor
• Calculated as 2^n

Answer 15

bit depth

Question 16

A combination of rows and columns, of small, usually square “picture elements” called pixels (how the digital image is displayed)

Answer 16

matrix

Question 17

The range of exposure intensities an image receptor can accurately detect

Answer 17

wide dynamic range

Question 18

For a given FOV, increasing the matrix size will _______ the pixel size and _______ image quality

Answer 18

decrease, increase

Question 19

For a given FOV, decreasing the matrix size will _______ the pixel size and _______ image quality

Answer 19

increases, decrease

Question 20

The amount of pixels in the image, size of the matrix

Answer 20

Pixel density

Question 21

the difference between the x-ray photons that are absorbed photoelectrically and those that penetrate the body

Answer 21

Differential absorption

Question 22

the reduction in the energy or number of photons in the primary x-ray beam.
- two processes occur: absorption and scattering

Answer 22

Attenuation

Question 23

the removal of electrons from the inner shell and filling it with the outer shells. Is responsible for total absorption of the incoming x-ray photon.
- occur throughout the diagnostic range 20 kVp-120kVp

Answer 23

Photoelectric absorption (effect)

Question 24

doesn’t provide useful information to the image, it diminishes the contrast (outer shell)

Answer 24

Compton scatter

Question 25

What happens to PE and Compton as we increase kVp?

Answer 25

PE absorption decreases sharply Compton scatter remains proportionally greater

Question 26

What would a high Z# part look like on a good radiograph?

Answer 26

It would appear white

Question 27

matter per unit volume (or the compactness of the atomic particles composing the anatomic part) also affects the amount of beam attenuation

Answer 27

Tissue density

Question 28

Increasing density = ________ attenuation & absorption, ________ transmission

Answer 28

increases, decreases

Question 29

Decreasing density = ________ transmission, ________ attenuation & absorption

Answer 29

increases, decreases

Question 30

The atomic number of the anatomic part and its tissue density affect _____ _____ _________

Answer 30

x-ray beam attenuation

Question 31

Bone attenuates x-ray beam more than _______

Answer 31

muscle

Question 32

Muscle attenuates the x-ray beam more than ______

Answer 32

fat

Question 33

Fat attenuates the x-ray beam more than _____

Answer 33

air

Question 34

the thicker the atomic part, the more x-rays are needed to produce a radiographic image

Answer 34

Tissue thickness

Question 35

Increasing thickness = _______ attenuation & absorption, _______ transmission

Answer 35

increases, decreases

Question 36

Decreasing density = _______ transmission, _______ attenuation & absorption

Answer 36

increases, decreases

Question 37

1. incident photon interacts with an K or L shell electron, gives all of its energy to the ejected electron, photon is absorbed 2. Ejected electron imparts atom with energy equal to excess binding energy 3. The vacancy in K or L shell is filled by an electron from the next orbital shell (cascade effect) 4. As electron drops to fill the void is sheds its excess energy as a secondary photon

Answer 37

photoelectric effect

Question 38

1. Photon ejects outer shell electron 2. The ejected electron leaves atom with equal energy to the excess imparted by the photon 3. The photon continues on an altered path, with less energy (longer wavelength) than before collision

Answer 38

compton effect

Question 39

Comes from excess energy shed by electron dropping to fill void of inner orbital shell

Answer 39

secondary photon

Question 40

half value layer (HVL)

Answer 40

For every 4-5 cm of tissue, the number of photons decreases by half

Question 41

comes from scattered photons from the compton effect, diminishes contrast

Answer 41

Image fog Unwanted exposure to the image receptor

Question 42

When the attenuated x-ray beam leaves the patient, is composed of both transmitted and scattered radiation

Answer 42

Remnant radiation (exit)

Question 43

the invisible image that exists on the exposed film before it is chemically processed

Answer 43

latent image

Question 44

is the visible image on the exposed film after processing

Answer 44

Manifest image

Question 45

dynamic imaging of internal structures can be visualized with a/an: a. film-screen b. projection image c. spot film d. fluoroscopy

Answer 45

d. fluoroscopy

Question 46

total absorption of the incoming x-ray photon is the result of the photoelectric effect a. true b. false

Answer 46

a. true

Question 47

which of the following will decrease beam attenuation? a. increased tissue density b. lower kilovoltage c. higher z# d. higher kilovoltage

Answer 47

d. higher kilovoltage

Question 48

contrast resolution is the ability of the imaging system to represent 2 different structures with the same level of gray a. true b. false

Answer 48

b. false

Question 49

the spatial resolution of a digital image is determined by the pixel size a. true b. false

Answer 49

a. true