Chapter 9 Exam

Question 1

A quality radiograph must include:
a. Accuracy of structural lines displayed
b. Minimal sharpness
c. Visibility of anatomic structures
d. All of the above

Answer 1

d. All of the above

Question 2

Visibility factors of a quality radiograph include:
a. Brightness
b. Spatial resolution
c. Contrast
d. a and c

Answer 2

d. a and c

Question 3

Which of the following results in a poor-quality digital image because of improper processing due to extreme over exposure to the image receptor
a. Distortion
b. Saturation
c. Quantum noise
d. Modulation transfer function

Answer 3

b. Saturation

Question 4

What feature provides a numeric value indicating the level of radiation exposure to the digital image receptor?
a. Exposure indicator
b. Saturation
c. Pixel density
d. Grayscale

Answer 4

a. Exposure indicator

Question 5

Anatomic tissues that attenuate the x-ray beam equally are said to have:
a. Quantum noise
b. High contrast
c. Low subject contrast
d. Less unsharpness

Answer 5

c. Low subject contrast

Question 6

An imaging system that can resolve 10 Lp/mm instead of 6 Lp/mm is said to have:
a. Less distortion
b. More unsharpness
c. More distortion
d. Improved sharpness

Answer 6

d. Improved sharpness

Question 7

Unwanted scatter exposure to the image receptor will likely increase:
a. Unsharpness
b. Brightness
c. Fog
d. Saturation

Answer 7

c. Fog

Question 8

What is defined as “the range of exposure intensities an image receptor can accurately detect”?
a. Resolution
b. Contrast
c. Window level
d. Dynamic range

Answer 8

d. Dynamic range

Question 9

For a given field of view (FOV), a _____ matrix size will result in _____ pixels
a. Large, fewer
b. Large, more
c. Small, more
d. None of the above

Answer 9

b. Large, more

Question 10

In digital imaging, which of the following determines the range of grayscale available for display?
a. Pixel density
b. Matrix size
c. Pixel bit depth
d. Exposure indicator

Answer 10

c. Pixel bit depth

Question 11

During digital image display, the contrast can be lowered (decreased) by increasing ______
a. Pixel density
b. Grayscale
c. Window level
d. Window width

Answer 11

d. Window width

Question 12

The ability of the imaging system to distinguish between small objects that attenuate the x-ray beam similarly defines:
a. Dynamic range
b. Grayscale
c. insufficient detective quantum efficiency
d. Contrast resolution

Answer 12

d. Contrast resolution

Question 13

Increasing the displayed field of view (FOV) for a fixed matrix size will result in:
a. Decreased pixel pitch
b. Increased pixel size
c. Decrease pixel size
d. Increased pixel bit depth

Answer 13

b. Increased pixel size

Question 14

The visibility of anatomic structures is increased with:
a. Increased contrast-to-noise ratio (CNR)
b. Increased quantum noise
c. Increased signal-to-noise (SNR)
d. a and c only

Answer 14

d. a and c only

Question 15

An imaging system with a higher detective quantum efficiency (DQE):
a. Is more efficient in converting x-ray exposure to a quality image
b. Produces images with decreased spatial resolution
c. Can display anatomic structures with less distortion
d. Produces images with decreased contrast resolution

Answer 15

a. Is more efficient in converting x-ray exposure to

Question 16

Double exposing an image receptor will likely result in:
a. Pixel pitch
b. Foreshortening
c. Increased quantum noise
d. Image artifact

Answer 16

d. Image artifact

Question 17

FOV/Matrix/pixel calculation

Answer 17

Pixel size (mm) = FOV (cm) / matrix size (mm)

Question 18

the amount of luminance (light emission) of a display monitor

Answer 18

image brightness

Question 19

The dynamic range in digital imaging is _____

Answer 19

linear

Question 20

A _____ ______ _____ is only useful if the displayed image brightness can be optimized for human perception

Answer 20

wide dynamic range

Question 21

The ability of the system to distinguish between small objects that attenuate the x-ray beam similarly

Answer 21

Contrast Resolution

Question 22

a control that adjusts the contrast

Answer 22

Window width

Question 23

the image has lower contrast, or more shades of gray

Answer 23

Wide window width

Question 24

the image has higher contrast, or fewer shades of gray

Answer 24

Narrow window width

Question 25

sets the midpoint of the range of brightness levels visible in the image, changing the this on the monitor allows the image brightness to be increased or decreased throughout the entire range of brightness levels

Answer 25

Window level

Question 26

When an image is underexposed excessive _______ ______ may be visible

Answer 26

quantum noise

Question 27

differential absorption, difference in brightness levels

Answer 27

Contrast

Question 28

the combined result of multiple factors associated with the anatomic structure, quality of the radiation, capabilities of the image receptor

Answer 28

Radiographic contrast

Question 29

refers to the absorption characteristics of the anatomic tissue radiographed and the quality of the x-ray beam

Answer 29

Subject contrast

Question 30

What makes a good radiograph?

Answer 30

Accurately represents the anatomic area of interest. The characteristics evaluated for image quality are density or brightness, contrast, recorded detail or spatial resolution, distortion, and noise

Question 31

The brightness of the image can be adjusted using the window level on the monitor to make the image looks better

Answer 31

Monitor brightness

Question 32

Provides a numeric value indicating the level of radiation exposure to the digital image receptor

Answer 32

Exposure indicator

Question 33

Distance measured from the center of a pixel to an adjacent pixel

Answer 33

Pixel pitch

Question 34

Number of pixels per unit area

Answer 34

Pixel density

Question 35

Measure of the imaging system's ability to display the contrast of anatomic objects varying in size, measured 0 and 1.0

Answer 35

Modulation Transfer Function

Question 36

in Modulation Transfer Function 0 =

Answer 36

no difference in brightness level

Question 37

in Modulation Transfer Function 1.0 =

Answer 37

maximum difference in brightness levels

Question 38

Modulation Transfer Function equation

Answer 38

MTF = (maximum intensity - minimum intensity) / (maximum intensity + minimum intensity)

Question 39

Adds unwanted exposure to the radiographic image as a result of compton interactions Decreases contrast

Answer 39

Scatter

Question 40

- A concern in digital imaging, photon-dependent, is visible as brightness fluctuations on the image - The fewer the photons reaching the IR to form the image, the more this will be visible on the digital image - Fix this by increases mAs

Answer 40

Quantum noise

Question 41

- A method of describing the strength of the radiation exposure on the comparison to the amount of noise apparent in the digital image - Increasing this means that the strength of the signal is high compared to the amount of noise - Increasing this will improve the quality of the digital image

Answer 41

Signal-to-Noise Ratio (SNR)

Question 42

- Any unwanted brightness level on a radiographic image - Can result from doubling exposing and IR, improper use of equipment, or patient clothing

Answer 42

Artifacts

Question 43

results from the radiographic misrepresentation of either the size (magnification) or the shape of the anatomic part

Answer 43

Distortion

Question 44

term used to evaluate accuracy of the anatomic structural lines - A radiographic image cannot be an exact reconstruction of the anatomic structure - Diagnostic quality is achieved by maximizing resolution and minimizing image distortion

Answer 44

Spatial resolution

Question 45

A measurement of the efficiency of an image receptor in converting the x-ray exposure it receives to a quality radiographic image

Answer 45

Detective Quantum Efficiency (DQE)

Question 46

The higher the DQE of a system, the _____ the radiation exposure to produce a quality image, thereby _________ patient exposure

Answer 46

lower, decreasing

Question 47

refers to an increase in the image size compared with the object's actual size

Answer 47

Size distortion

Question 48

Shape distortion can appear in two different ways radiographically:

Answer 48

elongation & foreshortening

Question 49

images of objects that appear longer than the true objects

Answer 49

elongation

Question 50

images that appear shorter than the true objects

Answer 50

foreshortening

Question 51

high-contrast =

Answer 51

short scale, fewer gray tones

Question 52

low-contrast =

Answer 52

long scale, many gray tones

Question 53

An imaging system that can resolve a greater number of line pairs per mm (higher spatial frequency) has increased ______ _______

Answer 53

spatial resolution

Question 54

A pixel pair can be equivalent to a ____ ____

Answer 54

line pair

Question 55

Coherent scatter =

Answer 55

radiationless scatter

Question 56

_______ ________ is expressed in line pairs per mm of pixel size

Answer 56

Spatial frequency