Deck 4: Effective Use of Computed Radiography

Question 1

What results in flattening of the luminance from the plate and loss of contrast?

A) scatter radiation
B) incorrect beam
C) grid cutoff
D) rescaling error

Answer 1

grid cutoff

Question 2

The exposure latitude of a digital detector is substantially lower than screen-film.

Answer 2

False

Question 3

What does it mean when the photon intensity reaching the receptor is lower than that required to produce an optimal image?

A) dynamic range
B) overexposure
C) underexposure
D) speed class

Answer 3

underexposure

Question 4

What is likely to occur if there is substantial extraneous exposure on the plate?

A) dynamic range error
B) image plate response error
C) exposure error
D) histogram analysis error

Question 5

The CR cassettes, or imaging plates (IP), are employed in the same manner as screen/film cassettes in existing radiographic units designed to accommodate software.

Question 6

Which exposure causes the system to rescale the image as if the plate is actually underexposed?

A) high-intensity
B) off-focus
C) speed class
D) low-intensity

Question 7

When performing a mobile chest scan, how is the cassette normally oriented?

A) lengthwise
B) crosswise
C) non grid
D) off-level

Question 8

Overexposure implies dark images and underexposure implies light images.

Question 9

If the image is overexposed by more than 2X to 3X, a portion of the image may be saturated.

Question 10

The optimal alignment for all digital detectors is to have the part and beam centered to the receptor, with four collimation margins perpendicular to the cassette edges.

Question 11

Many of the factors that cause low contrast in film-screen systems also cause low contrast in CR images.

Question 12

With digital systems, what determines the speed class at which the system is operated?

A) overexposure
B) receptor speed
C) receptor exposure
D) resultant image

Question 13

The accuracy of the exposure indicators depends on accurate reader calibration and appropriate exposure field recognition.

Question 14

If the receptor is overexposed by a factor of ____, one would assume that the patient received an equally high exposure.

A) 2X
B) 3X
C) 4X
D) 5X

Question 15

Saturation and ALARA violations are the primary reasons to use appropriate exposure level.

Question 16

The problem with the high frequency grids is that as the frequency increases, the lead content ____.

A) increases
B) decreases
C) stays the same
D) is completely removed

Question 17

Because automatic rescaling produces images with similar brightness, it is viewed as the ____ of the system.

A) exposure latitude
B) speed class
C) dynamic range
D) lateral rib margins

Question 18

Since the grid strips are oriented in the direction of grid tilt, grid cutoff is more likely to occur.

Question 19

Digital image acquisition decouples the relationships between exposure and image appearance via automatic rescaling and image processing algorithms.

Question 20

With digital imaging, automatic rescaling of the image provides images that have similar brightness (density)over an exposure range greater than ____X.

A) 20
B) 30
C) 40
D) 50

Question 21

If a vendor provides a fixed-speed class operation, the system operates as a screen/film system of the selected ____________________.

Question 22

In order to visualize the____________________ structures of interest, some initial preprocessing must occur during imaging data extraction.

Question 23

What limits the irradiated volume and reduces undercutting?

A) scatter
B) saturation
C) collimation
D) overexposure

Question 24

The lack of ____________________ generates more scatter that reduces the contrast.

Question 25

Since the image contrast is generally determined more by the processing algorithm, the ____________________ does not have the impact on final image contrast as with screen/film systems.

Question 26

Except for special extremity plates from ____, all plates are basically made from the same barium fluorohalides and are coated to the same thickness.

A) Agfa
B) Fuji
C) Kodak
D) Konica

Question 27

Which of the following has more of an effect on image contrast than the kVp?

A) grid image
B) differential attenuation
C) processing algorithm
D) scatter fogging

Question 28

Because of the increased sensitivity to scattered radiation, the kVp should not exceed ____ for any nongrid radiography, including chest.

A) 20
B) 40
C) 60
D) 80

Question 29

If the exposure is >100% above the optimal signal level, the ALARA principle is violated, and the extra scatter generated will degrade the ____________________.

Question 30

____ occurs when a large number of the pixels will be at the maximum digital value (black)so that there is no signal difference in the very high exposure areas, resulting in a loss of anatomical structures in that region.

A) Collimation
B) Saturation
C) Substantial overexposure
D) Fogging effect

Question 31

Which of the following is expressed as pixels/mm, also referred to as pixel density?

A) speed screen
B) digital detector
C) spatial resolution
D) sampling frequency

Question 32

Acquiring one image on the smallest plate available avoids which recognition error?

A) exposure field
B) bilateral
C) multiple exposure
D) intrafield scatter

Question 33

____ are much more susceptible to fogging than are conventional film-screen systems.

A) PSP plates
B) image plates
C) IP plates
D) plate margins

Question 34

With CR, grid cutoff does not result in a light image, due to the automatic ____________________ of the image.

Question 35

Because of the wide dynamic range of the PSP plate and automatic rescaling, the relationship between exposure and image brightness is ____________________.

Question 36

Currently, each major vendor uses a unique ____________________ indicator whose values indicate the exposure delivered to the plate.

Question 37

If the exposure field is not recognized, the off-focus radiation and scatter outside the exposure field become part of the ____________________.

Question 38

What is the standard expression for the receptor's contribution to recorded detail?

A) sampling frequency
B) image acquisition
C) saturation
D) spatial resolution

Question 39

_____________________ means that the photon intensity reaching the receptor is higher than that required to produce an optimal image.

Question 40

What would substantial (>2x)overexposure of a body part generate in proportion to the overexposure?

A) high kVp
B) fogging effect
C) low contrast
D) additional scatter

Question 41

____________________ exposures are dramatically affected by the additional scatter, which may not even be removable by a grid.

Question 42

The optimal alignment is field-centered to the ____________________ with four collimation margins parallel to the cassette edges.

Question 43

If there is any question about how long it has been since the plate has been though the read/erase cycle, one should erase the plate, especially if ____________________ images are being performed.

Question 44

By reducing the acquired data width, more of the ____________________ may be visualized for a single image display setting.

Question 45

With cassette-based PSP systems (CR), ____________________ resolution becomes a bit more complicated.

Question 46

With screen/film imaging, the ____________________ of the effect of technical factors is normally based on the image appearance rather that on the physics behind the appearance.

Question 47

If larger body structures are done 3 on 1, the ____________________ scatter will reduce the contrast unless the unexposed areas are shielded between exposures.

Question 48

The factors determining ____________________ included motion factors, geometric factors, and the spatial resolution of the receptor unit (line pair/mm).

Question 49

Because of the light spread between the plate and the light guide, the spatial resolution is less than the ____________________ frequency.

Question 50

Because of their wide dynamic range, PSP plates are much more susceptible to ____________________ than are conventional film-screen systems.