Chapter 28 (Module 1)

Question 1

Spatial resolution is
a. the degree of geometric sharpness.
b. definition.
c. the accuracy of the structural lines actually recorded in the radiographic image.
d. all of the above.

Answer 1

All of the above

Question 2

The traditional unit of resolution measurement typically used in film/screen imaging is
a. dots per millimeter.
b. line pairs per millimeter.
c. pixel size.
d. the DEL size.

Answer 2

line pairs per millimeter

Question 3

Poor spatial resolution is caused by unacceptable levels of
a. IR exposure.
b. umbra.
c. penumbra.
d. contrast.

Answer 3

Penumbra

Question 4

Which can negatively impact recorded detail?
a. using small focal spot
b. longer SID
c. involuntary motion
d. minimal OID

Answer 4

involuntary motion

Question 5

Factors affecting recorded detail include
a. kVp and filtration.
b. radiographic grids and collimation.
c. mAs and grid ratio.
d. focal spot size and patient thickness.

Answer 5

focal spot size and patient thickness

Question 6

Spatial resolution is improved when
a. OID increases.
b. OID decreases.
c. SID decreases.
d. the x-ray tube is angled.

Answer 6

OID decreases

Question 7

Spatial resolution is improved when
a. OID increases.
b. SID increases.
c. SID decreases.
d. the receptor is angled.

Answer 7

SID increases

Question 8

Spatial resolution in digital imaging is determined by the
a. bit depth.
b. matrix size.
c. pixel size.
d. all of the above.

Answer 8

all of the above

Question 9

Which radiograph below exhibits the best recorded detail?
a. a PA chest radiograph for evaluation of the heart at 40 in.
b. a PA chest radiograph for evaluation of the heart at 72 in.
c. a lordotic projection of the chest at 72”.
d. an AP chest radiograph for evaluation of the heart at 72 in.

Answer 9

a PA chest radiograph for evaluation of the heart at 72 inches

Question 10

As focal spot size decreases,
a. umbra is improved.
b. penumbra decreases.
c. spatial resolution increases.
d. all of the above.

Answer 10

all of the above

Question 11

Penumbra decreases as
a. focal spot decreases.
b. OID decreases.
c. SID increases.
d. all of the above.

Answer 11

all of the above

Question 12

When switching from a 400 RS film screen combination to a 200 RS system, one should expect
a. an increase in spatial resolution.
b. to use a longer exposure time.
c. a decrease in patient dose.
d. a decrease in spatial resolution.

Answer 12

an increase in spatial resolution

Question 13

In order to improve the temporal resolution on an image,
a. a longer SID should be used
b. a smaller x-ray beam angle should be used
c. a shorter exposure time should be used
d. the 15% rule should be considered

Answer 13

a shorter exposure time should be used

Question 14

The best method for controlling motion when the patient is unable to cooperate is to
a. decrease the focal spot size.
b. maintain mAs, while decreasing time.
c. maintain mAs, while decreasing mA.
d. decrease kVp.

Answer 14

maintain mAs, while decreasing time

Question 15

As a last resort, which human immobilizer is used to hold a patient in position?
a. the radiography student
b. the radiologic technologist
c. the ER nurse
d. the male relative

Answer 15

the male relative

Question 16

The ____ represents a depth to the information in the digital image.
a. z axis
b. y-x grid matrix
c. y axis
d. x-y grid matrix

Answer 16

z axis

Question 17

The composite measure of image accuracy compared to the original object, on a scale of 0 to 1 is referred to as?
a. line spread function
b. modulation transfer function
c. point spread function
d. noise reduction function

Answer 17

modulation transfer function

Question 18

All of the following affect visibility of detail EXCEPT
a. 15% rule.
b. filtration.
c. radiographic grids.
d. SID.

Answer 18

SID

Question 19

As object spatial frequencies increase
a. MTF increases
b. MTF decreases
c. Nyquist is not a factor
d. MTF is unaffected

Answer 19

MTF is unaffected

Question 20

A pixel bit depth of 216 will demonstrate _______ shades of gray
a. 32
b. 256
c. 4096
d. none of the above

Answer 20

none of the above

Question 21

As the spatial frequency of objects increases,
a. MTF increases proportionally.
b. MTF decreases.
c. MTF values approach 1.
d. MTF computes to a value of 1.

Answer 21

MTF decreases

Question 22

For general radiography, an MTF value of 1 is
a. average.
b. suboptimum.
c. theoretically impossible.
d. a function of mAs.

Answer 22

theoretically impossible

Question 23

Imaging noise is different from quantum noise in that imaging noise
a. is a function of mAs.
b. is dependent upon kVp.
c. is inherent in the imaging system.
d. cannot be filtered out.

Answer 23

is inherent in the imaging system

Question 24

In general radiography, quantum noise is
a. filtered out of images.
b. a function of mAs and kVp.
c. designed into the receptor specifications.
d. a recorded detail parameter.

Answer 24

a function of mAs and kVp

Question 25

The Nyquist frequency is a. important in analog imaging. b. sampling a minimum of twice per cycle. c. unique to radiography. d. related to involuntary motion.

Answer 25

sampling a minimum of twice per cycle

Question 26

In digital imaging systems, increasing sampling frequency of the data a. increases dose. b. increases image fidelity. c. decreases MTF. d. decreases dose.

Answer 26

increases image fidelity

Question 27

When the sampling frequency is less than the Nyquist value, a. aliasing is eliminated. b. the Moire effect can occur. c. patient dose must increase. d. the Nyquist value must be altered.

Answer 27

the Moire effect can occur

Question 28

The overall general shape of human anatomical structures are a. round or oval. b. linear. c. cuboid. d. curvilinear.

Answer 28

round or oval

Question 29

A digital detector with a high fill factor a. will produce poor resolution. b. will require longer processing time. c. will produce high resolution. d. requires more radiation exposure.

Answer 29

will produce high resolution

Question 30

You have completed a chest radiograph on a 2-month-old infant using a restraining device at a 72” SID. Because of the design of the device, your OID is suboptimum. The image reveals good resolution of the bony anatomy but the pulmonary vasculature is blurred. The EI value is 2040 and the target EI value is 2000. In an effort to improve the quality of the repeat image, the competent radiographer would a. raise the mA and decrease the exposure time. b. decrease the SID and maintain the same mAs. c. switch to small focal spot. d. ask for mild sedation of the infant to decease respiration.

Answer 30

raise the mA and decrease the exposure time

Question 31

On a PA projection of the wrist, you notice what appears to be a soft tissue mass superimposed over the bony anatomy. When you inspect the patient, you notice the presence of a large linear scar from a previous injury. The visualization of this scar is primarily due to what characteristic of digital detectors? a. temporal resolution b. low contrast resolution c. high contrast resolution d. the DEL fill factor

Answer 31

low contrast resolution

Question 32

Quantum noise impacts radiographic image quality by a. decreasing geometric unsharpness. b. increasing temporal resolution. c. diminishing the visibility of recorded detail. d. adding artifacts to the image.

Answer 32

diminishing the visibility of recorded detail

Question 33

From the choices below, select the FALSE statement regarding Contrast-Noise-Ratio(CNR) a. It is the ratio of the signal difference between areas of interest b. It is affected by SNR c. A high CNR is only possible with a low SNR d. If image noise is high, the CNR will be low

Answer 33

A high CNR is only possible with a low SNR

Question 34

A convenient and easy patient immobilization method an experienced radiographer will use is a. a high mA and short exposure time b. a high kVp and low mA c. a piece of tape wrapped around the patient’s anatomy d. a tissue bolus material to hold the body part in position

Answer 34

a piece of tape wrapped around the patient's anatomy

Question 35

Of the choices given below, which one would yield the highest image quality? a. 600 mA, 85 kVp, .70 sec. exp time, 1.2 mm fs, 1.5 mm Al filtration, 4 lp/mm, MTF= 40% b. 300 mA, 97 kVp, .35 sec exp time 1.2 mm fs, 1.5 mm Al filtration, 3 lp/mm, MTF= 25% c. 600 mA, 85 kVp, .70 sec exp time 0.6 mm fs, 1.0 mm Al filtration, 1.5 lp/mm, MTF= 60% d. 200 mA, 110 kVp, .25 sec exp time, 2.0 mm fs 1.2 mm Al filtration 2 lp/mm, MTF = 30%

Answer 35

600 mA, 85 kVp, .70 sec. exp time, 1.2 mm fs, 1.5 mm Al filtration, 4 lp/mm, MTF = 40%