Ch. 28 Recorded Detail (Exp I & II)

Question 1

Recorded detail is…

Answer 1

• The degree of geometric sharpness
• Definition
• The accuracy of the structural lines actually recorded in the radiographic image

Question 2

The unit of resolution in film/screen imaging is…

Answer 2

Line pairs per mm

Question 3

Poor resolution is caused by unacceptable levels of…

Answer 3

Penumbra

Question 4

Which can negatively impact recorded detail?

a. Using small focal spot
b. Good film-screen contact
c. Involuntary motion
d. Minimal OID

Answer 4

c. Involuntary motion

Question 5

Factors affecting recorded detail include…

Answer 5

Focal spot size

Question 6

Resolution is improved when…

Answer 6

SID increases and OID decreases

Question 7

Spatial resolution in digital imaging is determined by the…

Answer 7

• Bit depth
• Matrix size
• Pixel size

Question 8

Which radiograph exhibits the bet detail?

a. PA chest for evaluation of heart at 40”
b. PA chest for evaluation of heart at 72”
c. AP chest for evaluation of heart at 40”
d. AP chest for evaluation of heart at 72”

Answer 8

b. PA chest for evaluation of heart at 72”

Question 9

As focal spot size decreases…

Answer 9

• Umbra is improved
• Penumbra decreases
• Resolution increases

Question 10

Penumbra decreases as…

Answer 10

• Focal spot decreases
• OID decreases
• SID increases

Question 11

Slow film-screen combinations…

Answer 11

Increase resolution

Question 12

Resolution with intensifying screens will increase as ____ increases.

Answer 12

Phosphor concentration

Question 13

The best method for controlling motion when the patient is unable to cooperate is to…

Answer 13

Maintain mAs, while decreasing time.

Question 14

As a last resort, which human immobilizer is used to hold a patient in position?

Answer 14

The male relative

Question 15

The ____ represents a depth to the information in the digital image.

Answer 15

z axis

Question 16

Which measures the accuracy of an image compared to the original object on a scale of 0 to 1?

Answer 16

Modulation Transfer Function (MTF)

Question 17

All of the following increase visibility of detail EXCEPT:

a. 15% rule
b. filtration
c. Radiographic grids
d. SID

Answer 17

d. SID

Question 18

When evaluating the degree of resolution on an actual radiographic image, an effective tissue to analyze is…

Answer 18

Bony trabecular pattern

Question 19

A pixel bit depth of 2^16 will demonstrate ____ shades of gray.

Answer 19

65,536

Question 20

As the spatial frequency of objects increases,

Answer 20

MTF decreases

Question 21

For general radiography, an MTF value of 1 is…

Answer 21

Theoretically impossible

Question 22

Imaging noise is different from quantum noise in that imaging noise…

Answer 22

Is inherent in the imaging system

Question 23

In general radiography, quantum noise is…

Answer 23

A function of mAs and kVp.

Question 24

The Nyquist frequency is…

Answer 24

Sampling a minimum of twice per cycle

Question 25

In digital imaging systems, increasing sampling frequency of the data…

Answer 25

Increases image fidelity

Question 26

When the sampling frequency is less than the Nyquist value,

Answer 26

The Moire effect can occur

Question 27

The overall general shape of a human anatomical structure is…

Answer 27

Round or oval

Question 28

A digital detector with a high fill factor…

Answer 28

Will produce high resolution

Question 29

You have completed a chest radiograph on a 2 month old infant using a restraining device at 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. In an effort to improve the quality of the repeat image, the competent radiographer would…

Answer 29

Raise mA and decrease the exposure time.