Radiography: Image Acquisition and Evaluation

Question 1

What radiography imaging system feature measures and automatically terminates exposure when a preset amount of radiation is detected?

Answer 1

Automatic exposure control

Question 2

Would imaging a patient with a small bowel obstruction require an increase or decrease in radiographic technique to maintain receptor exposure?

Answer 2

A decrease

Question 3

Would imaging a patient with ascites require an increase or decrease in exposure factors?

Answer 3

An increase

Question 4

Misrepresentation of the true size or shape of an imaged part is known as ___________________

Answer 4

distortion

Question 5

Loss of detail in a radiographic image will occur if the object-to-image distance is increased or decreased?

Answer 5

Increased

Question 6

Will elongation or foreshortening occur if there’s an increase in X-ray tube angulation?

Answer 6

Elongation

Question 7

If an insufficient number of X-ray photons reach the detector, what will the resulting image demonstrate?

Answer 7

Quantum noise (or quantum mottle)

Question 8

Standard radiographic X-ray tubes typically have focal spot sizes in what size ranges, from small focus to large focus?

Answer 8

0.6 mm for small focus to 1.2 mm for large focus

Question 9

What are the 3 factors that keep a radiographic image from losing detail and becoming unsharp?

Answer 9

**Source size/Source-to-image-receptor distance (SID), source-to-object distance (SOD), and object-to-image-receptor distance (OID) **

Question 10

A grid ratio is defined as the relationship between the height of the lead strips and the _________________ .

Answer 10

distance between the lead strips

Question 11

Which grid has lead strips angled to coincide with the divergence of the X-ray beam?

Answer 11

A focused grid

Question 12

The number of grid lines per inch or centimeter is called the __________________ .

Answer 12

**grid frequency **

Question 13

The absorption of the useful beam with resulting loss of exposure across the image receptor is called _______________________

Answer 13

grid cutoff

Question 14

Which grid ration will absorb the most scatter radiation: 8:1, 10:1, 12:1, or 16:1?

Answer 14

**16:1 **

Question 15

What range of grid ratios is most often used for general-purpose X-ray imaging systems?

Answer 15

Between 10:1 and 12:1

Question 16

Grids should be used when the thickness of the anatomy being radiographed exceeds ________________.

Answer 16

Approximately 3.93 inches (10 cm)

Question 17

What technical factor must be increased when using a grid to compensate for absorbed X-ray photons?

Answer 17

mAs

Question 18

When mAs adjustments are not possible, image receptor exposure can be doubled or halved by employing what rule?

Answer 18

The 15% Rule

Question 19

_______________________ technique charts provide the lowest amount of patient radiation exposure.

Answer 19

Variable kV (or kVp)

Question 20

What specific technique setting must be adjusted when imaging a patient undergoing a barium enema?

Answer 20

kVp

Question 21

What type of technique chart uses a fixed mA value and a kVp that varies according to the thickness of the anatomy being imaged?

Answer 21

A variable-kVp radiographic technique chart

Question 22

Is the resulting image contrast higher or lower when using a variable kVp technique chart versus using a fixed kVp technique chart?

Answer 22

**Higher **

Question 23

In digital radiography, _________________ and ___________________are determined by computer software and monitor controls.

Answer 23

brightness and contrast

Question 24

In digital radiography, the _________________________ provides critical exposure feedback that the correct imaging settings have been received by the phosphors in the imaging plate, which are usually proprietary.

Answer 24

exposure indicator/index (EI) or deviation indicator/index (DI)

Question 25

The ability to distinctly image small objects next to each other, with high contrast, is referred to as ________________.

Answer 25

spatial resolution

Question 26

_____________________ is the ratio of an image to the object as a function of spatial frequency.

Answer 26

The modulation transfer function

Question 27

___________________ is the measurement of how efficiently a detector converts incident X-ray photons into useful image signals (relative to noise).

Answer 27

Detective quantum efficiency

Question 28

Scatter radiation produced by extra tissue in the X-ray field from improper collimation or lack of shielding, that degrades image quality, results in what effect?

Answer 28

**The “fogging” effect **

Question 29

In digital radiography, _____________________ is the range of X-ray intensities, or shades of gray, that a digital system can reproduce.

Answer 29

the dynamic range

Question 30

______________________ is an interference pattern/artifact caused by the coincidence of grid lines and a scanning laser in a computed radiography system.

Answer 30

A moiré pattern

Question 31

The inadvertent use of more radiation dose to overcome the noise effect of underexposure is commonly known as ________________.

Answer 31

**dose creep **

Question 32

In a standard radiographic table, how many sensors (cells) are typically contained within an automatic exposure control device?

Answer 32

3

Question 33

In radiography, ____________________ is proportional to the amount of image contrast and the square root of the number of photons that are transmitted.

Answer 33

the signal-to-noise ratio

Question 34

The range of exposure value to the receptor that produce an optimal diagnostic image is known as _______________ .

Answer 34

**exposure latitude **

Question 35

In computed radiography, this is comprised of europium-doped barium fluorohalide.

Answer 35

A photostimulable phosphor plate

Question 36

The spatial resolution in a flat-panel digital radiography receptor is primarily controlled by the size of the ___________________ .

Answer 36

detector elements

Question 37

If an image is produced with a low number of X-rays, will the quantum mottle be higher or lower than if the image was formed with a high number of X-rays?

Answer 37

Higher

Question 38

TRUE or FALSE: Information about exposure techniques involving adding X-ray beam filtration is NOT needed on a radiographic exposure technique chart.

Answer 38

True

Question 39

Radiographic contrast is the product of which 2 factors?

Answer 39

Image receptor contrast and subject contrast

Question 40

What law states that regardless of whether a radiograph is made with short exposure time or long exposure time, the receptor exposure will be the same if the mA value is constant?

Answer 40

The reciprocity law