Radiographic Image Characteristics

Question 1

Will you always get an image? Why?

Answer 1

• Yes
• Receptors are designed to respond to radiation

Question 2

What is the goal of an image?

Answer 2

Optimum diagnostic quality with minimal patient radiation exposure

Question 3

What is a good radiographic image?

Answer 3

A radiograph that reproduces anatomical structures/tissue

Question 4

Image characteristics

Answer 4

• Density
• Contrast
• Noise

Question 5

This degree and pattern of darkness depends on…

Answer 5

• Energy and intensity of x-ray photons
• Subject composition

Question 6

Characteristic radiation

Answer 6

Interacts primarily valence electrons

Question 7

Breaking radiation

Answer 7

Produces electrons that primarily interact with the nucleus

Question 8

Radiographic density definition

Answer 8

Overall degree of darkening of the image or exposed image receptor

Question 9

Low density

Answer 9

Underexposed, too light

Question 10

High density

Answer 10

Over exposure, too dark

Question 11

Primary controlling factor of density

Answer 11

Milliamperage, mA

Question 12

Contributing factors for density

Answer 12

• Exposure time, seconds
• Distance

Question 13

Will density be equal if mA is equal when comparing?

Answer 13

Yes

Question 14

Do you change kVp to change density?

Answer 14

No

Question 15

mAs directly control…

Answer 15

The number of x-ray photons produced

Question 16

If mAs increase, then density…

Answer 16

Increases

Question 17

What is the ideal exposure time when mA is constant?

Answer 17

0.5 seconds

Question 18

Effects of distance in radiographs include…

Answer 18

• Intensity of x-ray beam reduces as focal spot to object distance increases
• Inverse square law

Question 19

Primary factor in density?

Answer 19

mA

Question 20

kVp is the primary factor for…

Answer 20

Contrast

Question 21

As you increase the kVp, do you increase or decrease penetrability of the x-ray?

Answer 21

Increase

Question 22

As thickness increases, the more photons…

Answer 22

Absorbed

Question 23

As thickness decreases, the more photons

Answer 23

Hit the sensor

Question 24

Is enamel high or low in atomic number?

Answer 24

High

Question 25

Is enamel radiolucent or radiopaque?

Answer 25

Radiopaque

Question 26

Attenuated definition

Answer 26

Absorbed

Question 27

The thicker the subject or object is, the more the beam is attenuated, and...

Answer 27

The light becomes the resultant image

Question 28

Range of kVp in dental clinics are...

Answer 28

60-70 kVp

Question 29

In order to achieve optimum density, kVp or time should be adjusted when...

Answer 29

Subject thickness varies

Question 30

Image contrast is...

Answer 30

The degree of difference in the shades of the gray on the radiograph

Question 31

High contrast

Answer 31

- Few shades of gray - Low kVp - Short scale contrast

Question 32

Low contrast

Answer 32

- Many shades of gray - High kVp - Long scale of gray, more colors

Question 33

Children require more or less radiation compared to adults?

Answer 33

Less

Question 34

Noise

Answer 34

- Spurious information about an object - Degrades images - Makes difficult to differentiate between structure

Question 35

Noise is the appearance of uneven _______ in a digital sensor

Answer 35

Density

Question 36

As mA increase, density

Answer 36

Increases

Question 37

As mA decreases, density

Answer 37

Decreases

Question 38

As kV increases, density

Answer 38

Increases

Question 39

As kV decreases, density

Answer 39

Decreases

Question 40

As time increases, density

Answer 40

Increases

Question 41

As time decreases, density

Answer 41

Decreases

Question 42

As thickness increases, density

Answer 42

Decreases

Question 43

Increased kV leads to ___ - scale contrast

Answer 43

Low -scale contrast, low contrast

Question 44

Decreased kV leads to ___ - scale contrast

Answer 44

Short-scale contrast, high contrast

Question 45

Image sharpness

Answer 45

Measurement of how well a boundary between two areas of differing radiodensity is revealed

Question 46

Spatial resolution

Answer 46

Measures how well a radiograph is able to reveal small objects that are close

Question 47

Smaller the focal spot..

Answer 47

The sharper the image

Question 48

Can you control the focal spot size?

Answer 48

No

Question 49

If you move sensor away from tooth, the image will...

Answer 49

Not be sharp

Question 50

If you increase distance from focal spot, you will avoid...

Answer 50

Magnification error, including foreshortening and elongating

Question 51

Radiographic sharpness

Answer 51

Ability of radiographic to define an edge precisely

Question 52

Radiographic resolution

Answer 52

Ability of the radiograph to record separate structures that are close together

Question 53

An increase in the mA, kVp, or exposure time will increase...

Answer 53

The overall density of the image

Question 54

mAs directly control what?

Answer 54

Number of x-ray photons produced

Question 55

What does kVp control?

Answer 55

Energy and penetrability/quality of x-ray

Question 56

High kVp is specifically used in what kind of objects?

Answer 56

Thick objects

Question 57

As subject/object thickness increases, what happens to X-ray absorption and density?

Answer 57

Absorption increases, density decreases

Question 58

What is image contrast?

Answer 58

Degree of difference in the shades of gray on the radiograph

Question 59

Why is contrast important?

Answer 59

Various structures and pathologies will pop up if contrast is good

Question 60

What are other factors that contribute to image contrast?

Answer 60

Subject thickness, density, and atomic number

Question 61

Does an increasing kVp increase or decrease the subject contrast?

Answer 61

Decreases