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Oral Radiology > Factors Effecting X-ray Beam Intensity- Lecture 5 > Flashcards

Factors Effecting X-ray Beam Intensity- Lecture 5 Flashcards

1
Q

Total amount of energy contained in the x-ray beam:

A

intensity

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2
Q

Intensity =

A

quantity x quality

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3
Q

The average energy in the x-ray beam:

A

quality

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4
Q

Quality is related to:

A

tube voltage (kVp)

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5
Q

According to quality, the x-ray beam is:

A

heterogeneous

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6
Q

The number of photons in the x-ray beam:

A

quantity

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7
Q

Quantity is related to tube ___ and ___

A

current; exposure time (mAs)

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8
Q

List the factors affecting intensity: (6)

A
  1. Kilovoltage
  2. Milliamperage
  3. Exposure time
  4. Filtration
  5. Collimation
  6. Source to film distance (inverse square law)
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9
Q

The inverse square law describes:

A

source to film distance (factor affecting intensity)

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10
Q

As tube voltage increases:
1. The number of photons generated ____ (_____)
2. Mean energy of photon ____ (_____)
3. Maximum energy of photon ____

A
  1. increases (increased quantity)
  2. increases (increased quality)
  3. increases
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11
Q

As exposure time increases:
1. The number of photons generated ____ (____)
2. The mean energy of photons _____ (_____)
3. Maximum energy of photons _____ (_____)

A
  1. increases (increased quantity)
  2. is unchanged (unchanged quality)
  3. is unchanged (unchanged quality)
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12
Q

As tube current (mA) increases:
1. The number of photons generated ____ (____)
2. The mean energy of photons _____ (_____)
3. The maximum energy of photons____ (_____)

A
  1. increases (increased quantity)
  2. is unchanged (unchanged quality)
  3. is unchanged (unchanged quality)
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13
Q

Selectively removes long wavelength (low energy) x-rays:

A

filtration

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14
Q
  • glass envelope
  • immersion oil
  • metal housing
  • tube window

These are all considered:

A

inherent filtration

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15
Q

The aluminum discs are considered:

A

added filtration

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16
Q

As filtration increases:
1. Number of photons ____ (____)
2. The mean energy of photons ____ (___)
3. Maximum energy of photons _____.

A
  1. decreases (decreased quantity)
  2. increases (increased quality)
  3. is unchanged
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17
Q

Restricts the size and shape of the beam:

A

collimation

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18
Q

With collimation:
1. Number of photons ____
2. mean energy of photons _____
3. maximum energy of photons _____

A
  1. decreases
  2. is unchanged
  3. is unchanged
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19
Q

The intensity of the beam varies inversely to:

A

The square of the source-to-receptor distance

20
Q

A method of calculating the new beam intensity when changing the source-to-receptor distance:

A

Inverse square law

21
Q

According to the inverse square law:

If the distance is doubled (8 to 16) = new intensity will be:

If the distance is tripled (4 to 12) = new intensity will be:

If distance is halved (16 to 8) = new intensity will be:

A

1/4 (inverse of 2^2)

1/9 (inverse of 3^2)

4x (inverse of 1/2^2)

22
Q

As source-to-receptor distance increases:

  1. Number of photons ____. (____)
  2. Mean energy of photons ____. (____)
  3. Maximum energy of photons _____
A
  1. decreases (decreased quantity)
  2. is unchanged (unchanged quality)
  3. is unchanged
23
Q

Increasing the source to film distance by 2 decreases photons by:

A

1/4 (by 4)

24
Q

Which of the 6 factors affect the quantity of the x-ray beam?

  1. Tube voltage (kVp)
  2. Tube current (mA)
  3. Exposure time (s)
  4. mAs
  5. Distance
  6. Filtration
A

All of them affect quantity

25
Q

Which of the 6 factors affect the quality of the x-ray beam?

  1. Tube voltage (kVp)
  2. Tube current (mA)
  3. Exposure time (s)
  4. mAs
  5. Distance
  6. Filtration
A

filtration and tube voltage (kVp)

26
Q

Density is altered by factors affecting the ____ of the beam

A

quantity

27
Q

Contrast is altered by factors affecting the ____ of the beam

A

quality

28
Q

Amount of blackness in an image:

A

density

29
Q

Density is the amount of blackness in an image which is related to:

A

how many x-rays reach the receptor

30
Q

Density is primarily controlled by ____ and less so by ___

A

mAs (mA & exposure time); kVP

31
Q

Increasing the source-to-film distance will decrease ____ due to decreased number of photons

A

density

32
Q

Increasing the source-to-film distance has what affect density? why?

A

decreases density (due to decreased number of photons)

33
Q

mA and exposure time are inversely proportional describing:

A

mAs rule (density)

34
Q

If mA is increased, what must happen to exposure time to maintain the same density of the image?

A

exposure time must be decreased

35
Q

If mA is decreased, what must happen to exposure time to maintain the same density of the image?

A

exposure time must be increased

36
Q

The difference in densities between light and dark regions of a radiograph:

A

contrast

37
Q

Contrast is primarily controlled by the:

A

voltage

38
Q
  • air
  • bone
  • metal
  • tongue
  • enamel

Put in order from lowest to highest contrast (dark to light on radiograph)

A
  1. air (darkest)
  2. tongue
  3. bone
  4. enamel
  5. metal (lightest)
39
Q

The short gray scale is involved in:

A

high contrast

40
Q

The long gray scale is involved in:

A

low contrast

41
Q

High contrast (short gray scale) = ____ kVp

A

low kVp (long wavelengths; less penetrating)

42
Q

In the short gray scale (high contrast), density differences between adjacent areas are ___.

____ shades of gray.

A

greater; fewer

43
Q

Low contrast (long gray scale) = ____ kVp

A

high kVp (short wavelengths; more penetrating)

44
Q

In the long gray scale (low contrast), density differences between adjacent areas are ____.

____ shades of gray

A

more subtle; more

45
Q

Effect of kVp on contrast:

Low kVp = ____ contrast

High kVp = _____ contrast

A

high contrast (short gray scale)

low contrast (long gray scale)

46
Q
A

Oral Radiology (21 decks)

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