8/27: Factors Controlling X-Ray Beam Intensity Flashcards
(57 cards)
1
Q
- The total amount of energy contained in the x-ray beam
A
Intensity
2
Q
- Intensity =
A
a. Quantity x Quality
3
Q
- The number of photons in the beam
A
a. Quantity
4
Q
- “Quantity” is primarily related to ____ and ____ and less so by tube voltage (kVp)
A
a. Tube current
b. Exposure time
5
Q
- This is the average energy in the x-ray beam
A
a. quality
6
Q
- Quantity is expressed as
A
a. Current (mA) x Time (sec) → mAs
7
Q
- This is controlled primarily by the tube voltage (kVp)
A
a. Quality
8
Q
- X-ray of the beam is
A
a. Heterogenous
9
Q
- What are the 6 factors that control the x-ray beam intensity?
A
a. Tube voltage
b. Exposure time
c. Tube current
d. Filtration
e. Collimation
f. Source-receptor distance
10
Q
- As the tube voltage increases, what happens to the number of photons generated?
A
a. Increases (quantity)
11
Q
- As the tube voltage increases, what happens to the mean energy of photons?
A
a. Increases (quality)
12
Q
- As the tube voltage increases, what happens to the maximum energy of photons?
A
a. increases
13
Q
- As the tube voltage increases, what 3 things occur?
A
a. Increase # of photons
b. Increase mean energy of photons
c. Increases maximum energy of photons
14
Q
- As exposure time increases, what happens to the number of photons generated?
A
a. Increase (quantity)
15
Q
- As exposure time increases, what happens to the mean energy of photons?
A
a. Quality unchanged
16
Q
- As exposure time increases, what happens to the maximum energy of photons?
A
a. Quality unchanged
17
Q
- The tube current is represented as
A
mA
18
Q
- As mA increases, what happens to the number of photons?
A
a. Increases (increased quantity)
19
Q
- As mA increases, what happens to the mean energy of photons?
A
a. Remains unchanged
20
Q
- As mA increases, what happens to the maximum energy of photons?
A
a. Remain unchanged
21
Q
- This selectively removes long wavelength (low energy) x-rays
A
a. Filtration
22
Q
- Kind of x-rays does filtration remove?
A
a. Long wavelength (low energy)
23
Q
- Total filtration =
A
a. Inherent filtration + added filtration
24
Q
- What factor that affects x-ray intensity decreases the quantity of photons?
A
a. filtration
25
25. What are examples of inherent filtration?
a. Glass envelope
b. Immersion oil
c. Metal housing
d. Tube window
26
26. What are examples of added filtration?
a. Aluminum disk
27
27. As filtration increases, what happens to the number of photons?
a. Decreases (decrease quantity)
28
28. As filtration increases, what happens to the mean energy of photons?
a. Increases (increases quality)
29
29. As filtration increases, what happens to the maximum energy of photons?
a. Remains unchanged
30
30. This restricts the size and shape of the beam
a. Collimation
31
31. What 3 things happen with collimation?
a. # of photons decreases
b. Mean energy of photons is unchanged
c. Maximum energy of photons is unchanged
32
32. The intensity of the beam varies to what law?
a. Inverse square law
33
33. The intensity of the beam varies inversely to the square of the
a. Source-to-receptor distance
34
34. If the distance is doubled (8-16), the new intensity will be
a. 1⁄4
35
35. If the distance is tripled (4-12), the new intensity will be
a. 1/9
36
36. If the distance is halved (16-8), the new intensity will be
a. 4x
37
37. As source-to-receptor increases, what 3 things happen?
a. # of photons decreases (decreased quantity)
b. Mean energy of photons is unchanged
c. Maximum energy of photons is unchanged
38
38. This is altered by factors affecting Quantity of the beam
a. Density
39
40. The amount of blackness of an energy is related to what?
a. How many x-rays reach the receptor
40
39. This is altered by factors affecting the Quality of the beam
a. Contrast
41
41. Density is primarily controlled by mA or kVp?
a. mA
42
42. Decreasing mA does what to density?
a. decreases
43
43. Increasing the quantity will increase what?
a. Density of an image (making it darker)
44
44. if you increase density, what happens to the radiograph image?
a. Becomes darker
45
45. If you decrease density, what happens to the radiograph image?
a. Becomes lighter
46
46. Density controls what?
a. blackness
47
47. What is the mA rule of density?
a. mA and exposure time are inversely proportional
48
48. Are mA and exposure time directly or inversely proportional?
a. Inversely
49
49. This is the difference in densities between light and dark regions of a radiograph
a. Contrast
50
50. Lower contrast means what?
a. More shades of gray
51
51. Higher contrasts means what?
a. Less shades of gray
52
52. Contrast is primarily controlled by what?
a. Voltage (kVp)
53
53. What affects contrast?
kV
54
54. Does high contrast have low or high kVp?
a. Low kVp
55
55. Does low contrast have low or high kVp?
a. High kVp
55
56. High contrasts produce what?
a. Short gray scale, low kV
56
57. Low contrast produces what?
a. Long gray scale, high kV
