MIDSEM TQ Flashcards
1
Q
- how many protons (atomic #) does Tungsten (W) have?
A
- protons: 74 (high atomic # is more efficient in x-ray production)
2
Q
- true or false: electrons come out of the xray machine
A
- false: photons come out of the xray machine
3
Q
- each photon carries so little energy, what can you only experience?
A
- “collective effect” of many photons
4
Q
- 10^-3 & 10^3 are scientifically abbreviated how?
A
- 10^-3 = kilo- & 10^3 = milli-
5
Q
- what results from total penetration?
A
- no image - body has to absorb or scatter it
6
Q
- what do x-rays react with on the film?
A
- silver halide
7
Q
- what does alternating current need to be converted to for usage?
A
- direct current
8
Q
- how is low-voltage AC current converted to high-voltage AC current
A
- transformed - kicked up
9
Q
- ripple factors: half-wave, unfiltered & filtered
A
- unfiltered: 100% filtered: 20% (better, smoothed out)
10
Q
- ripple factors: full-wave, unfiltered & filtered
A
- unfiltered: 100% filtered: 9% (good, very smooth)
11
Q
- negatively charged tungsten cathode
A
- coiled filament(s)
12
Q
- positively charged copper anode
A
- embedded tungsten target
13
Q
- ____ functions to produce electrons
A
- cathode (anode receives because it is oppositely charged)
14
Q
- heat-induced flow of charge carriers from a surface or over a potential-energy barrier
A
- thermoionic emission
15
Q
- what does milliampers (ma) control directly?
A
- directly = tube current = xray beam
16
Q
- what does kVp control directly?
A
- directly = filament heat = tube current = xray beam
17
Q
- what does total filtration =
A
- added + inherent
18
Q
- what does ‘beam hardening’ do?
A
- filter out low protons beams
19
Q
- compensating filter: used for the foot
A
- wedge filter
20
Q
- compensating filter: used for chest
A
- trough / bilateral wedge filter
21
Q
- what is the break down of the 1% of anode interactions (useful x-rays)?
A
- bremsstrahlung (0.9%) & characteristic (0.1%)
22
Q
- what is directly proportional to beam intensity?
A
- mAs and beam intensity are directly proportional
23
Q
- what affects film blackening?
A
- kilovoltage (kVp)
24
Q
- how do you maintain a constant film density?
A
- increase kVp by 15% (should be accompanied by 50% decrease of the mAs)
25
25. what does film density = ?
25. film density = film blackness (air = black)
26
26. what happens if you increase atomic #?
26. increase quantity and quality
27
27. 2 basic factors affecting quality of x-ray beam photons?
27. 1.kilovoltage (kVp) 2.filtration
28
28. what are 3 ways energy (radiation) is transferred to any material which it interacts?
28. 1.penetrates 2.absorbed 3.scattered
29
29. 4 factors affecting attenuation?
29. 1.kilovoltage (faster cars) 2.density 3.atomic number (Z) 4.electrons per gram of tissue
30
30. measures the amount of radiation energy (E) absorbed per unit mass (M) of the absorbing medium
30. absorbed dose (D) = (E) / (M)
31
31. 1 Gy = ____
31. 1 Gy = 100 rads
32
32. 1 rad = ____
32. 1 rad = 10 mGy
33
33. 1 Sv = ____
33. 1 Sv = 100 rem (1 rem = 10 mSv)
34
34. what is silver (Ag+1) reduced to?
34. ionic (Ag+1) is reduced to metallic (Ag 0) ....(that's a zero. loss of electron) ****over time all undeveloped silver halide is reduced to silver
35
35. converts silver halide crystals with latent image centers into ________
35. flecks of silver
36
36. activators: ______ provides acid media (pH 4.0) for hardener & also helps neutralize developer
36. acetic acid
37
37. film types: are non-screen films enhanced x-ray sensitivity or enhanced light sensitivity?
37. enhanced x-ray sensitivity
38
38. how does a fluoroscope work?
38. produces a real-time image (know that it is an inverted ( - ) image. areas that look dark are light)
39
39. what kind of light does silver halide respond to?
39. violet & blue (not green, yellow or red)
40
40. digital radiography replaces film with reusable detector. what are they 2 types of systems?
40. 1.cassette-based 2.cassette-less
41
41. what 3 things does scattered radiation increase with?
41. 1.increasing part thickness 2.increased field size 3.increased energy (kVp) of x-rays
42
42. at a transmittance (T%) of 50% what is the optical film density?
42. 0.3
43
43. if you increase kilovoltage how does that affect contrast?
43. increases contrast
44
44. does changing miliamps affect contrast?
44. no (*note: mA x time (mAs) does not affect subject contrast either
45
45. any degree of darkening on the film that occurs outside exposure process is ____?
45. fog
46
46. what 3 ways can sharpness be optimized (by decrease beam penumbra)
46. 1.minimizing object-film distance (OFD) 2.maximizing source-image distance (SID) 3.decreasing focal spot size
47
47. subject contrast: chest - ? / abdomen - ? / extremities - ?
47. 1.chest - high subject contrast 2.abdomen - low subject contrast 3.extremities - intermediate (to high) subject contrast
48
48. how much of a change in mAs has to occur to produce a visual change in optical density?
48. 30% (kVp changed by approximately 4% to produce a visible change in O.D.)
49
49. what is important to know about radiations effect on water?
49. can split water & make free radicals. hydrogen peroxide formation (toxic). effects are enhanced when oxygen is present.
50
50. law of bergonie & tribondeau: what factors cause increased radiosensitivity?
50. decrease age, increased metabolic activity, cell proliferation rate, tissue growth rate
51
51. law of bergonie & tribondeau: how does cell maturity relate to resistance?
51. greater maturity of cell = increased resistance (*kids are very sensitive to radiation)
52
52. which 4 cell types are highly sensitive to radiation?
52. 1.lymphocytes 2.erythroblasts 3.myeloblasts 4.spermatogonia **foot is very radio resistant
53
53. ____ are among the most radiosensitive cells?
53. spermatogonia (gonad shield)
54
54. almost every type of chromosomal aberration can be ____
54. radiation induced (visible chromosomal damage)
55
55. ____ chromosomal aberrations are considered to be the most significant in terms of latent human damage
55. multi-hit
56
56. what is the minimum radiation dose necessary to produce chromosomal aberration?
56. 5 rad
57
57. what is the acute threshold of cataract formation?
57. 2 Gy (Beir suggests 0.6-1.5 Gy)
58
58. what are five long term areas of somatic damage?
58. 1.cataract formation 2.thyroid nodularity & CA 3.lifespan shortening 4.cancer induction 5.fetal effects
59
59. fetal effects: which trimester is most sensitive?
59. first trimester (maturity of fetus at time of exposure determines magnitude & kinds of damage )
60
60. a dose of 1.0 rem per generation increases the natural or spontaneous mutation rate by approximately ___
60. 0.01
61
61. distance: scatter is generally ___ of beam entrance skin intensity at ___ meter
61. 0.1% of beam entrance skin intensity at 1.0 meter (1 meter away is significant for dilution)
62
62. fetal exposure - 2nd to 8th week of pregnancy - Early: & Later:
62. early= severe skeletal anomalies & later= congenital abnormalities
63
63. fetal exposure - 8th to 15th week - structural CNS disorder
63. microcephaly
64
64. 3 ways for exposure reduction
64. 1.time (minimize) 2.distance (maximize) 3.shielding (employ)
65
65. lowers patient dose by restricting the volume of irradiated tissues (improves image contrast by decreasing scatter)
65. collimation (restricts primary beam)
66
66. 1 TVL (tenth value layer) = ___
66. 3.3 HVLs
67
67. what body parts contain high effective dose values?
67. 1.lumbar spine 2.barium enema
68
68. aprons: primary beam / secondary beam
68. primary: 0.5 mm / secondary: 0.25 mm
69
69. higher wavelength =
69. less energy
70
70. electrons enter the anode with similar kinetic energy, but exit in ____ have different ____
70. photons / energy values
71
71. doubling ___ will double the number of admitted xrays
71. mAs
72
72. why is higher kVp safer?
72. deposits less energy in the patient
73
73. know chart on page 7
73. seriously
74
74. know chart on page 15
74. quality factors
75
75. 4 factors of attenuation
75. 1.kilovoltage 2.density 3.atomic number (Z) 4.electrons per gram of tissue
76
76. 1sv = ____
76. 1sv = 100 rem
77
77. know optical density chart page 2
77. seriously
78
78. law of bergonie and tribondeau - page 6
78. seriously
79
79. cytogenic damage
79. damage is manifested during next cellular mitosis
