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
Q
- what does film density = ?
A
- film density = film blackness (air = black)
26
Q
- what happens if you increase atomic #?
A
- increase quantity and quality
27
Q
- 2 basic factors affecting quality of x-ray beam photons?
A
- 1.kilovoltage (kVp) 2.filtration
28
Q
- what are 3 ways energy (radiation) is transferred to any material which it interacts?
A
- 1.penetrates 2.absorbed 3.scattered
29
Q
- 4 factors affecting attenuation?
A
- 1.kilovoltage (faster cars) 2.density 3.atomic number (Z) 4.electrons per gram of tissue
30
Q
- measures the amount of radiation energy (E) absorbed per unit mass (M) of the absorbing medium
A
- absorbed dose (D) = (E) / (M)
31
Q
- 1 Gy = ____
A
- 1 Gy = 100 rads
32
Q
- 1 rad = ____
A
- 1 rad = 10 mGy
33
Q
- 1 Sv = ____
A
- 1 Sv = 100 rem (1 rem = 10 mSv)
34
Q
- what is silver (Ag+1) reduced to?
A
- 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
Q
- converts silver halide crystals with latent image centers into ________
A
- flecks of silver
36
Q
- activators: ______ provides acid media (pH 4.0) for hardener & also helps neutralize developer
A
- acetic acid
37
Q
- film types: are non-screen films enhanced x-ray sensitivity or enhanced light sensitivity?
A
- enhanced x-ray sensitivity
38
Q
- how does a fluoroscope work?
A
- produces a real-time image (know that it is an inverted ( - ) image. areas that look dark are light)
39
Q
- what kind of light does silver halide respond to?
A
- violet & blue (not green, yellow or red)
40
Q
- digital radiography replaces film with reusable detector. what are they 2 types of systems?
A
- 1.cassette-based 2.cassette-less
41
Q
- what 3 things does scattered radiation increase with?
A
- 1.increasing part thickness 2.increased field size 3.increased energy (kVp) of x-rays
42
Q
- at a transmittance (T%) of 50% what is the optical film density?
A
- 0.3
43
Q
- if you increase kilovoltage how does that affect contrast?
A
- increases contrast
44
Q
- does changing miliamps affect contrast?
A
- no (*note: mA x time (mAs) does not affect subject contrast either
45
Q
- any degree of darkening on the film that occurs outside exposure process is ____?
A
- fog
46
Q
- what 3 ways can sharpness be optimized (by decrease beam penumbra)
A
- 1.minimizing object-film distance (OFD) 2.maximizing source-image distance (SID) 3.decreasing focal spot size
47
Q
- subject contrast: chest - ? / abdomen - ? / extremities - ?
A
- 1.chest - high subject contrast 2.abdomen - low subject contrast 3.extremities - intermediate (to high) subject contrast
48
Q
- how much of a change in mAs has to occur to produce a visual change in optical density?
A
- 30% (kVp changed by approximately 4% to produce a visible change in O.D.)
49
Q
- what is important to know about radiations effect on water?
A
- can split water & make free radicals. hydrogen peroxide formation (toxic). effects are enhanced when oxygen is present.
50
Q
- law of bergonie & tribondeau: what factors cause increased radiosensitivity?
A
- decrease age, increased metabolic activity, cell proliferation rate, tissue growth rate
51
Q
- law of bergonie & tribondeau: how does cell maturity relate to resistance?
A
- greater maturity of cell = increased resistance (*kids are very sensitive to radiation)
52
Q
- which 4 cell types are highly sensitive to radiation?
A
- 1.lymphocytes 2.erythroblasts 3.myeloblasts 4.spermatogonia **foot is very radio resistant
53
Q
- ____ are among the most radiosensitive cells?
A
- spermatogonia (gonad shield)
54
Q
- almost every type of chromosomal aberration can be ____
A
- radiation induced (visible chromosomal damage)
55
Q
- ____ chromosomal aberrations are considered to be the most significant in terms of latent human damage
A
- multi-hit
56
Q
- what is the minimum radiation dose necessary to produce chromosomal aberration?
A
- 5 rad
57
Q
- what is the acute threshold of cataract formation?
A
- 2 Gy (Beir suggests 0.6-1.5 Gy)
58
Q
- what are five long term areas of somatic damage?
A
- 1.cataract formation 2.thyroid nodularity & CA 3.lifespan shortening 4.cancer induction 5.fetal effects
59
Q
- fetal effects: which trimester is most sensitive?
A
- first trimester (maturity of fetus at time of exposure determines magnitude & kinds of damage )
60
Q
- a dose of 1.0 rem per generation increases the natural or spontaneous mutation rate by approximately ___
A
- 0.01
61
Q
- distance: scatter is generally ___ of beam entrance skin intensity at ___ meter
A
- 0.1% of beam entrance skin intensity at 1.0 meter (1 meter away is significant for dilution)
62
Q
- fetal exposure - 2nd to 8th week of pregnancy - Early: & Later:
A
- early= severe skeletal anomalies & later= congenital abnormalities
63
Q
- fetal exposure - 8th to 15th week - structural CNS disorder
A
- microcephaly
64
Q
- 3 ways for exposure reduction
A
- 1.time (minimize) 2.distance (maximize) 3.shielding (employ)
65
Q
- lowers patient dose by restricting the volume of irradiated tissues (improves image contrast by decreasing scatter)
A
- collimation (restricts primary beam)
66
Q
- 1 TVL (tenth value layer) = ___
A
- 3.3 HVLs
67
Q
- what body parts contain high effective dose values?
A
- 1.lumbar spine 2.barium enema
68
Q
- aprons: primary beam / secondary beam
A
- primary: 0.5 mm / secondary: 0.25 mm
69
Q
- higher wavelength =
A
- less energy
70
Q
- electrons enter the anode with similar kinetic energy, but exit in ____ have different ____
A
- photons / energy values
71
Q
- doubling ___ will double the number of admitted xrays
A
- mAs
72
Q
- why is higher kVp safer?
A
- deposits less energy in the patient
73
Q
- know chart on page 7
A
- seriously
74
Q
- know chart on page 15
A
- quality factors
75
Q
- 4 factors of attenuation
A
- 1.kilovoltage 2.density 3.atomic number (Z) 4.electrons per gram of tissue
76
Q
- 1sv = ____
A
- 1sv = 100 rem
77
Q
- know optical density chart page 2
A
- seriously
78
Q
- law of bergonie and tribondeau - page 6
A
- seriously
79
Q
- cytogenic damage
A
- damage is manifested during next cellular mitosis
