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Exam 2 Flashcards

1
Q

Which tube will dissipate heat better?

A

Tube with the larger FSS and larger angle

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2
Q

Which tube has largest Effective FSS?

A

Pick tube with the largest angle

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3
Q

What amperage does thermoionic emission take place?

A

between 3-5 so 4 would be “best answer”

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4
Q

Focusing cup in the cathode must be what electrical charge?

A

Negative

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5
Q

When is focusing cup positive?

A

When you want short exposure time with grid x-ray- usually used in interventional therapy

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6
Q

Increasing anode angle from 7 –> 15 causes a(n) _____ in the EFSS?

A

Increase

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7
Q

What is the Heel Effect?

A

CR intensity will be greater towards cathode side and less intense towards anode side because electrons have to travel through more material in anode so they are weaker

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8
Q

Where do you place the patient in relation to anode/cathode side?

A

Thicker parts under cathode side and thinner under anode

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9
Q

What does a small focal spot and a small Field Of View (FOV) make more prominent?

A

The darkness scale is more prevalent in images with a small FSS and a small FOV

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10
Q

When do you see the Heel Effect the most? 3 things..

A
  • small focal spot
  • shorter SID
  • larger film size
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11
Q

What could damage the tube? 3 things..

A
  • high exposure without warmup
  • long exposure time could melt it
  • filament vaporization, some point filament will crack
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12
Q

What three things are built in to the machine to keep the machine from breaking?

A
  • anode cooling chart
  • housing cooling chart
  • radiographic cooling chart
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13
Q

What number to remember in formula for 3 phase 6 pulse heat calculation?

A

1.35

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14
Q

What number to remember in formula for 3 phase 12 pulse heat calculation?

A

1.41

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15
Q

How do we cool the tube? 2 ways..

A

oil and a fan

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16
Q

What are the 2 types of xrays produced?

A

Characteristic and Brem’s

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17
Q

We send electrons across with KE. The more kVp you select, the more…

A

energy across the tube

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18
Q

Every 100 electrons that cross the tube, how many actually produce an xray?

A

1%, 99% converted to heat

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19
Q

Amount of heat is ____ related to the amount of electrons.

A

directly related, MA^, H^

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20
Q

What is the typical diagnostic range for kVp?

A

50 kVp-150 kVp

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21
Q

As you increase kVp, you are ___ amount of xrays, similarly producing more ___ interaction instead of ____ interactions.

A

increasing, xray, heat

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22
Q

What kVp level must occur for Characteristic xrays to occur?

A

69 kVp and up

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23
Q

What is the formula to calculate Characteristic xray?

A

binding energy from shell that electron was taken from from the binding energy of the new shell

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24
Q

What shell gives USEFUL interaction?

A

k

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25
What is quality in an xray?
kEv
26
What gives you max xray interaction?
When the electron crashes into the nucleus head on and gives off 100% of its energy
27
What is the kEv in tungsten to create characteristic?
69/70 kEv
28
To increase the KE of an electron, you can change the what?
e- velocity, AKA kVp
29
What % of electrons reaching the anode create xray?
1%
30
Characteristic xray requires what to occur?
Electron removal from an atom
31
Brem's radiation production at 70 kVp accounts for what % of beam?
85%, 15% is characteristic
32
What is an emission spectrum?
graphical representation of an xray
33
What do you look at in an emission spectrum to determine max kVp output?
The end kVp on the chart
34
When kVp increases or decreases, what is directly proportional to it?
of xray photons
35
___ % increase in kV equals ___ of mAs
15, doubling
36
Higher kVp and more energetic xrays, means what for the patient?
More are penetrating the patient
37
What 3 things are inherent filters in the xray tube? What are their numbers?
- window, 1.0 mm AlEq - oil - mirror, 1-1.5mm AlEq
38
What is the FDA requirement for amount of aluminum equivalent required for attenuation?
2.5mm
39
Number of xrays coming out on anode side is ___ with more filtration?
less
40
What does filtration look like on a chart?
filtration= amplitude DOWN, and shift to the RIGHT
41
What is it termed when there are less xrays in the beam, but has a higher energy?
Hard beam
42
For anodes, what material is used in the center for most attraction?
Tungsten, because high Z#, the higher the Z#, the more attraction and more energy
43
What happens to the graph when kVp is increased?
The amplitude goes down and the graph shifts to the right
44
What happens to the graph when you just change mAs?
Only the amplitude changes
45
An xray beam may be termed as which of the following?
Polyenergetic
46
The emission spectrum cross the x axis at what % of the kVp?
100% (last number on the graph= input kVp)
47
An increase in the amp of emission spectrum only indicates increase in ____?
mAs
48
How many half-value layers must be added to the primary beam to reduce its intensity to less than 20% of the original value>
3
49
Which of the following is affected by half-layer value?
patient exposure
50
The amount of material that will reduce the intensity of the primary beam to one-half its original value is?
half-layer value
51
Which of the following are useful as a filter?
aluminum, oil, glass
52
The types of target interaction that occurs in the production of diagnostic range xray photons are dependent upon...?
electron KE
53
The transfer of incident electrons' KE to the outer shell electrons causing vibration of the outer shell electron results in emission of what?
infrared radiation
54
Almost all of the KE of the incident electrons is converted to ____.
heat
55
What type of voltage is required for portable units?
3 phase voltage
56
How far do electrons usually travel into the tube target?
.5mm
57
What is 1 R in mGy?
10mGy
58
The kVp is on the X axis- what does it represent? Quality or quantity?
Quality
59
Where is the peak shown on the graph for characteristic radiation?
69 kEv
60
The quantity of the xray beam is described as its ___.
intensity
61
What are the two elements used for mammography?
Molybdenum and Rhodium
62
What is the typical intensity of a diagnostic xray beam?
.05mGy
63
Xray quantity is ____ to mAs.
directly proportional
64
T/F Increasing mAs does not increase xray efficiency.
True

Physics Exam 2 (1 decks)

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