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APPH 226 > Midterm Review > Flashcards

Midterm Review Flashcards

1
Q

What happens when mAs is increased on an x-ray emission spectrum?

A

-increase in amplitude

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2
Q

What happens when kVp is increased on the x-ray emission spectrum ?

A
  • increase in amplitude
  • increase average energy
  • increased peak energy (end point on curve)
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3
Q

What happens with a higher atomic number of target material on the x-ray emission spectrum?

A
  • increased amplitude
  • increased average energy
  • different characteristic spectrum
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4
Q

What happens with a higher voltage waveform on the x-ray emission spectrum?

A
  • increase amplitude

- increase average energy

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5
Q

What happens to the x-ray emission spectrum when filtration is added?

A
  • decreased amplitude

- increased average energy

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6
Q

Describe characteristic radiation

A

When the projectile electron interacts with an inner shell electron and removes it from the atom. An outer shell electron then replaces the empty spot, and energy is given off in the form of characteristic radiation

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7
Q

Which characteristic x-rays of tungsten are useful for imaging?

A

K-characteristic. The characteristic x-rays produced from other inner shells are at an energy level that is too low for diagnostic purposes

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8
Q

What is another name for the characteristic spectrum?

A

The discrete emission spectrum

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9
Q

What type of x-rays form a continuous emission spectrum?

A

Bremsstrahlung x-rays

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10
Q

How does bremsstrahlung radiation occur?

A

The projectile electron interacts with the nuclear field of an atom, and when it changes direction, it loses kinetic energy in the form of radiation

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11
Q

How does adding filtration affect patient dose?

A

It reduces it, because the low energy x-rays that are absorbed by the patient are removed from the x-ray beam

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12
Q

What effect do Compton interactions have on image quality?

A

It produces scatter, which degrades the image quality and reduces image contrast. Any time that more scatter is produced, image quality is decreased

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13
Q

How does body habitus affect radiographic density?

A

The larger the patient, the less radiographic density will be on the image due to exponential attenuation

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14
Q

What effect do Compton interactions have on radiographic density?

A

Scatter contributes to the radiographic density on the image, as it is additional photons that make it onto the image

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15
Q

When kVp is increased:

A

⬆️ radiographic density
⬆️ scatter
⬇️ patient dose

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16
Q

When mAs is increased:

A

⬆️ radiographic density
scatter: no change
⬆️ patient dose

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17
Q

When x-ray energy is increased:

A

⬆️ Total interactions
⬆️ compton interactions
⬇️ PE interactions

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18
Q

When OID is increased:

A

⬇️ radiographic density
⬇️ scatter
patient dose: no change

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19
Q

When atomic number is increased:

A

compton interactions: no change
⬆️ PE interactions
⬇️ transmission

20
Q

When SID is increased:

A

⬇️ radiographic density

scatter: no change

21
Q

When focal spot size is increased:

A

Radiographic density: no change
Scatter: no change
Patient dose: no change

22
Q

When collimating is decreased: (larger light field)

A

⬆️ radiographic density
⬆️ scatter
⬆️ patient dose

23
Q

What is the minimum change in mAs required in order to produce a visible effect on the image?

A

30%

24
Q 
An x-ray tube with a stationary anode:
A) incorporates the line-focus principle
B) limits leakage radiation
C) provide for greater heat dissipation 
D) usually has a very small focal spot
A

A! Incorporates the line focus principle

25
Q

Why does the anode heel effect occur?

A

It is a consequence of the line focus principle, x-ray photons produced on the anode side must transverse a greater thickness of target material than the x-rays on the cathode side

26
Q

the main reason for using the line-focus principle is

A

To decrease the size of the actual focal spot

27
Q

What happens when a two step exposure button is pressed?

A
  • during the first step, the rotor accelerates and the filament is heated (forming electron cloud)
  • during the second step, the kVp is applied and electrons travel to the anode where x-rays are created
28
Q

What type of charge is placed on the focusing cup and why?

A

Focusing cup is negatively charged, so that it can “focus” the electrons beam to a small area on the anode. Its negative charge pushes the electrons closer together

29
Q

X-rays are emitted through an opening in the glass envelope called a port (true/false)

A

False! There isn’t an actual opening, just a thinned out area

30
Q

The smaller the anode angle, the _______ the heel effect

A

The larger the heel effect

31
Q

The smaller the IR, the _______ heel effect

A

The smaller the heel effect

32
Q

The longer the SID, the ______ the heel effect

A

The smaller the heel effect

33
Q

What is the auto transformer sometimes referred to as and why?

A

Can be referred to as the kVp selector as it directly impacts the voltage being supplied to the primary side of the step up transformer. When the kVp is selected on the console, it controls the auto transformer

34
Q

What type of current does the step up transformer require?

A

Alternating current (AC)

35
Q

What type of current does the x-ray tube require, and why?

A

Direct current (DC), as the electron flow must go in one direction (cathode to anode)

36
Q

What is the purpose of a rectifier?

A

Allows current to flow only in one direction, so depending on how rectifiers are aligned in a circuit, can control the direction of current flow. “One way valves”

37
Q

Why is a high frequency generator more efficient at x-ray production as compared to a single phase generator?

A

Single phase generators have 100% ripple, meaning that the voltage fluctuates from 0 to max. X-rays are only produced near the peak voltage, so x-rays are not being produced during the entire voltage waveform. High frequency generators have 1% ripple, so the voltage only fluctuates between 99% and max, meaning x-ray production is happening the entire time of exposure

38
Q

what are the three types of beam restrictors?

A

Aperature diaphragm, cones/cylinders, and variable aperature collimator

39
Q

If a cone cylinder is not aligned with the x-ray source and interferes with the x-ray beam what is it referred to?

A

Cone cutting

40
Q

Which type of collimator is most effective at reducing image blur caused by off focus radiation?

A

Variable aperature collimator

41
Q

Does the use of PBL replace manual collimation?

A

No, it only adjusts the collimator to match the size of the IR. The tech will still need to adjust the collimation to restrict it to only the area of interest

42
Q

Which x-rays are transmitted through a grid?

A

Those that travel in the direction of the interspace. X-ray photons that scatter at a different angle through the interspace will be absorbed by the lead strips

43
Q

Grid lines will be more apparent with

A

Low grid frequency

44
Q

How is grid performance measured?

A

With the k factor (contrast improvement factor). Must be higher than 1 to indicate contrast improvement has occurred

45
Q

A synonym for grid factor is

A

Bucky factor

46
Q

True or false: grid cut off will always occur with parallel grids

A

TRUE

47
Q

Which grid error(s) will result in the image appearing underexposed, decreased density across the image?

A
  • off level

- off center

APPH 226 (23 decks)

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