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Pre Exposure > Filtration Chapter 11 > Flashcards

Filtration Chapter 11 Flashcards

1
Q

What is FILTRATION?

A

Process of eliminating unwanted low energy Xray photons by insertion of absorbing materials into the primary beam

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2
Q

What is the PURPOSE of filtration?

A

-To protect the patient by removing low energy photons that would of otherwise contribute to patient dose

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3
Q

Do low energy photons contribute to image quality?

A

No

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4
Q

After filtering an emission spectrum chart what is the after effect?

A

-Peak energy did not change
-Low energy photons removed
-Decrease in total amount of photons
-Average energy increased
-Made it harder and stronger

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5
Q

What is another definition for flirtation?

A

A process of increasing the average energy of Xray beam by taking out low energy xrays (hardening)

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6
Q

What is poly-energetic x ray beam?

A

its beam of many different energies

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7
Q

Why is an xray beam hetergenous?

A

because not all xrays are the same energies. Thats why they are Poly energetic

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8
Q

Why do we insert filtration into the primary beam?

A

To protect the patients by removing low energy photons

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9
Q

The number of photons is what?

A

the intensity or quantity

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10
Q

How can filtration material be expressed as?

A

Aluminum Equivalent (AL/Eq)

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11
Q

What is the standard filtering material?

A

Aluminum

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12
Q

What is Half-Value Layer?

A

the amount of filtration needed to reduce the beam to one half of its original intensity

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13
Q

What is the amount of filtration required by law with a operating range BELOW 51?

A

0.5mm aluminum

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14
Q

What is the amount of filtration required by law with a operating range of 51 to 70?

A

1.5mm aluminum

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15
Q

What is the amount of filtration required by law with a operating range ABOVE 70?

A

2.5mm aluminum

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16
Q

What are the types of filtration? (5)

A

Inherent
Added
Compound
Compensating
Total

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17
Q

What is inherent filtration?

A

A filtration that is the result of composition of the tube and housing

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18
Q

What contributes to the inherent filtration?

A

-thickness of the glass envelope
-dielectric oil
-the glass window of the xray tube housing

19
Q

What is the typical x-ray tube total inherent filtration?

A

0.5-1mm AL/Eq

20
Q

Why does tube aging increase inherent filtration?

A

because of vaporized tungsten

21
Q

What is ADDED FILTRATION?

A

Any filtration outside of the tube and housing

22
Q

NOTE
(Added filter)

A

Material are selected to absorb as many low energy photons as possible while transmitting maximum number of high energy photons

23
Q

NOTE
(Added filter)

A

-Collimator averages about 1mm AL/Eq that most comes from sliver in the mirror
-1mm AL/Eq is added to exit port

24
Q

What is TOTAL FILTRATION?

A

Its the sum of inherent and added filtration

25
Q

Inherent + Added =

A

Total

26
Q

The total does not include any

A

compound or compensating filters that may be added later

27
Q

What is compound filtration?

A

Uses two or more materials in one filter that complement one another in their absorbing abilities

28
Q

How are compound filter constructed?

A

Each layer absorbs characteristic photons created by pervious layer

29
Q

A compound filter is also referred to as a

A

K-edge filter

30
Q

Compound filters place the highest atomic number material closes to…

A

the tube

31
Q

The lowest atomic number material is closet to the

A

patient

32
Q

What is the final layer for compound filter?

A

Aluminum

33
Q

The layer farthest from the patient and closest to the source is?

A

Copper

34
Q

What is the atomic number and thickness of copper?

A

-29
- .25mm

35
Q

What is the atomic number and thickness of aluminum?

A

-13
-1mm thick

36
Q

What is the copper filter backed up by?

A

Aluminum filter

37
Q

What is Compensating filter?

A

designed to solve a problem involving unequal subject densities

38
Q

What is the reason for an compensate filter?

A

Compensate an unequal absorption within the subject thus making the absorption of the primary beam more equal

39
Q

Compensating filter can be made of

A

-aluminum
-plastic
-saline solution bag
-leaded plastic trademarked under the -name ClearPb

40
Q

Note

A

Compensate filter is also for producing a more uniform image receptor exposure

41
Q

What are the two most popular compensating filter?

A

wedge and trough filter

42
Q

What are effects on tube output?

A

Ideally filtration would remove low energy photons however…

43
Q

Some high energy photons are removed which result in…

A

a decrease in radiographic exposure that must be compensated for with an increase in technique

44
Q

Note

A

Even though the technique needs to be increased to maintain the exposure there is still a decrease in patient dose because of the removal of lower energy photons

Pre Exposure (10 decks)

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