5. Filtration Flashcards

1
Q

is the process of eliminating undesirable low-energy x-ray photons by the insertion of absorbing materials into the primary beam

A

Filtration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Filtration is sometimes called ______ since it removes the low-energy (soft) photons.

A

hardening the beam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

At ____ keV, about 45% of the incident photons will penetrate 1 cm of soft tissue but only about 0.0006 percent will penetrate 15cm

A

20

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

at ____ keV, 3.5% of the incident photons (a significant percentage) will penetrate 15 cm

A

50

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Significant soft-tissue penetration

occurs between ____ keV

A

30-40

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Any material designed to selectively absorb photons

from the x-ray beam is called a

A

filter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

is the most common filter material used

A

Aluminum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Other materials : ______ (4) are used to

become filters in various instances.

A

glass, oil, copper, and tin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

is considered the standard filtering material

A

Aluminum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

is also expressed in terms of half-value layer

A

Filtration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

is that amount of absorbing material that will reduce the intensity of the primary beam to one-half its original value

A

half-value layer (HVL)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

TYPES OF FILTRATION

A

Inherent,
Added,
Compound,
Compensation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

occurs at various points between the x-ray

tube and the image receptor

A

Filtration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Filtration that is a result of the composition of the tube and housing is often called ________ because it is a part of these structures

A

inherent filtration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The thickness of the glass envelope of the tube, the dielectric oil that surrounds the tube, and the glass window of the housing all contribute to the

A

inherent filtration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

A typical x-ray tube might have a total inherent filtration of ______

A

0.5-1.0 mm Al/Eq

17
Q

As the tube ages they become _____, the anode begins to ___ and the glass envelope may gain a mild coating of _______

A

gassy,
pit,
vaporized metal

18
Q

Any filtration that occurs outside the tube and housing and before the image receptor is considered _______

A

added filtration

19
Q

Filtration materials are selected to absorb as many ____ photons as possible while transmitting a ______ number of high-energy photons

A

low-energy,

maximum

20
Q

The collimation device also adds filtration to the beam and is considered to be _______

A

added filtration

21
Q

uses two or more materials that

complement one another in their absorbing abilities

A

Compound filter

22
Q

Compound filters place the _____ atomic number material closest to the tube and the _____ atomic number material closest to the patient

A

highest,

lowest

22
Q

Although aluminum is the most common filtering
material, _____, with an atomic number of 29,
functions well for slightly higher energies

23
Q

is usually designed to solve a

problem involving unequal subject densities

A

Compensating filter

24
The 2 most popular compensating filters are the
wedge filter and the trough filter
25
sometimes called a double wedge
trough filter
26
is useful to even the density differences between the mediastinum and the lungs on a chest radiograph
Trough filter
27
can be useful for procedures on the thoracic spine, the feet and the lower extremities (e.g. venography and femoral angiography)
Wedge filter
29
is equal to the sum of inherent and added filtration and does not include any compound or compensating filters that may be added later
Total filtration
29
recommends minimum filtration levels for diagnostic radiography
The National Council on Radiation Protection and Measurements
30
aluminum filters of ____ absorb significant percentages of photons below the diagnostic range while permitting the vast majority to pass
1-3 mm
31
Below 50 kVp (Minimum Total Filter)
0.5 mm aluminum
32
50-70 kVp (Minimum Total Filter)
1.5 mm aluminum
33
Above 70 kVp (Minimum Total Filter)
2.5 mm aluminum
34
not only does filtration reduce the patient exposure dose by eliminating low-energy photons from the primary beam, it also removes a portion of the _______ (EFFECT ON OUTPUT)
useful beam
35
The _____ and _____ has a great impact on recorded detail
overall size, | placement
35
all filtration can be expressed in terms of the thickness of _________
aluminum equivalency (Al/Eq)
36
To compensate for the loss of exposure when filtration is increased, technical factors must be _____ to maintain the same image receptor exposure
increased