5. Filtration

Question 1

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

Answer 1

Filtration

Question 2

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

Answer 2

hardening the beam

Question 3

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

Answer 3

20

Question 4

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

Answer 4

50

Question 5

Significant soft-tissue penetration

occurs between ____ keV

Answer 5

30-40

Question 6

Any material designed to selectively absorb photons

from the x-ray beam is called a

Answer 6

filter

Question 7

is the most common filter material used

Answer 7

Aluminum

Question 8

Other materials : ______ (4) are used to

become filters in various instances.

Answer 8

glass, oil, copper, and tin

Question 9

is considered the standard filtering material

Answer 9

Aluminum

Question 10

is also expressed in terms of half-value layer

Answer 10

Filtration

Question 11

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

Answer 11

half-value layer (HVL)

Question 12

TYPES OF FILTRATION

Answer 12

Inherent,
Added,
Compound,
Compensation

Question 13

occurs at various points between the x-ray

tube and the image receptor

Answer 13

Filtration

Question 14

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

Answer 14

inherent filtration

Question 15

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

Answer 15

inherent filtration

Question 16

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

Answer 16

0.5-1.0 mm Al/Eq

Question 17

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

Answer 17

gassy,
pit,
vaporized metal

Question 18

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

Answer 18

added filtration

Question 19

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

Answer 19

low-energy,

maximum

Question 20

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

Answer 20

added filtration

Question 21

uses two or more materials that

complement one another in their absorbing abilities

Answer 21

Compound filter

Question 22

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

Answer 22

highest,

lowest

Question 22

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

Answer 22

copper

Question 23

is usually designed to solve a

problem involving unequal subject densities

Answer 23

Compensating filter

Question 24

The 2 most popular compensating filters are the

Answer 24

wedge filter and the trough filter

Question 25

sometimes called a double wedge

Answer 25

trough filter

Question 26

is useful to even the density differences
between the mediastinum and the lungs on a chest
radiograph

Answer 26

Trough filter

Question 27

can be useful for procedures on the thoracic spine, the feet and the lower extremities (e.g. venography and femoral angiography)

Answer 27

Wedge filter

Question 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

Answer 29

Total filtration

Question 29

recommends minimum filtration levels for diagnostic radiography

Answer 29

The National Council on Radiation Protection and Measurements

Question 30

aluminum filters of ____ absorb significant percentages of photons below the diagnostic range while permitting the vast majority to pass

Answer 30

1-3 mm

Question 31

Below 50 kVp (Minimum Total Filter)

Answer 31

0.5 mm aluminum

Question 32

50-70 kVp (Minimum Total Filter)

Answer 32

1.5 mm aluminum

Question 33

Above 70 kVp (Minimum Total Filter)

Answer 33

2.5 mm aluminum

Question 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)

Answer 34

useful beam

Question 35

The _____ and _____ has a great impact on recorded detail

Answer 35

overall size,

placement

Question 35

all filtration can be expressed in terms of the thickness of _________

Answer 35

aluminum equivalency (Al/Eq)

Question 36

To compensate for the loss of exposure when filtration is increased, technical factors must be _____ to maintain the same image receptor exposure

Answer 36

increased