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RS 205: Image Production & Management > Unit 3: Scatter Control > Flashcards

Unit 3: Scatter Control Flashcards

1
Q

Scatter radiation is primarily the result of the _____________ ___________

A

Compton interaction

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2
Q

Scatter is produced ________ the pt

A

inside

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3
Q

Increased scatter adds _____________ ______

A

unwanted fog

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4
Q

In order to provide the best possible image, the radiographer must try to __________ the amount of scatter radiation reaching the IR

A

minimize

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5
Q

The two factors affecting the amount and energy of scatter are _______ and __________

A

kVp, irradiated tissue

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6
Q

kVp affects the ______________ of the beam

A

penetrability

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7
Q

The Amount of scatter radiation exiting the patient depends on ____

A

kVp

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8
Q

As kVp increases, _______ photons undergo interactions with matter

A

fewer

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9
Q

For the photons that do undergo interactions when kVp is increased, a greater percentage undergo _________ interactions

A

compton

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10
Q

Using higher kVp produces a ________ proportion of higher-energy scattered x-rays compared to lower kVp

A

greater

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11
Q

Larger the beam field size, the _________ the amount of scatter produced

A

greater

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12
Q

The thicker the part being imaged, the _______ the amount of scatter produced

A

greater

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13
Q

The higher the atomic number, the _______ the number of photoelectric absorption interactions

A

greater

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14
Q

The higher the atomic number, the ________ the scatter

A

lower

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15
Q

What produces white on image?

A

complete absorption

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16
Q

Bone absorbs _____ radiation and scatters ____ than soft tissue

A

more, less

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17
Q

How do we control scatter radiation? (3)

A

Beam-restricting devices
Grids
COLLIMATION

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18
Q

One purpose of beam restriction is to ____________________________

A

limit patient’s exposure

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19
Q

Purpose: beam restriction ____________ the amount of scatter radiation produced within the patient

A

reduces

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20
Q

Beam restriction is positioned right below the _____________________

A

tube housing

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21
Q

As beam restriction/collimation increases, field size ________

A

decreases

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22
Q

As beam restriction/collimation increases, patient dose __________

A

decreases

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23
Q

Decreasing field size, ____________ the quantity of scatter radiation

A

decreases

24
Q

increase collimation, __________ image contrast

A

increase

25
Q

increase field size, ___________ image contrast

A

decreases

26
Q

What is a Flat piece of lead (diaphragm) that has a hole (aperture) in it?

A

Aperture Diaphragms

27
Q

What is the simplest form of beam restriction device?

A

Aperture Diaphragms

28
Q

Where are aperture diaphragms placed in relation to the x-ray tube?

A

directly below x-ray tube

29
Q

What is the disadvantage to aperture diaphragms?

A

large area of unsharpness

30
Q

What is essentially an aperture diaphragm that has an extended flange attached to it?

A

Cones and Cylinders

31
Q

Where are cones and cylinders placed in relation to the x-ray tube?

A

directly below tube window

32
Q

Are cones and cylinders interchangeable among tube housings?

A

no

32
Q

Are cones and cylinders interchangeable among tube housings?

A

no

33
Q

Which beam restriction device creates a circular projected field?

A

cones and cylinders

34
Q

A cylinder is ________ at limiting un-sharpness
than a cone

A

better

35
Q

When are cones and cylinders used?

A

Sinus exams
Lateral L5-S1 Projection
Nasal bones

36
Q

Which beam-restricting device is used most often?

A

collimators

37
Q

Collimators have __________ sets of lead shutters that change the size and shape of the primary beam

A

2-3

38
Q

The entrance shutters within the collimators, limit x-ray beam much like the ____________ _________ would

A

aperture diaphragm

39
Q

The lead/bottom shutters have the ability to ________________________

A

adjust the size of the field

40
Q

Which shutters reduce the amount of off-focus radiation from reaching the IR by absorbing this radiation before it exits the tube?

A

upper

41
Q

Which shutters reduce the penumbra along the periphery of the beam?

A

bottom

42
Q

Parts to collimator box (3)

A

shutters
light source/mirror
plastic template w/ crosshairs

43
Q

During a quality control check, the collimator misalignment should be less than ___ of the SID used.

A

2%

44
Q

During a quality control check, the perpendicularity of the CR must be less than or equal to __ misaligned

A

1%

45
Q

What was required by law for many years before it was no longer made as a requirement?

A

automatic collimators

46
Q

automatic collimators make it difficult for the radiographer to increase the size of the primary beam to a field_________ than the IR

A

larger

47
Q

When the beam is restricted, _______ scatter radiation will reach the image receptor, technical factors may need to be __________ to compensate for the reduction in the overall image receptor exposure

A

less, increased

48
Q

Typically increased ________ of the mAs to compensate for the reduction in field size

A

25-50%

49
Q

lead blockers and lead masks are considered ____________ devices

A

Ancillary

50
Q

Which device helps absorb scatter that is produced in the soft tissue?

A

ancillary devices

50
Q

Which device helps absorb scatter that is produced in the soft tissue?

A

ancillary devices

51
Q

Digital IRs are ______ sensitive to lower-energy
levels of radiation

A

more

52
Q

PBL

A

positive beam limitation

53
Q

When making a significant increase in collimation, what should be increased?

A

mAs

RS 205: Image Production & Management (2 decks)

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