Unit 3: Scatter Control

Question 1

Scatter radiation is primarily the result of the _____________ ___________

Answer 1

Compton interaction

Question 2

Scatter is produced ________ the pt

Answer 2

inside

Question 3

Increased scatter adds _____________ ______

Answer 3

unwanted fog

Question 4

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

Answer 4

minimize

Question 5

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

Answer 5

kVp, irradiated tissue

Question 6

kVp affects the ______________ of the beam

Answer 6

penetrability

Question 7

The Amount of scatter radiation exiting the patient depends on ____

Answer 7

kVp

Question 8

As kVp increases, _______ photons undergo interactions with matter

Answer 8

fewer

Question 9

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

Answer 9

compton

Question 10

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

Answer 10

greater

Question 11

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

Answer 11

greater

Question 12

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

Answer 12

greater

Question 13

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

Answer 13

greater

Question 14

The higher the atomic number, the ________ the scatter

Answer 14

lower

Question 15

What produces white on image?

Answer 15

complete absorption

Question 16

Bone absorbs _____ radiation and scatters ____ than soft tissue

Answer 16

more, less

Question 17

How do we control scatter radiation? (3)

Answer 17

Beam-restricting devices
Grids
COLLIMATION

Question 18

One purpose of beam restriction is to ____________________________

Answer 18

limit patient’s exposure

Question 19

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

Answer 19

reduces

Question 20

Beam restriction is positioned right below the _____________________

Answer 20

tube housing

Question 21

As beam restriction/collimation increases, field size ________

Answer 21

decreases

Question 22

As beam restriction/collimation increases, patient dose __________

Answer 22

decreases

Question 23

Decreasing field size, ____________ the quantity of scatter radiation

Answer 23

decreases

Question 24

increase collimation, __________ image contrast

Answer 24

increase

Question 25

increase field size, ___________ image contrast

Answer 25

decreases

Question 26

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

Answer 26

Aperture Diaphragms

Question 27

What is the simplest form of beam restriction device?

Answer 27

Aperture Diaphragms

Question 28

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

Answer 28

directly below x-ray tube

Question 29

What is the disadvantage to aperture diaphragms?

Answer 29

large area of unsharpness

Question 30

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

Answer 30

Cones and Cylinders

Question 31

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

Answer 31

directly below tube window

Question 32

Are cones and cylinders interchangeable among tube housings?

Answer 32

no

Question 32

Are cones and cylinders interchangeable among tube housings?

Answer 32

no

Question 33

Which beam restriction device creates a circular projected field?

Answer 33

cones and cylinders

Question 34

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

Answer 34

better

Question 35

When are cones and cylinders used?

Answer 35

Sinus exams Lateral L5-S1 Projection Nasal bones

Question 36

Which beam-restricting device is used most often?

Answer 36

collimators

Question 37

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

Answer 37

2-3

Question 38

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

Answer 38

aperture diaphragm

Question 39

The lead/bottom shutters have the ability to ________________________

Answer 39

adjust the size of the field

Question 40

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

Answer 40

upper

Question 41

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

Answer 41

bottom

Question 42

Parts to collimator box (3)

Answer 42

shutters light source/mirror plastic template w/ crosshairs

Question 43

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

Answer 43

2%

Question 44

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

Answer 44

1%

Question 45

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

Answer 45

automatic collimators

Question 46

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

Answer 46

larger

Question 47

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

Answer 47

less, increased

Question 48

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

Answer 48

25-50%

Question 49

lead blockers and lead masks are considered ____________ devices

Answer 49

Ancillary

Question 50

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

Answer 50

ancillary devices

Question 50

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

Answer 50

ancillary devices

Question 51

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

Answer 51

more

Question 52

PBL

Answer 52

positive beam limitation

Question 53

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

Answer 53

mAs