The automatic collimator

automatically collimates to the IR size.

The cathode includes the

filaments and the focusing cup.

Which of the following is true regarding the effect of mAs on the brightness of a digital image?

mAs does not affect brightness in a digital image.

What is the relationship between kVp and subject contrast?

high kVp creates low subject contrast.

The probability of a Compton interaction occurring is related to

the energy of the x-ray photon.

Grids absorb scatter radiation because the scattered photons

travel in the same direction as the transmitted photons.

Using excessive kVp w a dig IR results in 1. increased IR expos2. increased scatter reaching IR 3. decreased contrast

increased IR exposure, increased scatter reaching IR, decreased contrast.

Which of the following is the formula used to determine grid ratio?

Grid ratio = height of the lead strips/distance between the lead strips.

For a lateral lumbar spine, placing a lead shield on the table behind the area of exposure

reduces the scatter reaching the IR.

A grid with lead strips that run parallel to each other is a

parallel grid and nonfocused grid

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LRA 222 Final review

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Questions 83

Answers

1
The field shape produced by a collimator is
rectanglar
all of these
round
oval
2
Which of the following is not a primary exposure technique factor?
MA
time of exposure
kVp
SID
3
To maintain the same exposure to the IR, if the SID is increased, the mAs must be
doubled
decreased
left the same
increased
4
The only grid cutoff error that can occur with a parallel grid is
off-center
off-focus
upside down focused
off-level
5
The automatic collimator
automatically collimates to the IR size.
automatically collimates to the anatomy of interest.
is seldom found on modern x-ray equipment.
is required by law on all new equipment.
6
The distance between the grid and the convergent line is the
convergent point
covergent line
focal distance
focal range
7
The focusing cup is able to keep the electrons together because
opposite charge attract
opposite charges repel
like charges attract
like charges repel
8
When the x-ray beam is angled across the lead strips you have _________ cutoff.
off-focus
off-center
upside-down focused
off-level
9
The cathode includes the
filaments
filaments and the focusing cup.
focusing cup.
envelope.
10
The device used to absorb scatter radiation in the radiation leaving the patient before it reaches the image receptor is
cassette
flat panel detector
grid
filter
11
Grids are typically used:1. Part measures > 10 cm2. At least 60 kVp needed for exam3. Part transmits little scatter rad
1 and 2
1 and 3
2 and 3
1, 2, and 3
12
The relationship between the height of the lead strips and the distance between them is the grid
ratio
rating
number
frequency
13
The rate of flow of electrons passing through the x-ray tube during an exposure is
filament circut
tube current
kVp
Hz
14
Which of the following factors need to be considered when determining the grid to be used for a specific examination?
Patient exposure
all of these
focal range
Level of contrast improvement needed
15
Reducing the amount of scatter radiation reaching the IR results in
higher radiographic contrast.
reduced spatial resolution.
lower radiographic contrast.
improved spatial resolution.
16
The timer circuit is found on the
filament circut
primary circut
secondary circut
none of these
17
Prepping the rotor but not making an exposure on a regular basis is related to tube damage or failure.
False
True
18
Grids absorb almost all of the scatter radiation and allow all of the transmitted photons to pass through to the IR.
True
False
19
Which of the following occurs first in the sequence of events leading to x-ray production?
Anode and cathode become positively and negatively charged.
AC is converted to DC.
Electrons flow from cathode to anode.
Voltage becomes kilovoltage.
20
The beam-restriction device that results in images with the most unsharpness around the edge of the image is the
collimator
none of these
aperture diaphragm
cone and cylinder
21
To compensate for some of loss of spatial res due to large OID used with air gap technique, the __ should be incr also
grid ratio
grid ratio and SID
focal spot size
SID
22
Which of the following is true regarding the effect of mAs on the brightness of a digital image?
mAs does not affect brightness in a digital image.
doubling the mAs will increase brightness.
halfing the mAs will decrease brightness.
doubling the mAs will inc brightness & 1/2 the mAs will dec brightness
23
The primary side of the high-voltage transformer is found on the
none of these
secondary circut
filament circut
primary circut
24
The most effective and often used radiographic beam-restriction device is the
collimator
cone or cylinder
aperture diaphragm
none of these
25
Which of the following statements is true regarding practices to minimize patient exposure?
none of these
Use more mAs in dig img bc brightness is comp adjusted & it reduces noise
Grids should be used as much as possible to improve contrast.
The beam should be open as large as the image receptor being used.
26
A significant amount of collimation will have what effect on the amount of radiation reaching the IR
increased
none of these
reduced
the same
27
The air gap technique is based on creating a gap by increasing the ______.
SID
OID
mAs
SOD
28
Which of the following produces the greatest amount of scatter radiation exiting the patient?
Low kVp and small field size.
Low kVp and large field size
High kVp and small field size
High kVp and large field size
29
When using auto collimation, collimating to anatomy of interest is an unnecess waste of time; beam is already collimated
True
False
30
To overcome the decrease in sharpness caused by the air gap technique, an increase in SID is required.
False
True
31
What is the relationship between kVp and subject contrast?
high kVp creates low subject contrast.
low kVp creates low subject contrast.
kVp does not affect subject contrast.
high kVp creates high subject contrast.
32
The probability of a Compton interaction occurring is related to
all of these
the energy of the x-ray photon.
the mAs used
the atomic number of the matter.
33
To compensate for the reduction of radiation reaching the IR when a grid is used, ___________ is typically increased.
AID
kVp
OID
mAs
34
If 24 mAs and a 6:1 grid results in an excellent radiographic image, how much mAs is needed with a 5:1 grid?
36 mAs
16 mAs
28.8 mAs
20 mAs
35
The number of lead lines per inch or centimeter is the grid
frequency
number
rating
ratio
36
Grids absorb scatter radiation because the scattered photons
have extremely high energy
travel in the same direction as the transmitted photons.
have extremely low energy.
travel at an angle to the transmitted photons.
37
Using excessive kVp w a dig IR results in 1. increased IR expos2. increased scatter reaching IR 3. decreased contrast
increased scatter reaching the IR and decreased contrast only.
increased IR exposure and increased scatter reaching the IR only.
increased IR exposure, increased scatter reaching IR, decreased contrast.
increased IR exposure and decreased contrast only.
38
Adding a grid or increasing grid ratio results in an increase in patient dose.
False
True
39
The anode includes the
target and induction motor
envelope
target.
induction motor
40
AEC controls the ________________ of radiation reaching the image receptor.
type
quantity
energy level
all of these
41
Scatter radiation is of no value in radiographic imaging.
False
True
42
Which of the following is the formula used to determine grid ratio?
Grid ratio = height of the lead strips/distance between the lead strips.
Grid ratio = height of the lead strips/width of the lead strips.
Grid ratio = distance between the lead strips/height of the lead strips.
Grid ratio = width of the lead strips/height of the lead strips.
43
If all the convergent points were connected along the length of the grid they would form the
convergent line
focal distance
convergent point
focal range
44
If a tabletop exposure (no grid) of a humerus requires 2.5 mAs, how much mAs is needed if a 12:1 ratio grid is added?
12.5 mAs
30 mAs
0.21 mAs
0.5 mAs
45
For a lateral lumbar spine, placing a lead shield on the table behind the area of exposure
reduces the scatter exiting the patient.
reduces the scatter exiting the patient and reduces the scatter reaching IR
increases the scatter reaching the IR.
reduces the scatter reaching the IR.
46
A flat piece of lead with a hole in it that has a flange directed toward the patient is a(n)
aperture diaphragm
cone or cylinder
collimator
none of these
47
Absorption of transmitted photons by a grid caused by misalignment is
transmission reduction
grid focus
grid cutoff
grid reduction
48
The recommended SIDs that can be used with a focused grid is the
focal distance
focal range
convergent point
convergent line
49
In addition to the oil surrounding the tube, mechanical fans help to eliminate the heat produced during xray production.
True
False
50
The grid is located
just below the IR.
between the x-ray tube and the patient.
just below the x-ray tube
between the patient and IR.
51
A grid with lead strips that run parallel to each other is a
focused grid
parallel grid and nonfocused grid
nonfocused grid
parallel grid
52
The grid limits the amount of scatter radiation produced in the patient.
True
False
53
Which of the following is not a primary exposure technique factor?
SID
MA
kVp
time of exposure
54
What is the grid ratio if the grid frequency is 100 lines/inch, and the lead strips are 1.8 mm high and 0.3 mm apart?
8:1
12:1
5:1
6:1
55
the stator is made up of electromagnets
False
True
56
Higher kVp results in less absorption and more variation in the intensities exiting the patient.
True
False
57
Electromagnetic theory was developed in the late 1800s by
Maxwell.
Rutherford.
Bohr.
Planck.
58
With a rotating anode, the focal spot becomes a focal
path
stripe
circle
track
59
The main power switch is found on the
none of these
primary circut
filament circut
secondary circut
60
The motor that turns the anode operates through
mutual induction.
the use of a transformer.
self-induction
the physical connection between rotor and stator.
61
Grid cuttoff results in
all of these
may increa patient exposure
possible increased in quantum noise
reduced expose to the IR
62
The Moiré effect can be caused by
grid cassette in the bucky.
using a grid with a frequency similar to the CR laser scanning frequency.
using a focused grid upside down in the bucky.
using a grid cassette in the bucky.
63
The x-ray tube (not filaments) is found on the
filament circut
secondary circut
none of these
primary circut
64
reduces the scatter exiting the patient and reduces the scatter reaching the IR.
patient
air
table
beam
65
The unrestricted primary x-ray beam is
oval
round
square
none of the above
66
The grid is part of a device located just below the tabletop that also includes a tray to hold IR. This device is the
wafer grid
grid cassette
bucky
grid cap
67
For radiographic procedures, scatter radiation is primarily the result of
photoelectric interaction
classical interaction
compton interaction
pair production
68
The step-down transformer is found on the
primary circut
filament circut
secondary circut
none of these
69
When imaging the pelvis, changing from 14 × 17 collimation to 8 × 10 collimation requires
an increased in kVp
a decrease in kVp
an increase in mAs
a decrease in mAs
70
Using higher the grid ratio will 1. increase spatial resolu2. increase scatter clean up3. increase radiographic contrast
1, 2 and 3
1 and 3
1 and 2
2 and 3
71
An IR that has a grid permanently attached to its front surface is a
grid cassette
wafer grid
grid cap
bucky
72
The effective focal spot is smaller than the actual focal spot because the face of the anode is angled.
True
False
73
To produce x-rays, a cloud of electrons are necessary and the cathode must have a strong positive charge.
False
True
74
The device that adjusts the incoming power supplied to the x-ray circuit to maintain 220 V is the
line compensator.
timer circuit.
autotransformer.
circuit breaker
75
The formula for the grid conversion factor is
GCF = mAs without grid – mAs with grid.
GCF = mAs with grid/mAs without grid.
GCF = mAs without grid/mAs with grid.
GCF = mAs with grid – mAs without grid.
76
The purpose of the filament circuit is to
provide direct current to the x-ray tube.
produce high voltage.
reduce the current reaching the filament.
boil electrons off the filament.
77
Electromagnetic radiation
has no mass
none of these
has varying amounts of mass
has significant mass
78
The devices that change alternating to direct current are thetransformers.
rheostats
rectifiers
filaments
79
Linear grids are the most commonly used because
the tube can be angled in all directions.
they are very inexpensive.
the tube can be angled in the direction of the lead lines.
all of these
80
The volume of tissue irradiated is determined by
field size
the area of collimation
all of these
patient thickness
81
Increased collimation means: decreased field size, increased field size, less volume of tissue
decreased field size, increased field size, less vol of tissue irradiated.
decreased field size and increased field size only.
increased field size and less volume of tissue irradiated only.
decreased field size and less volume of tissue irradiated only.
82
The primary purpose of the step-down transformer is to
increase the amperage going to the filaments.
increase the voltage going to the filaments.
decrease the voltage going to the filaments.
decrease the amperage going to the filaments.
83
With digital imaging, if the mAs is too high
none of these
the image brightness will appear appropriate.
the image brightness will appear high (light).
the image brightness will appear low (dark).

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