Exam 3 Flashcards
1
Q
In a _____ CT scanner, the x-ray tube rotates continuously around the patient as the patient travels through the gantry.
A
helical/spiral
2
Q
DRR stands for
A
digitally reconstructed radiograph
3
Q
When the isocenter is marked on the patient, 3 sets of marks are created. What is the correct configuration of these marks? (where do the BBs go on the patietns body)
A
2 side marks and 1 anterior mark
4
Q
T or F: Image reconstruction occurs only after a scan is completed
A
True
5
Q
DRRs can be created from the CT scans after a process called:
A
reconstruction
6
Q
As the display field of view increases, the resulting radiation dose to the patient:
A
is not affected
7
Q
Which of the following are functions of the patient table? (2)
A
-transports the patient through the gantry
-contributes to patient safety
8
Q
Window level (WL) refers to: (2)
A
-image brightness
-the midpoint in a range of CT numbers
9
Q
The standard format used to transfer images from diagnostic imaging computers to treatment planning computers is defined by:
A
DICOM
10
Q
Image noise can be reduced by:
A
increasing mAs
11
Q
When using x, y and z coordinates to determine the tumor’s isocenter, the y coordinate indicates the isocenter’s:
A
depth
12
Q
The number for bone is:
A
1000
13
Q
The CT number for water is:
A
0
14
Q
A name for a value that represents a specific shade of gray on the CT image is:
A
CT number
15
Q
Compared to barium used for regular fluoroscopy procedures, the barium used for CT procedures is:
A
less dense
16
Q
The most common images used for radiation therapy treatment planning are acquired in what plane?
A
axial
17
Q
In which plane are CT slices originally obtained?
A
axial
18
Q
Interpolation is directly affected by:
A
pitch
19
Q
The z-axis refers to the _____ plane
A
axial
20
Q
Why are diagnostic CTs not optimal for treatment planning?
A
small bore
21
Q
The contrast given during CT simulation will highlight specific organs to further help create the treatment plan by (2)
A
- highlight the area to be treated
- highlight critical structures to be avoided
22
Q
The ability to differentiate small details in patient anatomy is referred to as:
A
spatial resolution
23
Q
In multidetector CT scanning, what determines slice thickness?
A
image reconstruction parameters
24
Q
4D treatment planning incorporates _________ in addition to regular treatment planning
A
respiratory motion
25
The mathematical unit that describes shades of gray on a CT image is:
a Hounsfield unit
26
Before the development of CT imaging, radiation therapy simulation was performed by
a conventional simulator using:
fluoroscopy
27
___ is associated with a 3D representation of tissue volume?
voxel
28
Patient MRI screening form should include: (3)
-allergies
-pregnancy
-implants, devices, objects
29
What is not a common contrast injection reaction?
dyspnea
30
During the CT simulation, the mA needs to be increased to create a change in the image quality, this will also lead to:
an increased patient dose
31
Patients at high risk of gastrointestinal perforation should be given what type of contrast medium?
Gastrografin
32
T or F: Radiopaque nonionic contrast agents are considered safe for pregnant patients
True
33
The scan field of view (SFOV) is determined by the:
CT technologist before the scan begins
34
What is the effect of increased image noise?
decreased contrast resolution
35
What is the term that describes the average level of shades of gray present on a CT image?
window level
36
Adverse reactions to iodinated contrast administration most commonly appear:
within 30 minutes of administration
37
All of the following are goals of CT simulation except to:
determine if a tumor is benign or malignant
38
Typically, a scout image for prostate CT simulation should show the:
diaphragm to mid femurs
39
The contrast most commonly used for MRI's is ____________ based.
Gadolinium-based
40
The window width (WW) determines the:
image contrast
41
What is the typical patient
positioning for a prostate
CT simulation?
supine
42
Patients taking metformin
should stop taking the
medication _____ hours after
IV contrast media injection
48
43
An advantage of a DRR
over a conventional
radiograph is that DRR
images:
can be reconstructed in multiple planes
44
Which of the following
would normally NOT be
used to administer
contrast with a power
injector?
perma-cath
45
When a traditional CT unit
is used for simulation
purposes, what change
must be made to simulate
the position of the patient
on the treatment unit?
a board must be placed on the CT table
46
Images within the therapy
department are shared
and stored through:
PACS
47
MRI interactions with
implants/devices can
result in: (3)
-malfunction
-artifacts
-displacement
48
Ancillary equipment that
must be MRI compatible
is/are: (3)
-IV poles
-stretchers
-vital monitors
49
T or F: An implanted
device that is not MRI
compatible may be
heated causing burns
True
50
To ensure that a patient's
head is not rotated during
CT simulation of the head,
the side lasers should be
centered to the:
anterior tragal notches
51
The patient should be
aligned with the _____ laser
light when performing a
CT simulation.
sagittal
52
Patient screenings for MRI
include all of the
following, except:
Physician order
53
MRI screening for
personnel should include
all of the following: (2)
-general employee info
-implants, devices, or objects
54
There are ____ MRI safety
zones
4
55
Safety line drawn around
the perimeter of the main
magnet of the MRI
scanner...is known as
The 5 Gause line
56
When a ferromagnetic
object is rapidly drawn
into the MR is known as
_____________.
missle "E"FFECT
57
For CT scanning, as mAs
increase, patient dose
______, and image noise
______.
increases;decreases
58
All of the following factors
indicate that a patient is at
increased risk of an
iodinated contrast agent
reaction except:
younger than 50 y/o
59
What part of the CT
simulator is often referred
to as the "bore"?
gantry
60
The DRR is created from:
CT
61
All of the following are
contraindications for using
contrast media
EXCEPT:
patients under 50
62
Compared with conventional (axial) CT
scanning, spiral-helical CT has:
faster imaging times
63
Spatial resolution can be
improved by using: (2)
-small detector sizes
-thin slice thickness
64
As the display field of view (DFOV) decreases:
-noise increases
-spatial resolution increases
65
The Hounsfield unit of air is:
-1000
66
The 2 most common types of contrast adminstration routes in CT simulation are:
oral & intravenous
67
If you want to adjust the brightness of your CT image, you will be adjusting the:
window level
68
The daily CT numbers test is performed using a
phantom provided by the:
CT scanner vendor
69
When a spiral-helical CT scanner takes a scout
image, the x-ray tube:
is stationary
70
Which of the following techniques would be used
for a patient who has trouble holding his or her
breath or has an irregular heartbeat?
retrospective gating
71
The CT image made directly through the
reference point corresponds to CT image
number
0
72
Which of the following
electromechanical
functions of the CT
scanner are NOT used in
simulation, yet must be
tested as part of a quality
assurance program?
gantry tilt
73
The following are true of uncontrolled areas,
except:
is monitored by the Radiation Safety Officer
74
T or F: Nuclear Regulatory Commission (NRC) was
created as an independent agency by Congress in 1974 to ensure the safe use of radioactive materials for beneficial civilian purposes while protecting people and the environment
True
75
The most common material used for protective barriers is:
concrete
76
T or F: Diodes are preferred to use for beam calibration.
False
77
T or F: American Association of Physicists in Medicine (AAPM) is advancing medicine through excellence in the science, education and professional practice of all physics; a broad-based scientific and professional
discipline which encompasses physical principles with applications in biology and medicine.
False; it's medical physics
78
Correction factors that may be applied to ionization chambers are as follows: (3)
-temperature
-volume
-pressure
(cause ionization)
79
T or F: The National Council on Radiation Protection and
Measurements (NCRP) seeks to formulate and widely disseminate information, guidance and recommendations on radiation protection and measurements which represent the consensus
of leading scientific thinking.
True
80
OSL crystals are excited
by:
Light
81
TLD's store the information for:
weeks
82
OSL's are made of:
Aluminum Oxide (Al2O3)
83
T of F: Diodes provide real-time readings
True
84
Gas-filled detectors include all of the following, except:
Scintillation detectors
85
Proportional counters are typically used for ___________.
Neutrons
86
TLD's are accurate within +/-______%
5
87
Materials used for primary barriers include all the following except:
cerrobend
88
T or F: Primary Barrier is directly hit by the useful
radiation beam
True
89
OSL's store information for
Year
90
TLD's crystals light up when exposed to:
heat
91
T or F: Geiger Mueller Counters measure the amount of radiation
False
92
At the completion of a prostate seed implant, the
room is surveyed using a ____________.
geiger mueller counter
93
Radiation area:
>/= ___rem
In ___ (time)
At ___ cm
person can receive greater than or
equal to 0.005 rem (.05 mSv or 5 mrem) in 1 hour @ 30
cm from the source
94
High radiation area:
>/= ___ rem
___ (time)
At ___ (cm)
posted when a person can receive greater than or
equal to 0.1 rem (1 mSv) in 1 hour @ 30 cm from the
soucre
95
Very high radiation area:
> ___ rad
In ___ (time)
At ___ (Meters)
posted when a person can receive more than 500
rads(5 cGy) in 1 hour @ 1 meter from the source
96
Caution: Radioactive
materials
posted in areas where sources of radiation are used
and/or stored
97
Shielding for neutron contamination must be
considered at energies of ____________.
> 10 MV
98
T or F: Signage for radiation areas include a
radiation symbol with 3 blades that are marroon
or black on a yellow background.
Flase
99
Medicare and medicaid require the following
accreditation from the following:
-The Joint Commission (TJC)
-American College of Radiology (ACR)
-American College of Radiation Oncology (ACRO)
100
Average concrete thickness for secondary
barrier = _______ for beams with energies of 15 - 18
MV.
1 meter
101
MRI zone 1:
- Safest
- Pulic can acess freely
- No hazards by magnet
102
MRI zone 2:
- Buffer (between 1 and 3)
- Patient acess with supervision
- Generally no hazards from magnet
103
MRI zone 3:
- Restricted with physical barrier
- Only patients who did interview can acess with supervision
104
MRI zone 4:
- Magnet room, only acessable by passing zone 3
105
5 gausse and below is considered ___ for public
safe
106
Above what gausse line can interfere with implated devices
5
107
MRI screening includes (3)
- Printed form
- Review of printed screening form
- Verbal inteview
108
GFR can happen in patients ___ years or older
60
109
General patient related information during MRI screening include (4)
- age
- height
- weight
- sex
110
What is occupational rad dose
1rem/1year
111
Public rad dose is
- yearl
- weakly
- 0.5rem/1year
- 0.1/weekly
112
energies above ___mV need shielding for possible ___ contamination
- 10mv
-neutron
113
Materials used for barriers include (4)
- lead
- tugnsten
- aluminium
- concrete (most common)
114
Primary concrete barries is ___ meters
2
115
Primary barrier is hit by ___ beam while secondary barrier is hit by ___
- Primary
- Scatter
116
Mazeless vaults characteristics (2)
- least square footage
- Thicker walls
117
Mini maze characteristics
- reduced square footage and shielding requirements
118
Maze vault characteristics
- Blance of square footage and shielding
119
Ionization chamber meters measrue:
Electrical signal
120
Ionization chamber meters are accurate within ___% +/-
2%
121
Cutie pies are
portable ion chambers
122
What is used to calibrate external beam radiation machines?
Farmers chamber
123
Geiger-muller detector detects
low levels of radiation and contamination
124
Diodes give ___ time readings
real
125
Neutron detectors used in ___ and ___ therapy greater than ___mV
- proton
- photon
- 10 mV
126
proprotional counters typically used in ___ dosimetery
Photon
