Fluoroscopy Syllabus Flashcards
1
Q
Irradiation of the bone marrow results in hematological depression. Which cell type is most severely depressed?
A
lymphocytes
2
Q
What are examples of high bone marrow dose examinations?
A
barium enema
upper GI series
abdominal angiography
3
Q
What are examples of somatic indicators?
A
- bone marrow
2. thyroid and skin
4
Q
What are somatic effects?
A
damage to the individual being irradiated (vs. genetic effects which affect future offspring)
5
Q
Examinations on the order of ___ rads to the gonads may produce temporary sterility.
A
30 rads
6
Q
What does the nonthreshold, linear dose-effect curve hypothesis suggest?
A
any dose of radiation, no matter how small, is considered to have some degree of effect
7
Q
Regulatory radiation guides are based on what?
A
nonthreshold dose-effect relationship
8
Q
What does the Law of Bergonie and Tribondeau state?
A
the radiosensitivity oftissues depends on the # of undifferentiated cells, the degree of mitotic activity, and the length of time the cells of the tissue stay in active proliferation
9
Q
What tissue types are the most radiosensitive?
A
blood forming organs (spleen, red bone marrow)
GI tissue
developing embryo/fetus (in the 1st trimester)
10
Q
What cell types are the most radiosensitive?
A
(MOST SENSITIVE to LEAST sensitive)
lymphyocytes or WBC > erythrocytes or RBC> epithelial cells > endothelial cells > connective tissue cells> bone cells > nerve cells > brain cells > muscle cells
11
Q
What are the most frequently occuring radiation-induced cancers/
A
(in descending order of susceptibility)
female breast > thyroid gland > hematopoietic tissue > lungs > GI tract > bones
12
Q
Absorbed doses of about ___ rads to the fetus could result in a spontaneous abortion.
A
50 rads
13
Q
Deleterious effects may be produced with doses of as little as ___ rads delivered to the embryo.
A
10 rads
14
Q
Lead goggles of at least 0.25mm Pb equivalence reduce radiation exposure to the eyes by what %?
A
85-90%
15
Q
What are stochastic effects?
A
the probability of an event occurring, rather than its severity
Ex. somatic effects or carcinogenesis
16
Q
What are non-stochastic effects?
A
those effects for which the severity of an effect varies with radiation dose
Ex. cataracts, bone marrow cell depletion
17
Q
If the operator is wearing protective clothing, substantial exposure reduction from ____ type of radiation can be achieved.
A
scatter radiation
18
Q
What does “whole body dose” refer to?
A
exposure to any of the following:
- head
- trunk
- arms above the elbow
- legs above the knee
19
Q
What is the annual maximum whole body dose for occupationally exposed persons?
A
5 rem (or 0.05 Sv)
20
Q
What is the annual maximum occupational dose equivalent for skin and extremities for occupationally exposed persons?
A
50 rem or 0.5 Sv
21
Q
What is the annual maximum occupational dose equivalent for lens of the eye for occupationally exposed persons?
A
15 rem or 0.15 Sv
22
Q
What is the radiation dose limit for individual members of the public ?
A
0.1 rems (1mSv) in a year
OR 0.002 rem *or 2 millirems) in any one hour
23
Q
How often should film badges or TLD badges be changed?
A
once every month (*not specified by regulations though)
24
Q
What type of light receptor is responsible for daylight (photopic vision)?
A
cones
25
What type of light receptor is responsible for nightime (scotopic vision)?
rods
26
What is nightime vision called?
scotopic vision
| rods perceive this
27
What is daytime vision called?
photopic
| cones perceive this
28
What light receptors perceive color?
cones
| *rods perceive grays
29
What is the ability to perceive fine detail called?
visual acuity
30
Which light receptors have greater visual acuity?
Photopic visual acuity (cones) is about 10x greater than scotopic acuity
31
How do you improve visual acuity?
bring the illumination of the image into the cone vision region (which is in the center of the retina) to obtain high brightness
32
What is the normal viewing distance of an image?
12 to 15 inches
33
What is the time required by the eye for recognition of an image (integration time)?
0.2 second
34
What is the unit for ABSORBED dose?
rad (or gray- SI unit)
| *stands for radiation absorbed dose
35
What is the unit for dose equivalent?
rem (sievert- SI unit)
36
What is the conversion between Sv and rem?
1 Sv= 100 rem
37
What are the 3 basic principles to reduce dose to radiation?
time, distance and shielding
38
What is the target-to-tabletop distance on fluoroscopes?
at least 18 inches
39
how does intensity vary with distance?
intensity varies inversely with the square of the distance
| (I1)(D1)^2= (I2)(D2)^2
40
If the distance from an x-ray source is tripled, the intensity is reduced by how much?
1/9
41
If the distance from an x-ray source is halved, how does this affect intensity?
exposure intensity is quadrupled
42
What is the half-value layer (HVL)?
defined as the thickness or layer of a specified materrial which attenuates the x-ray beam to an extent that the exposure is reduced to one-half
(HVL is used to describe the quality of an x-ray beam)
43
What does a higher HVL mean for an x-ray beam?
a higher HVL for an x-ray beam means that it has higherr penetrability (it can penetrate a given thickness of material to a greater extent than a lower HVL layer)
44
What is the maximum dose equivalent to an embryo/fetus during the ENTIRE pregnancy due to occupational exposure of a declared pregnant woman?
cannot exceed 0.5 rem (5 mSv)
45
What is the maximum dose equivalent to an embryo/fetus during ANY month of the pregnancy ?
may not exceed 0.05 rem (50 mrems)
46
The gonad shield protects the gonads from exposure to the _____ beam.
PRIMARY x-ray beam
47
which type of gonad shield is best suited for fluoroscopic exams?
```
shadow shield
(not flat, contact shield of shaped/contoured contact shield)
```
48
What does the state of CA regulations require for minimum lead equivalent of gonadal shielding?
0.5mm
| as opposed to 0.25mm
49
What is the target to panel (tabletop) distance?
at least 12 inches for under table x-ray tubes
50
Which fluoroscopic equipment quality control tests should be performed daily?
1. brightness/contrast optimization of monitor
2. verification of protective devices
3. fluoroscopic tower locks
4. compression device/spoon observation
5. automatic collimation**
6. low contrast performance
7, KvP and ma **
8. mobile space for c-arm fluoroscopes**
51
Which fluoroscopic equipment quality control tests should be performed semi-annually?
1. shutters ***
2. automatic brightness control (ABC) tracking ***
3. gain control system
4. high contrast resolution (sensitivity)
5. low contrast resolution (detectability)
6. five minute timer
7. actual fluoroscopic beam size
8. filtration
9. minimum source-to-tabletop distance
10. KVP
11. typical patient exposure rates
12. maximum exposure rates
13. apron/glove integrity
14. distortion
52
what is the main source of scatter radiation during fluoroscopic exam?
the patient
53
What is the best configuration for minimizing radiation exposure to the patient and operator?
x-ray tube UNDER the table
54
For an x-ray tube located UNDER the table, the maximum intensities are received below the tabletop at what angles?
angles 120 and 135 degrees from the primary beam
55
For an x-ray tube located OVER the table, the maximum intensities are received below the tabletop at what angles?
30 deg
56
Minimum intensities are received at scatter angles in what order?
45, 60, and 90 deg to the primary beam
57
which xray exam has the most somatic detriment or carcinogenic potential in males and females?
barium enema exam
| *upper GI is second most in males *lumbosacral films are next for females
58
What are the 4 different types of cameras that are in use?
1. vidicon
2. plumbicon
3. image-orthicon cameras
4. charge-coupled device
59
what are the two typical ways to record dynamic (motion) images ?
1. video tape recording
| 2. cinefluorography
60
What are the 2 advantages of video tape recording compared to cinefluorography?
1. image is available for iNSTANT REPLAY without any intermediate processing system
2. patient's exposure to radiation is NOT increased
61
What are the 2 disadvantages of video tape recording compared to cinefluorography?
1. poor image quality
| 2. fixed frame speed (30 frames /sec)
62
What are the disadvantages of cinefluorography compared to video tape recording?
increased patient radiation dose
63
What is this: the operation of camera shutters at the same frequency as x-ray pulses (radiation production)?
synchronization
64
Why is synchronization important?
means that the patient is exposed to pulse xrays only when the camera shutters are open
65
How is framing frequency calculated?
```
# frames of film per second (f/s)
*is a division of 60 (8.5, 15, 30, 90, 120)
```
66
How does patient radiation dose related to framing frequency?
(directly proportional)
| Higher framing frequency means higher radiation dose
67
What is : the speed of any given camera system depends on the ability of its lens to concentrate light on a given area and is denoted by ?
f-number
68
How do you calculate f-number?
focal length / lens diameter
| *usually in mm
69
What does a low f-number indicate?
faster lens
70
What is this: refers to the use of the available film to control the image as seen from the output phosphor?
framing
71
What kind of framing is this? The diameter of teh circular image from the optical system is larger than the shortest dimension of the film?
overframing
72
What kind of framing is this? The diameter of the circular image from the optical system is equal to the diagonal measurement of the rectangular aperture?
total overframing
73
What kind of framing is this? The diameter of the intensifier image at the output phosphor and the smallest dimension of the cine frame are the same.
exact framing
74
What kind of framing is this? The max. size of the fluoroscopic image is smaller than the smallest dimension of the frame?
underframing
75
The radiation dose at the tabletop for cinefluorography is approximately how many times greater than the radiation dose for routine fluoroscopy?
10x greaterr
76
What are the 4 methods of static image recording?
1. video disc recording
2. spot-film camera
3. conventional cassettes
4. digital fluorography
77
What % of the U.S. population is fluoroscoped each year?
5%
78
Which fluoroscopic examinations (by body area) is the most common?
1. GI tract- 53%
2. barium enema- 28%
3. other exams- 19%
79
Bucky slot cover must be covered with how many mm of lead equivalent material?
0.25mm
80
During fluoroscopy, where is the bucky tray moved to?
the end of the examination table, leaving an opening in the side of the table about 2 inch wide at the fluoroscopist's gonad level (which must be covered with at least 0.25mm Pb lequivalent material)
81
Scatter radiation from the patient at ONE FOOT from the patient could be as high as what?
500 millirads per hour
82
How is total brightness gained in the image intensifier measured?
minification game x flux gain
83
Describe the parts and function/flow of xrays entering the image intensifier (II) .
Xrays from the patient strike the II's INPUT PHOSPHOR which absorb the xrays and converts their energy into light photons. The photons are immediately absorbed by the PHOTOCATHODE causing electrons to be given off , which are accelerated by the ACCELERATING ANODE and focused with little distortion by ELECTROSTATIC LENSES onto a smaller fluorsecent layer of material called the OUTPUT phosphor. The output phosphor absorbs electrons and emits light photons, which are then available for viewing.
84
What image quality consideration is this when statistical fluctuation occurs when the number of absorbed photons is low and manifests itself in the fluoroscopic image as a grainy or blotchy appearance?
quantum mottle
85
The visibility of quantum mottle is determined by which factors?
resolution
sensitivity
contrast
86
How can quantum mottle level be adjusted?
changing exposure factors (kVP and mA)
87
Which image quality consideration is measured in line pairs per millimeter?
resolution
88
What is resolution?
the ability of the imaging system to differentiate small objects as separate images when they are close together
89
The overall resolution of an imaging system is expressed in terms of what?
modulation transfer function (MTF)
90
A fall-off in brightness at the periphery of an image or image brightness loss at the edges of the image is called what?
vignetting
91
What is the blurring of the image as the camera is moved rapidly during an imaging procedure called?
lag effect
92
Size distortion is mainly caused by what?
object-to-image distance (OID)
93
What causes shape distortion?
geometric problems in the shape of the image intensification tube; may result in pincushion distortion
94
Resolution is measured how?
in line pairs per millimeter (lp/mm)
95
Pincushion distortion is a type of what?
SHAPE distortion (not size distortion)
96
Which component of the image intensifier changes the field of view from standard to magnification mode ?
electrostatic lens
97
in magnification mode, image intensifier resolution can be increased from ___ to ___?
increased from 4 to 6 lp/mm
98
What are the 3 components of closed-circuit television systems?
1. camera
2. camera control unit
3. monitor
99
What does it mean to be a closed-circuit system?
video signal is transmitted from one component to the next through cables (instead of air)
100
Are fluoroscopic television systems an example of open or closed-circuit system?
closed-circuit
| An example of open circuit is broadcast television
101
What is the most common type of camera used in fluoroscopy?
vidicon
102
How many lines per image are typical of an image produced by most fluorosocpy and commercial television systems?
525 lines
| *the total number of lines in the entire picture does NOT change even if the size of the television screen changes
103
What does the camera control unit do?
contains the power supply and all the controls that regulate the camera; it amplifies the video signal, regulates the focusing, and synchronizes video signal between the camera and monitor
104
Which component of closed-circuit television system regulates the brightness and contrast?
monitor
105
What does the monitor do?
contains the cathode-ray-tube (CRT) and regulates brightness and contrast
106
why is it necessary to synchronize or coordinate the video signal between the camera and the monitor?
to avoid unnecessary flicker in the television picture
107
What is synchronization? why is it necessary?
operation of camera shutters at the same frequency as x-ray pulses; this is to make sure that there is no exposure made while the cine film is being transported from frame to frame
108
What is the normal framing frequency?
it is the # of films per second (f/s)
| usually is a division of 60 (7.5, 15, 30, 60, 90, 120)
109
What effect does a higher frame rate have on patient dose?
higher frame rate sequence equals higher patient dose during the examination
110
What is the F-numberr?
the ability of the lens of a camera system to concentrate light on a given area of the cine film (determines SPEED!)
111
What does a higher F-number suggest?
less light is available to form the image on the cine film
112
Manufacturers report what % reduction when utilizing video disc recording during fluoroscopy?
up to 95% dose reduction
113
What is video disc recording? Why is this technique advantageous?
It is AKA electronic radiography. It combines instantaneous image of fluoroscopy coupled with short exposure time associated with a radiograph. It permits fluoroscopic radiation to continue only long enough to build up a useful image on the display monitor. The image is stored as a single frame on the video disc recorder.
114
What are examples of contrast media?
barrium
iodine
*they are low toxicity, possess high atomic numberrs
115
Image contrast is largely dependent upon what?
tissue density (affects attenuation and absorption)
116
Higher atomic numbers such as contrast agents (iodine and barium) and calcium (in bones) absorb more OR less xrays than the surrounding tissues?
higher atomic number materials absorb more xrays
117
What is the minimum source-to-skin distance for MOBILE fluoroscopic equipment vs. STATIONARY equipment?
mobile: minimum source-to-skin is 12 inches (30cm)
stationary: is 18 inches (45 cm)
118
At what tube current does fluoroscopic examinations operate at?
<5 mA
| compared to 100 to 500mA for radiography
119
Which component of the image intensifier focuses the electrons?
electrostatic lenses
120
Which component of the image intensifier converts x-ray photons into electrons?
input phosphor
121
Which component of the image intensifier converts the energy of electrons into visible light?
output phosphor
122
How is minification gain calculated?
(input screen diameter)^2/ (output screen diameter)^2
123
Does minification gain improve the quality of an image?
no.
it is simply an increase in brightness or intensity. It does not change the # of xray photons making up the image either.
124
Most modern image intensifiers are constructed with what size output phosphor?
1 inch output phosphor
125
what is flux gain?
measurement of the increase in light photons due to the conversion efficiency of the output screen
126
What is minification gain?
occurs as a result of the same number of electrons that were produced at the large input phosphor being compressed into the area of the small output phosphor; its the ratio between the two
127
By what percentage can brightness gain deteriorate annually?
as much as 10% per year due to the aging of input and output screen phosphors
128
What is the conversion factor used for?
measures brightness gain while taking into account the 10% deterioration annually
129
How is the conversion factor calculated?
intensity of output phosphor (measured in candelas) / (millirads/second)
130
Does a small (6in.) or large (9 in.) image intensifier provide better quality images?
small image intensifier (bc the center of the image intensifier has the best resolution and less geometric distortion)
131
How is the ratio of patient radiation dose calculated in magnification mode compared to normal mode ?
(normal mode size) ^2/ (mag mode size)^2= increase in patient radiation dose
132
When operating the II in the magnified 6 inch mode from the normal 9 inch mode, the patient will receive how many times more radiation dose?
9^2/ 6^2= 81/36= 2.25x the radiation dose
133
Image quality of the image intensifier system is affected by what?
1. quantum mottle (aka scintillation)
2. contrast
3. resolution
4. distortion
134
What factors diminish contrast?
1. contrast diminishes as the II ages
2. retrograde light flow from the output phosphor
3. input phosphor doesn't aborb all the photons
135
What is the relationship between object size and resolution?
INVERSELY related
| as the object size becomes smaller, it has better resolution; and the spatial frequency becomes higher
136
What is a "perfect" MTF?
MTF of 1 at all frequencies
137
Why does pincushion distortion result? (it is a warped image which bends straight lines inwards)
consequence of projecting the image formed on a curved input phosphor to a flat output phosphor
138
why does veiling glare occur?
consequence of light scatter in the output window of the image intensifier
139
what affect does veiling glare have on the contrast of an image?
reduces the contrast
140
How does kVP affect image contrast?
image contrast degrades as kVP is increased
141
What is the maximum tabletop dose rate when imaging with high level "boost" fluoroscopy?
20 rads/min
142
What is the gonadal dose to a female patient during a barium enema exam?
790 millirads
143
Scattered radiation exposure at 3 feet from the patient could be as high as:
50 mR/hr
144
Scattered radiation exposure at 2 feet from the patient could be as high as:
100 mR/hr
145
Scattered radiation exposure at 1 feet from the patient could be as high as:
500 mR/hr
146
What is the minimum required thickness (lead equivalent) of a primary protective barrier for systems operating above 125 kilovolt peak (kVp)?
2mm lead equivalent
147
What is the maximum exposure rate allowed for fluoroscopic equipment manufactured after August 1, 1974, WITHOUT automatic exposure controls (AEC)? what about WITH AEC?
5 rads/ minute (w/o AEC)
| 10 rads/min (w/ AEC)
148
The tabletop intensity of the X-ray beam for a system operating at 80 kVp should not exceed how many rads per minute?
2.2 rads/ minute
The maximum x-ray beam intensity allowed is 10 rads/minute, however, the recommendation is that it should not exceed 2.2 rads/minute for each mA of current at 80 kVp.
149
If the Bucky tray is moved to the end of the examination table, leaving an opening at the gonadal level, this must be automatically covered with at least:
0.25mm lead equivalent
150
What happens to a patient's entrance skin exposure (ESE) when the field of view is decreased on the image intensifier?
increases
(because Decreasing the field of view on an image intensifier is the principle behind magnification mode. As the voltage is increased to the electrostatic lens, a smaller beam of electrons is sent to the output phosphor with a resulting decrease in minification gain and image brightness. This results in a dimmer image, requiring increased exposure rates, and an increase in patient dose. Syllabus pg 19-20.)
151
What is the most commonly used video frame rate?
30 frames/ second
152
Which imaging method can reduce patient exposure by taking short x-rays with low frame rates?
pulsed fluoroscopy
153
The purpose of the Radiation Control for Health and Safety Act of 1968 was to:
The Radiation Control for Health and Safety Act of 1968 was aimed at minimizing patient and operator x-ray exposure, without sacrificing diagnostic diagnostic information.
154
What is the typical milliampere (mA) usage during spot filming?
Spot films are images taken during an examination using much higher mA setting, typically over 100.
155
Film badge readings are recorded using what unit of measurement?
Sievert
156
Which type of contrast is reduced by increasing the kilovolt peak (kVp)?
subject contrast
157
What is "detector contrast" determined by?
characteristics of the II, the type of TV camera target, amplitude of the output image brightness/video signal, and the brightness/contrast settings of the monitor to optimize the signal-to-noise ratio
158
For routine fluoroscopy, what is the maximum tabletop x-ray exposure?
5 rads/ minute
159
What components make up the target assembly of a television camera tube?
1. glass face place
2. signal plate
3. target
160
What is the approximate radiation exposure from a routine upper gastrointestinal (GI) study?
6 rads
A 2-minute upper G.I. tract fluoroscopic study could deliver a skin entrance exposure to the patient as much as 5-15 rads.
161
what percentage of the active bone marrow of the body does a lead apron cover?
80%
Lead aprons cover about 80% of the active bone marrow of the body. The bone marrow outside the apron is contained primarily in the skull, the arms, and clavicles.
162
What approximate dose causes acute skin erythema?
200-300 rads (200-300 centigray)
| Doses exceeding several hundred rads (1 rad = 1 centigray) can cause acute skin erythema. Syllabus pg 35.
163
Aprons of at least 0.25 mm lead equivalent must be worn if the operator is likely to receive at least what dose of radiation?
5 millirads/hr
164
Which type of camera is designed for use in the cardiac catheterization lab?
```
plumbicon camera
(also charge-coupled device)
```
165
What is the disadvantage to plumbicon cameras?
quantum mottle (grainy appearance)
166
What are the advantages of charge-couple devices?
- smaller in size
- lower in power consumption
- lower in price
- has a longer life
167
What is the estimated reduction in exposure from diagnostic x-rays that can be achieved without compromising patient benefit?
50%
168
As detector element (DEL) size decrease, what happens to spatial resolution and pitch?
spatial resolution increases (inversely related to DEL)
pitch decreases (directly related to DEL)
Pitch is the distance between two adjacent DELs. As DEL size decreases, pitch also decreases.
169
What is the approximate dose to the fetus from an upper-GI examination of a pregnant patient with a total skin exposure of 5 Roentgens?
100 millirads
1 Roentgen = 1 Rad. 1 Rad = 1,000 millirads. 5 Roentgens of skin exposure is equal to 5,000 millirads. The dose to the fetus is approximately 2% of the skin dose. 2% of 5,000 = 0.02 * 5,000 = 100.
170
Grids are used in x-ray systems to improve image quality, but can increase the radiation dose to patients and staff by how much?
1.5 to 2x
171
Which of the following milliamperages (mA) would be used during spot filming?
100 mAs
| Spot films use high x-ray currents (>100mA) and short exposure times to generate useful images. Syllabus pg 33.
172
What is the maximum allowed tabletop x-ray exposure rate when performing fluoroscopy?
10 rads/min
The maximum x-ray beam intensity allowed is 10 rads/minute, however, the recommendation is that it should not exceed 2.2 rads/minute for each mA of current at 80 kVp.
173
What happens to a patient's entrance skin exposure (ESE) when the field of view is decreased on the image intensifier?
INCREASES.
Decreasing the field of view on an image intensifier is the principle behind magnification mode. As the voltage is increased to the electrostatic lens, a smaller beam of electrons is sent to the output phosphor with a resulting decrease in minification gain and image brightness. This results in a dimmer image, requiring increased exposure rates, and an increase in patient dose. Syllabus pg 19-20.
174
The purpose of the Radiation Control for Health and Safety Act of 1968 was to:
minimize operator and patient exposure
The Radiation Control for Health and Safety Act of 1968 was aimed at minimizing patient and operator x-ray exposure, without sacrificing diagnostic diagnostic information.
175
What fluoroscopic mobile control test should be performed weekly?
mA and kVP with phantom if it has an ABC
176
how long do maintenance records have to be kept?
3 years
177
how long should protective, corrective, cleaning and chemistry replacement records be kept ?
1 year
