fluoro test physics Flashcards
(125 cards)
1
Q
introduced in the 1950’s
brightened image
eliminated need to dark adapt
improved detail
A
image intensification
2
Q
allows a means to indirectly view image
greatly reduced dose to fluoroscopist
A
image intensification
3
Q
what is the fluoro imaging chain
A
x ray tube
image intensifier
recording system
viewing system
4
Q
entire tube is approximately ____ in length
A
50 cm
5
Q
entire tube is approximately ___ in diameter
A
15-58 cm
6
Q
5 main parts of image intensifer
A
input phosphor
photocathode
electrostatic focusing lenses
accelerating anode
output phosphor
7
Q
what is the input phosphor made of
A
cesium iodide
8
Q
what is bonded to the curved surface of the tube
A
input phosphor
9
Q
what is typically 15-30 cm in diameter
A
input phosphor
10
Q
cesium iodide absorbs exit radiation and emits LIGHT in response
A
input phosphor
11
Q
made of cesium and antimony compounds
A
photocathode
12
Q
the metals emit electrons in response to light stimulus
A
photocathode
13
Q
what is bonded directly to input phosphor
A
photocathode
14
Q
negatively charged plates placed along the length of the image intensifier
these negatively charged plates repel the electron stream focusing it onto the small output phosphor
A
electrostatic focusing lenses
15
Q
what puts the electron stream in motion at a constant velocity
A
accelerating anode
16
Q
the accelerating anode has a constant potential of what
A
25 KV
17
Q
made of zinc cadmium sulfide
A
output phosphor
18
Q
is the output phosphor bigger than the input
A
no, it’s much smaller
19
Q
absorbs electrons and emits lights in response
A
output phosphor
20
Q
what has the diameter of 2.5 cm
A
output phosphor
21
Q
Ability of an image intensifier tube to convert extra energy into light energy, and increase the brightness of the image in the process
A
brightness gain, or conversion factor
22
Q
formula for brightness gain
A
bg = flux gain x minification gain
23
Q
Expressed as a ratio of the number of light photons at the output phosphor to the number of light photons admitted in the input phosphor
A
flux gain
24
Q
What representatives conversion efficiency?
A
Flux gain
25
The degree to which the image is minified from input phosphor to output phosphor
minification gain
26
formula for minification gain
minification gain = input phosphor diameter squared divided by output phosphor diameter squared
27
what is measured in candela per square meter per milliroentgen per second
Conversion factor
2 c’s= candles
28
What is roughly equal to one percent of the brightness gain value?
conversion factor
29
Function of the fluoro unit that maintains the overall appearance of the image, and automatically adjust the KVP and MA
ABC
30
How does ABC work?
by monitoring the current through the image, intensifier or the output phosphor intensity, and adjusting to keep the preset values
we see lag
31
during this the voltage to the electrostatic lenses is increased causing them to become more negative
this increase tightens the diameter of the electron stream and focal point is shifter farther away from output phosphor
mag mode
32
numbers in multi field mode
30/23/15 cm
33
mf does what two things
improved spat res and increased patient dose
34
what is spat res measures in
line pairs per mm (Lp/mm)
35
fluoro line pairs per mm
4-6
36
when, in this mode, the voltage to the electrostatic lenses is increased this increase tightens the diameter of the electron stream, shifting it further away from the output phosphor. Only the electrons from the center area of the input phosphor interact with the output phosphor, which makes it look magnified.
mag mode
37
Static imaging process in which a cassette is used to obtain an image
Cassette spot film
38
What causes a much higher radiation dose, because images are obtained in radiographic mode
Cassette spot film
39
What uses a roll of film?
Film cameras, or Photospot cameras
40
What is used for video or cookie swallows
Video recorder
41
What are the two devices that can connect the image intensifier to the monitor?
Camera tube and charged coupling device
42
Connect the image intensifier to a television monitor most often used in the Vidicon tube a diode tube contained in a glass envelope to maintain a vacuum cathode has an electric gun
camera tube
43
Three types of viewing systems
Television monitor, liquid, crystal display, monitor and plasma monitor
44
XLELM
remnant beam to light
light to electrons
electrons to light
45
entire tube length
50 cm
46
fluoro imaging chain
tube
II
recording system
viewing system
47
tube diameter
15-58 cm
48
what is made of zinc cadmium sulfide
output phosphor
49
X IN XLELM
eXit radiation is received by input phosphor. the cesium iodide in the input phosphor emits light in response
50
L IN XLELM
Light hits the photocathode and it emits electrons
51
E IN XLELM
electrons lol
52
second L in xlelm
electrons are absorbed by the zinc cadmium sulfide in output phosphor and emits light
53
M in xlelm
monitor
54
5 main parts of II
input phosphor
photocathode
electrostatic focusing lenses
output phosphor
55
made of cesium iodide
input phosphor
56
does the input phosphor face patient
yes
57
II diameter
15-30 cm
58
made of cesium and antimony components
photocathode
59
bonded directly to input phosphor
photocathode
60
metals emit electrons in response to light stimulus
photocathode
61
negatively charged plates placed along the length of the II
focusing lenses
62
puts the electron stream in motion at constant velocity
accelerating anode
63
what is located at the neck of the II
accelerating anode
64
what a constant potential of 25 kv
accelerating anode
65
what has a diameter of 2.5 cm
output phosphor
66
function that maintains overall brightness of
image
ABC
67
fluoro lines per mm
4-6
68
when in mag mode what is increased
voltage to lenses
69
what does the increase in voltage do during mag mode
tight es the diameter of electron stream
70
tri focus image intensifier numbers
30/23/15
71
multi field mode formula
mf = full size input diameter divided by selected input diameter
72
does multi field mode improve spat res
yes
73
does multifield
mode decrease pt dose
no it increases
think of it being more focused on the patient so more dose
idfk
74
3 kinds of recording systems
cassette spot films
film cams / photospot
video recorders
75
fluoro mode ma
2-5
76
radiographic mode ma
100-1200
77
static imaging process in which a cassette is used to obtain image
cassette spot film
78
why do cassette spot films acquire a higher radiation dose
image are required in radiographic mode which is a higher ma
79
what recording system used a roll of film and how long is it
film cameras and 105 mm
80
do film camera require double or half the dose as cassette spot filming
half
81
what are the two devices that can connect the II to the monitor
camera tube
CCD
82
what is most often used in vidicon tube
camera tube
83
does the cathode have an electric gun in a camera tube
yes
84
what connecting device has a series of focusing coils which accelerate and controls electron beam
camera tube
85
what device has a series of metal oxide semiconductors
ccd
86
what device when hit with light generates an electrical charge and stored said charge in a capacitor
ccd
87
is ccd or camera tube better
ccd
88
3 types of viewing system
tv monitor
liquid crystal
plasma monitor
89
purpose of this is to convert electrical signal from camera tube or ccd back to a visible image
tv monitor
90
beam sweeps the screen in a raster. pattern
tv monitor
91
high resolution monitors have a ____ line system
1024
92
tv monitor lp/mm display
1-2
93
what is the weak link of viewing systems
tv monitor
94
what is made of several layers
lcd monitor
95
whay has layers that are in a naturally twisted state
lcd
96
# of tfts =
# of pixels
97
what has more brightness / resolution that tv monitors
lcd monitors
98
what happens when current hits crystal layer
it untwists
99
similar to LCDS but have a think layer of pixels
plasma monitor
100
what emits red green and blue light
plasma monitors
101
what can produce billions of shares of color
plasma monitor
102
does CCD increase spat res
yes
103
what does the CCD replace
camera tube
104
what replaces the II in recent fluoro advances
flat panel detector
105
cesium iodide amorphous silicon
indirect capture
More I’s
106
amorphous selenium
direct
107
2 types of flat panel capture
indirect and direct capture
108
advantages of flat panel detectors
less bulk
easy to manipulate
greater access to the patient
109
flat panel detector spat res
2.5 - 3.2
110
what provides a 50% reduction in patient dose
flat panel detector
111
air kerma should not exceed
1/min or 88mgy / min
112
Exposure in the air with a computation to estimate absorbed dose to patient
DAP
113
Same as DAP and it’s a total total air karma plus the area of the beam at the entrance of the patient
KAP
114
the collimator shutters should restrict the beam to the input phosphor within
+/-3%
115
beam should aligned to the center of the image intensifier within _____ of SID
+/-2%
116
System averages multiple image frames together this reduces image noise, and therefore less radiation is needed to maintain image quality
Frame averaging
117
what is used when a radiologist takes an image of a stomach and then decides he just wants an image of it he duodenal bulb and then he can just shutter the image instead of having to take another
last image hold
118
Automatically controls the output of the x-ray unit to maintain a constant exposure to the image intensifier
automatic exposure rate control
119
What is connected to the output, phosphor of the Imogen, intensifier by a fiber, optic bundle or optical lens system diode contained in a glass envelope to maintain a vacuum electron gun that provides a continuous stream of electrons control, grid and coil, accelerate and control the electron beam
camera tube
120
flux gain formula
number of output light photons
divide
number of input x ray photons
121
thinned segment of the glass envelope positioned closest to the output phosphor
face plate
122
allows transmission of light from the II to the camera tube
face plate
123
bonded to the face plate and is a thin layer of graphite material that conducts electricity
signal plate
124
thin enough to transmit light traveling through the face plate from the II but thick enough to conduct electricity that will be generated in the camera tube
signal plate
125
photoconductive layer made it antimony trisulfide. will conduct electricity if illuminated otherwise it acts as an insulator
target layer
