Chapter 33: Fluoroscopy Flashcards
1
Q
Dynamic movement of an image?
A
Fluoro
2
Q
KUB is considered what type of image?
A
static image
3
Q
Active diagnosis in fluoro is in control of who?
A
domain of radiologist
4
Q
What can the radiologist see when doing fluoro?
A
Visibly watching barium go through the esophagus to the stomach
4
Q
who was the fluoroscope invented by and when?
A
Invented by Thomas Edison in 1896
5
Q
When Thomas Edison invented fluoro how were the machines back then?
A
Consisted of x-ray tube and hand-held fluoroscopic screen that was very high exposure directly into eyes, neck and hands
6
Q
Who was the first person to introduce radiation protection and was also a dentist?
A
William Rollins
7
Q
Where is the x-ray tube and image intensifier located in fluoro?
A
x-ray tube is below and image intensifier is on top
8
Q
dynamic imaging modality designed to observe moving structures in the body
A
Fluoroscopy
9
Q
When was the image intensification (ii) developed?
A
in 1948
10
Q
Fluoro is considered what two types?
A
CR in the OR + Fluoro with barium
11
Q
Digital fluoro deals with what?
-predominated by 2005
A
-TFT matrices
-Post processing capabilities
12
Q
What are the different pieces of equipment involved with fluoro?
A
-Fluoroscopic screen
-mirrors for viewing (obsolete)
-image intensification (video camera and monitor)
13
Q
Electronic devise mounted above the table and patient and permantely attached to the x-ray tube
A
Image Intensifier
14
Q
Purpose of the image intensification?
A
increase brightness of fluoroscopic images by thousands (8,000 times)
15
Q
What did mirror optics for viewing replaced with?
A
replaced with closed circuit TV systems
16
Q
What is the last image hold for?
A
- a type of radiation protection for the patient
- decrease dose
- the last image is up on the monitor
17
Q
fluoroscopic uses for functional studies:
A
o Gastrointestinal (GI) tract studies
o Angiograms
o Line placements
o Orthopedic surgeries
o IVU
18
Q
Audible timer, radiation protection that beeps saying patient has been in fluoro for 5 minutes?
A
5 minute timer
19
Q
In order to active fluoro what must you do?
A
You have to apply pressure whether is up on the tower or the paddle
20
Q
When applying pressure is considered what?
A
dead man switch
21
Q
A dead man switch is also considered
A
another type of radiation protection
22
Q
Should fluoro be used to preview patient’s radiographic position?
A
NO!!!
23
Q
Where should the patient be shielded for fluoro?
A
from behind the patient since the x-ray tube is below
24
Since you are using a high time in fluoro what happens to your mA?
you are using a low mA
-reciprocity law
24
In what directions can the image intesnifier move?
It can move up and down, side to side
-moves in all directions
25
Why does the image intensifier only go down a certain amount?
Is another type of radiation protection
26
Your beam in fluoro is still what?
the beam is geometry
27
What is the mA range for the fluoroscopic x-ray tube
0.5 to 5.0 mA
28
What is SOD?
Source to object distance
29
What is the source for SOD for fluoro?
The source is the x-ray tube
30
What is the object for SOD in fluoro?
the object is the patient
31
What is the minimum SOD in fixed fluoroscopic equipment (fluoro room)?
15 inches or 38 cm
32
What is 15 inches converted to centimeters?
38 cm
33
What is the minimum SOD in mobile fluoro examination (C-arm)
12 inches or 30 cm
34
What is 12 inches in cm?
30 cm
35
What is known as the foot switch
deadman switch
36
Can you collimate for fluoro?
Yes is known as your shutters also your patient protection
37
components of the image intensifier: correct order
-output phospher
-anode
-electrostatic lenses
-photocathode
-input phospher
38
How do your eyes adjust in fluoro?
-cones
-rods
39
Help you see in bright lights, photopic
Cones
40
Helps you see in low lights, scotopic
Rods
41
Supports the patient and can be changed from a horizontal position to a vertical position
- Equipped with a movable footboard
X-ray table
42
What is the function of input phosphor?
Collecting x-ray photons and converting it to light because there is cesium iodide
42
Image intnsifier starts off from the x-ray table to patient by:
Incoming photons are coming up (exit radiation) to the input phosphor
43
Input phospher is coated with what?
Cesium iodide
43
*concave surface
*approx. 10-35 cm in diameter
*coated with cesium iodide
* converts xray photons to light photons
input phosphor
44
What two things are concave in shape?
Input phosphor and photocathode meaning they could fit on top of each other
44
converts light photons to electrons ; called photoemission
Photocathode
45
Mimics the pattern of light demonstrating the anatomy of the patient emitted by the input phosphor (latent image)
Photocathode
45
made of cesium antimony
Photocathode
46
Narrowing of electrons
- has a negative charge
-slight kvp applied to help keep moving the beam
-acceleration of electrons
Electrostatic lenses
47
-located along the inside of the image intensifier
-charged with a low voltage of 25-35 kvp
-function: accelerate and focus the electrons towards the output phosphor
-focal point: location where the electrons cross as they travel from the photocathode to the anode; changes position when intensifier is operated in normal vs. magnification mode
Electrostatic lenses
48
Electrons pass through the hole in
Anode
49
Do the electrons interact with the anode?
No!!
50
Why is the anode there?
to capture the attraction of negative to positive
50
*positively charged end of the image intensifier
*attracts the photoelectrons due to electrostatic charge
*contains the output phosphor at end
Anode
50
When electrons pass through the anode where are they going?
to the output phosphor
51
After electron passes through the anode it is then converted to light in?
Output phosphor
52
The after the electrons is converted to light in the output phospher what happens next?
Is then converted to your analog-digital-converter which goes on the monitor your manifest image
53
Made of zinc cadmium sulfide
Output phosphor
53
-Made of zinc cadmium sulfide
-approximately 2.5-5.0 cm in diameter
-Function: converts photoelectrons to visible light
Output phosphor
54
The output phospher is coated with a thin aluminum coating because?
To help prevent light leaking back into the intensifier
55
How much lead is in the bucky slot cover?
0.25 mm of lead
56
How much lead in the curtain (lead curtain) (lead drape)?
0.25 mm of lead
57
How much does a regular lead apron have? recommend lead for an apron
0.25 mm of lead
58
What is the recommend lead for a lead apron for fluoro?
0.5 mm of lead
58
In fluoro what comes into place to keep you safe?
time, distance, and shielding
-jump behind the radiologist
58
The closer you are
the more scatter you are going to get
58
If you don't have a wrap around apron what should you not do?
Never turn your back to the beam
-walk backwards
59
is input or output bigger
Input is bigger
60
Accelerate and focus electron pattern across tube
to anode
*primary source of brightness gain (due to acceleration of electron stream and increased kinetic energy)
Electrostatic lenses
61
what does greater voltage to electrostatic lenses do
-increases acceleration of electrons
-shifts focal point away from anode
61
made of zinc cadmium
sulfide
-glass fluorescent screen
Output phosphor
61
Image intensification tube components:
-input screen and photocathode
-electrostatic lenses
-magnification tubes
-anode and output screen
-total brightness gain (minification gain * flux gain)
62
image intensification was introduced in 1948. What was modified.
-higher visual acuity
-uses photopic vision (cones)
-reduced fluoroscopic dose
63
hole in center allows electrons to pass through to output screen
Anode
63
Early fluoroscopes required imaging to be completed in?
-reliance on?
completed in total darkness
-relied on scotopic vision (rod vision)
64
When you go to magmode what are you increasing?
You are increasing your patient dose
65
What is your advantage of going into magmode (magnification)?
increase spatial resolution
65
What is your disadvantge of magmode (magnification)?
increasing patient dose
65
distortion in fluoro is called?
Vignetting
65
because of concave shape you get a distortion called
pincushion distortion
66
When you go to magmode you are only focus where?
You are focus on the center
-getting rid of outer edge distortion
66
When you go into magmode what happens to your focal point?
It changes
66
When you go into magmode your focal point goes closer to what?
goes closer to your input phosphor
66
In the normal mode is closer to what?
closer to output phosphor
67
Magnification =
input screen diameter
over
diameter of input screen used during magnification
-smaller during magmode (surface area)
67
You want everything to go forward because if not what happens?
You get backscatter of light which leads to distortion of the image
67
minification gain x flux gain is known as your?
Total brightness gain
68
Total brightness gain =
minification gain x flux gain
68
measurement of increased image intensity achieved by image intensifier tube
total brightness gain
69
In order to get your total brightness gain you need to get what?
the minification gain and the flux gain
70
Output light intensity is measured in
candela
70
Is known as your input screen diameter squared over your output screen diameter squared
minification gain
71
Results from concentration of large electron volume from input phosphor, being focused down onto small area of output phosphor
Minification gain
71
helps increase that brightness
minification gain
72
minification gain =
input screen diameter ^2/output screen diameter^2
73
Measurement of conversion efficiency of output screen
ex. one electron strikes output screen
-50 light photons emitted per electron striking output phosphor
-flug gain 50
flux gain
74
efficiency of image intensifier
flux gain
75
Increased brightness due to same number of light photons being concentrated on a smaller area
Minification gain
75
flux gain =
output photons over your input photons
76
electrons to light come into play
flux gain
77
Maintains density (brightness) and contrast to compensate for different body thickness
Automatic Brightness Control (ABC)
78
unit for the measurement of light intensity or luminance
candela
79
Which is better?
Fluoroscopic or static radiography resolution
Static radiography
80
Edges of image intensifier have lower resolution due to:
Vignetting
80
Image quality affected by:
-contrast
-resolution
-distortion
-quantum mottle
81
contrast is affected by:
-scatter radiation
-light scatter (penumbra)
81
Controlled by amplitude of video signal
contrast
82
the more scatter you have
the lesser the contrast
83
contrast uses
window width and filtering algorithm
84
unsharpness
penumbra
84
sharpness
umbra
85
differences in density between different body parts
contrast
86
Resolution varies depending on geometric Factors:
SID, OID, minification gain
longer sid, smaller oid
86
blotchy, grainy appearance
-caused by too little exposure
-most commonly remedied by increases mA
Quantum mottle
87
-affected by same parameters as static radiography (primarily oid)
- geometric problems in shape of image intensifier input screen
-concave shape helps reduce distortion
-vignetting or pincushion effect
-not a problem with TFT matrices
-uniform resolution across flat panel detector array
Size distortion
88
Improved by increasing total exposure to intensifier input phosphor
-increase mA
-reduce distance between patient and image intensifier
-increase kvp
Quantum mottle
89
digital fluoroscopic system use
flat panel displays
90
What is the difference with flat panel fluoroscopy ?
-No intensifier tube
-no vignetting
-no dose increase in mag mode
90
Most common viewing system:
Video
-video camera attched to output phosphor
-fluoro video camera uses CCD
-display monitor for viewing
91
Highest energy scatter
-90 degrees angle to incident beam
- same level as radiographer / radiologists gonads
92
what generator is used for digital fluoroscopy
High power generator
93
Newer systems are placing ii with
amorphos silicon (indirect)
93
in digital, Image intensifier output screen coupled to :
TFT (holding your laten image)
93
what is used in digital fluoroscopy to lower noise
pixel binning
94
in digital fluoroscopy, what is connected to each pixel
Photodiodes
95
Use C C D to generate electronic signal
Signal sent to A D C
Allows for post-processing and electronic storage and distribution
Last image hold function
Post-exposure image processing
digital fluoroscopy
95
populary for surgery, er, orthopedic studies
operates the same as stationary units
-pary particular attention to radiation dose when using mobile fluoroscopy
C-arm units
96
patient protection for fluoroscopy
-audible alarm at 5 minutes
-same rules for collimation
-last image hold
97
What is the mR for xray tube and fluoro
-X- ray tube 100 mR
- Fluoro tube 10 mR per min
98
how often should the fluoro system and lead aprons be checked?
-the fluoro system should be checked every 6 months
-the lead gowns should be checked yearly
99
how much aluminum for filtration for fluoro
2.5 mm of aluminum
100
total number of light photons produced by each electron
flux gain
101
the ratio of light photons at the output phosphor divided by the number of input photons
flux gain
