Fluoroscopy Exam Rated A | Questions with 100%
Correct Answers
How is fluoroscopy used in angiography?
To position the system for the recording of images of contrast material being injected via
catheter
How is fluoroscopy used in angioplasty?
To provide imaging guidance for interventional procedures?
Three types of fluoroscopy cameras
analog vidicon, CCD or CMOS (Complementary metal-oxide semiconductor)
"Real time" imaging frame rate
30 fps, about the same as old analog TVs
Fluoroscopic imaging chain diagram
Copper filtration is combined with (higher/lower) kVs for dose reduction in angiography
lower
When would you use an attenuator wedge in a fluoroscopic system?
To reduce bright regions, such as those created in the pulmonary space between the heart and
chest wall
Dose difference per image between fluoroscopy and radiography
,fluoroscopy: 9-17 nGy (1-2 uR) per image
radiography: 5-9 uGy (.6-1 mR) per image
Four principle components of an II
1. vacuum housing to keep air out and allow unimpeded e- flow
2. an input layer that converts the absorbed incident x-rays into light, which in turn releases e-
3. an e- optics system that accelerates and focuses the e- emitted by the input layer onto an
output layer
4. an output phosphor that concerts the accelerated e- into a visible light image
II Diagram
G1-3 are additional focusing electrodes
II Input Screen Diagram
The vacuum window of an II is typically made of what?
~1mm Al
Why is the input surface of an II curved?
To withstand the force of air pressing against it (contains vacuum). A 35 cm FOV can withstand
a ton of atmospheric air pressure
What is the support layer of the II Input Screen?
Commonly 0.5 mm Al, supports the input phosphor and photo-cathode layers. The first
component in the electronic lens system, its curvature designed for accurate e- focusing
Most common material for II phosphor
, CsI, can be formed into columnar "light pipes." As a result, the phosphor can be quite thick and
still produce high res. They are approx 400 um tall and 5 um wide and formed by vacuum
deposition of CsI onto substrate. They contain a trace amount of Na, causing them to emit blue
light. The K-edges of Cs (36 keV) and I (33 keV) are well positioned with respect to the
fluoroscopic x-ray spectrum, which contribute to high x-ray absorption efficiency
K-edge of cesium (CS)
36 keV
K-edge of Iodine (I)
33 keV
Photocathode of II
A thin layer of antimony and alkali metals (such as Sb2S3) that emits e- when struck by visible
light (10-20% conversion efficiency)
Electronic gain of II
When the kinetic energy of an e- is dramatically increased by acceleration due to a voltage
difference between the anode and cathode
When e- travel from the photocathode to the output phosphor of an II, they are
(magnified/minified) and the light intensity (increases/decreases)
minified, increases. The 15-35 cm diameter input image is focused onto a 2.5 cm (1") diameter
circle (think magnifying glass)
What causes pincushion distortion of a fluoro image?
Correct Answers
How is fluoroscopy used in angiography?
To position the system for the recording of images of contrast material being injected via
catheter
How is fluoroscopy used in angioplasty?
To provide imaging guidance for interventional procedures?
Three types of fluoroscopy cameras
analog vidicon, CCD or CMOS (Complementary metal-oxide semiconductor)
"Real time" imaging frame rate
30 fps, about the same as old analog TVs
Fluoroscopic imaging chain diagram
Copper filtration is combined with (higher/lower) kVs for dose reduction in angiography
lower
When would you use an attenuator wedge in a fluoroscopic system?
To reduce bright regions, such as those created in the pulmonary space between the heart and
chest wall
Dose difference per image between fluoroscopy and radiography
,fluoroscopy: 9-17 nGy (1-2 uR) per image
radiography: 5-9 uGy (.6-1 mR) per image
Four principle components of an II
1. vacuum housing to keep air out and allow unimpeded e- flow
2. an input layer that converts the absorbed incident x-rays into light, which in turn releases e-
3. an e- optics system that accelerates and focuses the e- emitted by the input layer onto an
output layer
4. an output phosphor that concerts the accelerated e- into a visible light image
II Diagram
G1-3 are additional focusing electrodes
II Input Screen Diagram
The vacuum window of an II is typically made of what?
~1mm Al
Why is the input surface of an II curved?
To withstand the force of air pressing against it (contains vacuum). A 35 cm FOV can withstand
a ton of atmospheric air pressure
What is the support layer of the II Input Screen?
Commonly 0.5 mm Al, supports the input phosphor and photo-cathode layers. The first
component in the electronic lens system, its curvature designed for accurate e- focusing
Most common material for II phosphor
, CsI, can be formed into columnar "light pipes." As a result, the phosphor can be quite thick and
still produce high res. They are approx 400 um tall and 5 um wide and formed by vacuum
deposition of CsI onto substrate. They contain a trace amount of Na, causing them to emit blue
light. The K-edges of Cs (36 keV) and I (33 keV) are well positioned with respect to the
fluoroscopic x-ray spectrum, which contribute to high x-ray absorption efficiency
K-edge of cesium (CS)
36 keV
K-edge of Iodine (I)
33 keV
Photocathode of II
A thin layer of antimony and alkali metals (such as Sb2S3) that emits e- when struck by visible
light (10-20% conversion efficiency)
Electronic gain of II
When the kinetic energy of an e- is dramatically increased by acceleration due to a voltage
difference between the anode and cathode
When e- travel from the photocathode to the output phosphor of an II, they are
(magnified/minified) and the light intensity (increases/decreases)
minified, increases. The 15-35 cm diameter input image is focused onto a 2.5 cm (1") diameter
circle (think magnifying glass)
What causes pincushion distortion of a fluoro image?
