Conventional Fluoroscopy Flashcards
(37 cards)
What is fluoroscopy?
Fluoroscopy is a specialized imaging technique that provides real-time X-ray imaging of a patient’s internal structures
When was fluoroscopy invented?
First introduced by Thomas Edison in 1896
What are the core purposes of fluoroscopy?
The core purposes of fluoroscopy are:
* Observe anatomy in motion
* Locate and position anatomical structures or medical devices
* Guide interventional procedures
What is a key feature of fluoroscoping imaging?
Uses an image intensifier tube which converts the xray to light and then makes it visible by brightening it and making smaller
What are the key steps in the image intensification process?
The key steps in the image intensification process include:
* Input Stage
* Acceleration and Focusing
* Output Stage
How does the Input stage work?
- X-rays enter the input phosphor (typically cesium iodide)
- X-ray energy is converted to light
- Light interacts with photocathode to produce electrons
How does Acceleration and Focusing work?
- Electrons are accelerated through 25,000-30,000 volts
- Electrostatic focusing lenses guide and narrow the electron beam
- Each 60 kVp photon produces approximately 200 photoelectrons
How does the output stage work?
- Electrons strike output phosphor (zinc-cadmium sulfide)
- Final image is produced on a smaller, brighter screen
- Image is captured by video camera or digital detector
What is brightness gain in fluoroscopy?
The increase in brightness produced by the II
What are the two causes leading to a brighter image?
Flux gain and minification gain
What is flux gain?
The number of light photons at the output phosphor vs the number of xrays at the input phosphor
What is a typical flux gain?
100 or higher
What does flux gain depend on?
Tube voltage (usually 25 kV)
What is Minification Gain?
Minification Gain results from image size reduction, typically providing a 35-80× brightness increase
What size do the input screen range from?
6-12 inches
What is the size of the output screen?
Typically 1 inch
How is brightness gain measured?
Brightness Gain = Minification Gain × Flux Gain
What factors affect image resolution in fluoroscopy?
Factors affecting resolution include:
* Input phosphor size
* Electronic focusing
* Output phosphor characteristics
* Video system capabilities
What are contrast limitations in fluoroscopy?
- Unabsorbed X-rays reaching output phosphor
- Light scatter within system
- Veiling glare effects
What are common image artifacts in fluoroscopy?
- Pincushion Distortion
- Vignetting
What causes Pincushion Distortion?
Pincushion Distortion is caused by curved input phosphor to flat output phosphor conversion
Where is pincushion distorion more noticeable?
At the image periphery
What is Vignetting?
Brightness decrease at image periphery
What does vignetting result from?
Electron focusing characteristics
