Fluoro part 2
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What is vignetting?
When the center of the image intensifier screen has better resolution, a brighter image and less geometric distortion
Also known as pincussion distortionIts a fall-off in brightness at periphery of an image
What is quantum mottle?
Quantum mottle is a blotchy or grainy apperance caused by insufficient radidation to create a uniform image
How do you fix quantum mottle?
What is mirror optics?
It's a viewing system with a series of lensers and mirrors that magnify and reflect the image to a viewer.
What are the problems that mirror optics have?
Loss of image brightness and only one person can see it at a time.
What is the video system?
It is the most common viewing system that has a closed circuit unit wit hall transmission through cable to avoid broadcast interference.
How does information get across with a videosystem?
Light from output screen converted into electronic signal -> signal sent to video monitor.
What are the two types of video camera tubes used for fluorscopy?
television tube and cathode ray tube
What do television and cathode ray tubes consist of?
A vacuum tube with fluoresecnet phosphors coated on the inside of the front screen as well as an electron gun with deflecting and focusing magnets.
How does the monitor create an image?
It creates the image as the electron gun sprays the pulsed stream of electron for the video camera onto the phosphor screen.
How many lines per second can electron beams scan?
525 hrorriziontal line per 1/30 of a second
What does a cine consist of? What are the two formats they come in?
Has a movice camera positioned to intercept image produced by output screen16mm and 35 mm formats
Whats a the good and bad about cine?
Greater resolution than video systems but MORE patient dose.
What fluorsocopic image recording method cause the most patient dose?
What are some benefits of digital recording?
Beneficial because you have post processing manipulation, storage and sharing
For patient radiation protection, what is the maximum TABLE TOP exposure rate and should not pass?
What is the minimum SOD for mobile an fixed equipment?
- Mobile = 12 inches
- Fixed equipment = 15 inch
How much exposure should a patient approximately receive?
For every 1000 photons reaching the patient, how much scatter is there? How much of the scatter reach the image detector?
- 100- 200 scatter radiation
- 20 scatter reach the image receptor.
Highest amount of scatter occurs at what angle of the incident beam?
What can you do that may help reduce patient exposure?
- Use largest field of view
- Collimate are of interest whne possible
- Use highest acceptable kvp
- Use low dose modes if available
- Use pulsed flouroscopy if aailable.
What is the main source for staff radiation when in a flouro room?
Scatter radiation from the patient.
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