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How do radiographers make up for fluoroscopys low contrast?
How are illumination levels measured?
What are the two structures of the eye responsibel for vision?
Rods and Cones
Describe the difference between Rods and Cones
Rods- sensitive to light, used for scotopic (night), do not percieve color as well as cones
Cones- respond to brighter light, used for photopic (daylight) vison, able to percieve fine detail, can distinguish between brightness levels
What is visual acuity?
ability to percieve fine detail
What is contrast perception?
Ability to detect difference between light levels
What are the 5 parts of the image intensifier tube?
- - input phosphor
- - photocathode
- - electrostatic lenses
- - accelerating anode
- - output phosphor
What is theinput phosphor made out of and what is it's role?
Cesium iodide- convert x-rays to light
What is the role of the photocathode?
- emits electrons when stimulated by light
- - directly proportional
What is the role of the electrostatic lenses?
- Negatively charged elctrodes, plated on the inside surface of the glass
- - Focuses the elctrons from photocathode to the output phosphor
Whate is the role of the accelerating anode?
- Positively charged, located in the neck of the tube
- Accelerates electrons towards the output phosphor
What is the output phosphor made of and what is its role?
- Made of zinc cadmium sulfite
- converts electrons from photocathode into light
Light photons are multiplied by the output phosphor, resulting in a much brighter image
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