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22 Cards in this Set
- Front
- Back
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inventor of the fluoroscope and year |
Thomas Edison, 1896 |
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what is fluoroscopy used for? |
to examine moving internal body structures and fluids |
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What are the 3 main unit of conventional fluoroscopy? |
1. X-ray tube and Generator, 2. Image intensifier, 3. Video monitoring System |
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6 main components of the image intensifier |
1. Glass Envelope 2. Input Phosphor 3. Photo-cathode 4. Electrostatic Lenses 5. Anode 6. Output Phosphor |
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What is the purpose of the input phosphor? |
Converts x-ray photons to visible light |
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What is the input phosphor construction? |
Sodium activated cesium iodide (CsI:Na) on a glass or aluminum base |
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What is the input phosphor surface shape? |
convex surface |
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What is the purpose of the photo-cathode? |
converts light from the input phosphor to electrons |
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What is the difference between photo-emission and thermionic emission? |
Photo-emission uses light and thermionic uses heat for production of electrons |
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What charge does the electrostatic lenses have? |
negative |
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What are the two purposes of electrostatic lenses? |
focuses electrons onto the output phosphor and accelerate electron speed = kinetic energy |
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What is the purpose of the anode? |
sets up a strong potential difference between input and output phosphors |
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What is the unit of potential difference? |
volts (V) |
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What is the purpose of the hole in the center of the anode? |
to permit the accelerated electrons to pass throughonto the output screen.
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What is the charge of the anode? Why is this important? |
Positively 25-35 kVp charged to highly attract the electrons |
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What is the purpose of the output phosphor? |
turns electrons into visible light with huge increase in brightness but decrease in image size |
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What is the construction of output phosphor? |
silver activated cadmium zinc sulfide |
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What is the size differences of the output phosphor to the input? |
The output is smaller than the input |
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What is the relationship between the input phosphor diameter and magnification? |
increase input diameter = less magnification |
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what is the difference between an x-ray and a gamma ray? |
their origin. |
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What affects brightness levels? |
mA, kVp, ABC (Automatic Brightness Control), Variable tube current, Variable pulse width |
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As magnification increases image brightness is lost, what should you do to mA to compensate? What happens to pt dose? |
increase mA, and pt dose increases
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