Fluoroscopy
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| show | Luminous intensity per unit of projected area of source or the light emitted or scattered from a particular source.
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| Which units measure luminance? Papp p45 | show 🗑
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| show | Greater than 170 nit
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| show | Greater than 100 nit
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| Describe CONE vision... Selman p259 | show 🗑
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| Describe ROD vision. | show 🗑
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| Describe the anatomy of the eye. | show 🗑
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| Fluoro historical perspective Orth p342 | show 🗑
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| show | The amount of luminous flux incident per unit area, or the amount of light projected onto a given surface (brightness on the page, not the actual light source)
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| show | The study of light and how it interacts with your eye
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| What is image contrast? Papp p46 | show 🗑
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| show | distribution of tissue densities/physiologic changes present in anatomic part being imaged. Influenced by internal factors (tissue density) and external factors (rad quality, scatter, contrast agents, etc)
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| show | Dynamic imaging of organs
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| show | x-ray tube (under table), movable table (carbon fiber), foot board, image intensifier, camera tube and viewing device
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| What affects the TV fields generated per second? | show 🗑
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| show | two interlaced fields
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| show | 262.5
pLUS
262.5
EQUALS
525
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| show | lower tube current
kVp (depends on exam)
patient dose - increased due to exposure time
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| show | Single contrast requires use of increased kVp due to higher density of contrast material.
Double contrast needs less kVp due to presence of air with denser contrast material
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| show | 1 foot candle = 10.8 lux (reading room brightness)
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| Compare a sunny day in foot candles with an OR. | show 🗑
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| show | Began with first fluoro devices - due to using barium platinocide paper which fluoresces very dimly. Radiologist had to adapt the eyes to using ROD vision - 20-30 min in dark then wear red goggles. Exam performed in dark room.
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| show | To increase the brightness of the fluoroscopic image; increases it up to 1,000x
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| show | Input phosphor, photocathode, electrostatic focusing lenses, accelerating anode, output phosphor. The device converts x-rays to electrons to light photons.
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| show | a vacuum sealed glass envelope, surrounded by lead equivalent 2 mm housing.
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| show | kV (70-90)
mA (0.5-5)
anatomy being studied
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| show | patient thickness
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| show | 70-90 kVp and 0.5 - 5mA
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| Describe the image intensifier input phosphor? | show 🗑
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| Describe the Photocathode. | show 🗑
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| Describe the Electrostatic focusing lenses | show 🗑
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| show | To reduce distortion by maintaining the distance between all points on the input screen and the output phosphor.
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| show | The accelerating anode attracts the electron beam to the output phosphor which consists of Zinc Cadmium Sulfide (znCdS); the output phosphor emits light when the electrons hit it. It’s about 2.5 - 5cm in diameter
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| show | Zinc Cadmium Sulfide (ZnCdS); it's about 2.5-5cm in diameter
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| What is the principle of the image intensifier? | show 🗑
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| What is the advantage of Cesium Iodide as the input phosphor? | show 🗑
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| Explain how the electrostatic lenses work. PP p5 | show 🗑
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| show | ratio of # of light photons/output phosphor to # of x-ray photons/input phosphor. Multiplication of photons in output screen (conversion efficiency) measurement of light photon gain from conversion
FG = # output light photons / # of input x-ray photons
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| show | ratio of light from input phosphor to light at output phosphor (measurement of the increase in intensity/brightness) due to concentration of electrons to smaller surface
MG = Input Diameter sq / Output Diameter sq
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| show | measurement of the gain of image brightness; ability of the II to increase the illumination level of the image; entire brightness change from input to output
BG = MG x FG
Usually 5,000 - 30,000 but decreases 10% per year (age/use)
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| What is the total brightness gain with a minification gain of 36 and a flux gain of 60? | show 🗑
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| show | 15 sq / 2.5 sq
225 / 6.25 = 36
Minification gain = 36
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| show | 4,500 / 50
Flux gain = 90
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| Define CONVERSION FACTOR. Orth p348/ PP p7 | show 🗑
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| What is multifield image intensifying? | show 🗑
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| Why does changing the diameter of the input phosphor change the size of the image? | show 🗑
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| How does the fluoro system control brightness? Orth p348, Selman p268 | show 🗑
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| show | maintains image brightness automatically by varying the kVp, mA or both
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| show | outside Image Intensifier - in pickup tube
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| Why is the image magnified during multifield imaging? | show 🗑
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| show | Mag mode reduces space used on surface of input phosphor
Selman p263 fig 20.5 Orth's figure is confusing
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| Why is patient dose increased? | show 🗑
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| What type of image quality results from magnification? | show 🗑
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| Why is brightness reduced during magnification? | show 🗑
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| describe magnification factor. Orth p349 | show 🗑
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| how does magnification mode affect minification gain? | show 🗑
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| How does using mag mode affect electrostatic lenses? | show 🗑
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| show | 1.5 to 4 X magnification
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| How does mag mode affect patient dose? | show 🗑
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| Describe electrostatic focusing lenses. Orth p346 | show 🗑
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| Describe output phosphor. Orth p346-347 | show 🗑
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| show | Radiant energy that strikes/crosses surface per unit of time or radiant energy emitted by a source per unit time;
Measured in WATTS
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| show | input screen diam / input screen diam during magnification
25 / 15 = 1.667
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| show | MF = SID / SOD
78 - 57 = 21 = SOD
78 / 21 =
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| SOLVE: What is the magnification for an image view with an image intensification tube where the input screen diameter is 9" and 6" diameter is used in mag mode? | show 🗑
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| What is the maximum entrance exposure rate during fluoro? Papp p155 | show 🗑
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| show | Orthicon - old technology not used much now
Plumbicon - uses lead oxide as target phosphor - SHORT lag time, LOW BRIGHTNESS
Vidicon - uses antimony trisulfide as target phosphor - LONGER lag time (helpful in GI studies), HIGH BRIGHTNESS
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| show | Charge Coupled Device
solid state device that converts visible light to electrons;
replaces vidicon type camera tubes
PROS - smaller, longer life, rugged, more sensitive
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| Describe camera tube. PP p12 Orth p352 Papp p149 fig7.5 | show 🗑
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