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RAD 354 Chapt . 21 Fluoroscopy

RAD 354 Chapt . 21 Fluoroscopy. Fluoro’s primary function is to enable one to view the patient in “real time” with dynamic motion. Fluoro was first invented by Thomas Edison in 1896.

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RAD 354 Chapt . 21 Fluoroscopy

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  1. RAD 354 Chapt. 21 Fluoroscopy • Fluoro’s primary function is to enable one to view the patient in “real time” with dynamic motion

  2. Fluoro was first invented by Thomas Edison in 1896 • Utilized a conventional x-ray unit with a fluorescent screen that would convert the x-rays exiting the patient to low level light the radiologist could view

  3. Image Intensified Fluoro

  4. II

  5. II Tube Parts • Input phosphor • Photocathode (photo emission) • Evacuated glass envelope • Electrostatic focusing lens (neg. charged!!!) • Anode • Output phosphor

  6. II Fluoro • Increased image brightness with II over “direct” fluoro is the biggest advantage of II • Maintains OD by “automatic brightness control” (ABC) that the radiologist can preset and control

  7. Eyes use rods and cones • Photopic vision – daylight vision uses the CONES • Scotopic vision - night time vision and uses the RODS

  8. Fluoro Techniques • Fluoro usually is operated at 5 mA and uses highest optimum kVp • Back up timer = 5 minutes • Protective Fluoro measures • Bucky slot cover • Lead curtain • Lead gloves and aprons (secondary barriers) • Distance

  9. Gain • Minification gain (ratio of input to output sizes) • Flux gain – ratio of # of inpupt PHOTONS to output LIGHT PHOTONS • Brightness gain (total brightness gain) = minification gain X flux gain

  10. Fluoro Magnification • Most fluoro II units have DUAL input phosphor sizes (9” and 6” {27/17cm}) • Some have TRI sizes input (trifield tubes 27/17/12cm) • The crossover of the electron stream distance from the output phosphor determines the amount of magnification • Mag mode = BETTER SPATIAL RESOLUTION, better contrast, HIGHER pt. dose!

  11. TV Monitoring • Must “couple” the output phosphor to a TV camera tube or photomultiplier tube • Vidicon is the MOST frequently used tube – plubicon and image orthocon are also tube types • Fiber optics and beam splitters are used to help direct the digitized image to the various destinations (TV monitor, photo spot film, VCR/CD recorder, cine camera)

  12. Vidicon Camera (tube)

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