RAD 350 Chapt. 25 Fluoroscopy Fluoro’s primary function is to enable one to view the patient in “real time” with dynamic motion Invented by Thomas Edison in 1896 – Utilized a conventional x-ray unit with a fluorescent screen that would convert the x-rays (remnant beam) to low level light the radiologist could view

Image Intensified Fluoro

II Fluoro Increased image brightness with II over direct fluoro is the biggest advantage of II – Usually controlled by “automatic brightness control” (ABC that the radiologist can control)

Image Intensifier Dang it – I couldn’t find a picture, so draw the dang thing! – Input phosphore – Photocathode (photo emission) – Evacuated glass envelope – Electrostatic focusing lens (neg. charge) – Anode – Output phosphor

Image intensifier (I lied – here is the picture)

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

Fluoro Magnification Most fluoro II units have dual input phosphor sizes (9” and 6” {27/17 cm}) – Some have “tri” input (trifield tubes 27/17/12 cm) The crossover of the electron stream’s distance from the output phosphor determines the amount of magnification Mag mode = better spatial resolution, better contrast resolution and HIGHER PT. DOSE!!!

TV/Monitor Viewing Must “couple” the output phosphor to a TV camera tube or CCD/TFT – Vidicon tube is the MOST frequently used tube Image orthocon and plumbicon are also used

Other viewing/imaging devices Fiber optics and beam splitters are used to help direct the digitized image to the various destinations (TV monitor, photospot film camera, VCR/DVD recorder, cine camera)

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

Conventional Fluoro Techniques (not digital fluoro) Fluoro usually is operated at 5 mA and uses the highest OPTIMUM kVp Protective Fluoro Measures – Bucky slot cover – Lead curtain – 5 min. back up timer – Lead gloves and aprons (5mm pb) – secondary barriers – Distance