CHAPTER 25 : FLUOROSCOPY BUSHONG

• The fluoroscope is used for

  the examination of moving internal structures and fluids.
• Angiography is used to


  visualize vessels.
• Interventional radiology includes

  neuroradiology and vascular radiology.
• ABC stands for


  AutomaticBrightnessControl

  - Brightness level maintained automatically by varying the kVp, the mA, or sometimes both.
• Brightness level is maintained automatically by

  varying the kVp, the mA, or sometimes both.
• AERC stands for


  AutomaticExposureRateControl

  - Maintains the radiation dose per frame at a predetermined level.
• Illumination levels are measured in

  units of lumen per square meter or lux.
• Visual Physiology


  rods and cones are responsible for the sensation of vision
• Cones are used primarily for

  daylight vision, also called photopic vision.
• Rods are used primarily for

  night vision, also called scotopic vision.
• The influence of kVp and mA on fluoroscopic image quality is ____________ to their influence on radiographic image quality. Generally, _______ kVp and _______ mA are preferred.

  similar, high, low
• Why is the fluoroscopic mA not given?

  Because this value varies according to patient thickness and the response of the ABC system
• IMAGE INTENSIFICATION:


  •Input phosphor- CsI- Cesium iodide

  •The photocathode emits electrons when illuminated by the input phosphor

  •The output phosphor is the site where accelerated electrons interact and produce light

  •Electrostatic focusing lenses, negative charge focuses the electron stream

  •Multifield image intensifiers produce different magnification of the image

  •25/17/12 cm trifield tubes

  
• What is the number of output light photons over the number of input x-ray photons?

  Flux gain
• What is the square of the diameter of the input phosphor over the diameter of the output phosphor?

  Minification gain
• What is the Minification gain multiplied by the Flux gain?

  Brightness gain
• The brightness gain of most image intensifiers is

  5,000 to 30,000.
• The conversion factor is approximately ______ times the brightness gain.

  0.01
• The Conversion Factor is


  Output phosphor illumination over Input exposure rate.
• Fluoro images are viewed on a

  television or flat panel monitor.
• The spot-film camera uses ______mm film.

  105
• The _______________________ ___________ was used almost exclusively in cardiac catheterization, but that use has been largely replaced by ____________ _______________.

  cineradiography camera, digital imaging
• What is veiling glare?

  internal scatter radiation in the form of x-rays, electrons, and particularly light that can reduce the contrast of image intensifiers.
• Magnification Mode Results in

  Better special resolution

  Better contrast resolution

  Higher patient radiation dose
• What is vignetting?


  reduction in brightness at the periphery.

  - the portion of any image that results from the periphery of the input phosphor is inherently unfocused and suffers fromvignetting
• With television monitoring systems, the output phosphor of the image intensifier tube is _____________ coupled to a television camera tube.

  directly
• The ___________ is the television camera tube that is used most often.

  vidicon
• A television camera tube or CCD converts the light signal from the output phosphor to an

  electronic signal.
• The magnitude of the video signal is ____________________ to the intensity of light from the output phosphor.

  proportional
• FLUOROSCOPIC IMAGE MONITORING:


  •The simplest method is to use a bundle of fiberoptics. The fiberoptics bundle is only a few mm thick and contains thousands of glass fibers per square mm of cross-section. It cannot accommodate cine or photospot cameras.

  •Lens coupling is required for the above mentioned. The objective lens accepts light from the output phosphor and converts it into a parallel beam. It uses a beam splitting mirror. One portion goes to the TV camera while the other portion goes to the film camera. It allows for view and recording.

  •The TV monitor is a CRT

  •Modulation is a change in a quantity or signal in response to another quantity or signal and is widely used in medical imaging.
• The intensity of the electron beam is modulated by a


  control grid.
• The objective lens accepts light from the output phosphor and converts it into

  a parallel beam.
• The phosphor is composed of linear crystals that are aligned _____________________ to the glass envelope to reduce lateral dispersion.

  perpendicularly
• How is the television image on the monitor formed?

  visible light is transformed into an electrical video signal
• Video monitoring uses a rate of _____ frames per second.

  30
• In fluoroscopic image monitoring, the movement is in a

  raster pattern.
• The ___________ the bandpass, the ___________ the horizontal resolution

  higher, better
• IMAGE RECORDING:


  •Cassette loaded spot film

  •The photo spot camera uses 70mm and 105mm which is better image quality but more exposure

  •105mm photo spot camera exposure is only ½ the exposure of Cassette loaded spot film
• The photo spot camera uses ____mm and _____mm which is better image quality BUT _______ exposure.

  70, 150, more
• A 105mm photo spot camera exposure is only ___ the exposure of a Cassette loaded spot film.


  ½