Fluoroscopy

• Fluoroscopy:

  • dynamic
  • there is no difference on the X-ray tube between fluoroscopy and conventional radiography
• source in fluoroscopy:

  • continuous low-power X-ray beam
  • ionizing radiation
• detector used in fluoroscopy: image intensifier tube
• image intensifier tube: receives the image-forming x-ray beam and converts it into a visible-light image of high intensity.
• X-ray image intensifier amplifies the output image.
• X-ray Tube in fluoroscopy:

  • can either be top/below of the patient
  • operates at less than 5 mAs
• 1. Detector: image intensifier tube
  2. X-ray Tube
  3. Flat panel display (monitor)
• Conventional Radiography: has the capacity to exceed its exposure factors of more than 50 mAs
• Fluoroscopy: required to only produce less than 5 mAs. However, due to continuous operation (maximum of 5 minutes), exposure is still higher than that of conventional radiography
• Dead man’s switch: like exposure switch; if you press this switch continuously until maximum time is reached (5 minutes), the machine will automatically shut down and will not produce x-rays anymore
• Flow of image intensifier tube:

  • x-ray tube to patient to input phosphor (cesium iodide) to photocathode to anode to output phosphor (monitor)
• Image Attributes of fluoroscopy: continuous acquisition of a sequence of X-ray images over time results in a real-time X-ray movie.
• fluoroscopy may use inverted grayscale: white for air, black for bones
• fluoroscopy can image anatomic motion and provide real-time image feedback during procedures
• fluoroscopy is useful for monitoring and carrying out barium studies of the gastrointestinal tract, arteriography, and interventional procedures such as positioning catheters
• fluoroscopy provides lower quality moving projection radiograph
• input phosphor: x-rays will be converted to light (light photons of x-rays)
• photocathode: converts light to electron -- AKA photoemission
• photoemission: electron emission that follows light stimulation
• anode: electron will be converted to image-forming light