Jennifer Hodges

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Jennifer Hodges
2010-11-06 21:20:31

Gary's Tomography
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  1. What is radiographic tomography?
    Radiographic procedure that brings into focus only those anatomical structures that lie in a specified plane of interest and blurs those structures outside the plane thus enhancing radiographic contrast.
  2. What are the five tomographic movements, and which one is the most used today?
    • Linear
    • Circular
    • Elliptical
    • Hypocycloidal
    • Trispiral
    • LINEAR
  3. In tomography, what is the relationship between the x-ray tube and the image receptor movements?
    X-ray tube moves in one direction, and the image receptor moves in the opposite direction.
  4. Explain the concept of linear tomography to include the terms fulcrum, object, plane, tomographic angle, and section thickness (tomographic Layer).
    The fulcrum is an imaginary pivot point about which the x-ray tube and image move. The fulcrum lies in the object plane. and only those structures within the plane are focused. The angle of movement of the x-ray tube determines section thickness with larger angles resulting in thiner section thickness (or tomographic angles). The larger the angle, the more the blurred the images outside the object plane. The further from the object plane a structure is, the more blurred the image of that structure.
  5. What is the principle advantage of tomography? Disadvantage?
    • Advantage-Improved radiographic contrast
    • Disadvantage-Increase patient dose
  6. What is zonography, and when is it used?
    Tomography with an angle less than 10 degrees. Used when subject contrast is low as in chest and renal exams.
  7. What is panoramic tomography, and when is it used?
    Special tomographic exam used for dental surveys and mandible exams and other bony structures of the head.
  8. Explain magnification radiography.
    Radiographic procedure used by vascular radiologists and neuroradiologists using a larger OID while maintaining a constant SID. Requires use of small focal spot to maintain detail. Grids normally not required due to increased OID reducing scatter radiation reaching image receptors. Results in increased patient dose because the patient is closer to the radiation source.