tomography Flashcards
Tomography is also known as
body section radiography
A special x-ray technique that blurs out the shadows of superimposed structures to show more clearly the principle structures examined
Tomography
The object being examined is not focused in the normal sense, but rather its ________ is enhanced by the blurring of the adjacent structures.
radiographic contrast
Other names for Tomography
Planigraphy, stratigraphy, Laminography
Simplest type of tomography
Linear tomography
Essential ingredients for linear tomography
- X-ray tube
- movable bucky
- rigid connecting rod
Rigid connecting rod rotates about a ____
fixed fulcrum
Tube and cassette move in ______ directions
opposite
_____ is the only point in the system that remains stationary
fulcrum
Uses a _________ focal spot for improved recorded detail
small
Fulcrum
The imaginary pivot point about which the tube and film move. it lies within the object or focal plane
object/focal plane
- The plane of maximum focus.
- All objects outside this plane will be blurred due to motion unsharpness caused by the movement of the tube and the cassette.
Grossman principle
- Fulcrum is stationary
- Table is raised or lowered
planigraphic principle
- adjustable fulcrum system
- fulcrum is raised or lowered
- Table/patient remain stationary
Tomographic angle determines:
thickness of the tomographic cut
Tomographic angle
The angle of the tube movement (while the xray tube is energized) measured in degrees.
The larger the angle, the ______ the thickness
smaller
The smaller the angle, the ______ the thickness
larger
Types of tube motion
Linear, circular, elliptical, figure 8, hypocycloidal, spiral, trispiral
How do you determine the level of the tomo scout
- measure the patient
- divide the measurement by 2
- subtract 2 cm from that number (because the kidneys are retroperenel)
Advantage
increases radiographic contrast
disadvantage
increases patient dose due to the tube being energized for the entire length of travel
Tomography superceded by
ct and mri
