tomography
problems with tomography
3-D image >2-D image
all images are superimposed
Makes it difficult to view deep structures
principle of tomography
tomography uses different levels of blurring to view certain structures of an image (controlled blurring)
tomography is not a method used to improve sharpness
essentials of linear tomography
x-ray beam mounted on on a rigid rod so that it can rotate around the fulcrum
the tube moves in one direction and the image receptor moves in another direction
position of the fulcrum can be raised or lowered
the x-ray tube swings around the arc of a circle
Tomography
structure above and below the fulcrum are blurred
tomography is somewhat subjective
was used for urography to better visualise the kidneys
section of thickness depends on the angle of swing
problems with tomography
increased patient dose
lowered KVP which reduces contrast
orthopantogram is used in dental radiology to visualise the mandible
uses a curved image receptor