6 Questions
What is the primary objective of tomography?
To eliminate structures above and below the focused section or focal plane
What is the main limitation of conventional tomography?
Inability to remove all unwanted planes
What is the effect of the open geometry of the x-ray beam on tomography images?
Degrades image contrast due to scattered radiation
What is the limitation of radiographic film in demonstrating soft tissue contrast?
It can only discriminate x-ray intensity differences of 5% to 10%
What is the movement of the x-ray tube and film in conventional tomography?
Simultaneous movement in opposite directions
What is the name sometimes used to distinguish conventional tomography from CT?
Geometric tomography
Study Notes
Conventional Tomography Limitations
- Conventional tomography is used to overcome superimposition in radiography, but it has its own limitations.
- Geometric tomography is another term used to describe conventional tomography to distinguish it from CT.
- The method involves moving the x-ray tube and film simultaneously in opposite directions to blur unwanted sections and keep the desired layer in focus.
- The ultimate goal of tomography is to eliminate structures above and below the focal plane, but this is difficult to achieve.
Limitations of Conventional Tomography
- One of the major limitations is persistent image blurring that cannot be completely removed.
- Degradation of image contrast occurs due to scattered radiation created by the open geometry of the x-ray beam.
- Film-screen combinations also contribute to image degradation.
- Conventional tomography fails to demonstrate slight differences in subject contrast, characteristic of soft tissue.
- Radiographic film lacks sensitivity to resolve small differences in x-ray intensity (typically 5% to 10%).
Learn about the limitations and methods of conventional tomography, also known as geometric tomography, in radiography. Discover how it overcomes the problem of superimposition and achieves focused images.
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