Kamis, 18 November 2010

Mammography

1.1.14 Mammography
• basic principles of soft tissue and breast imaging
• types of mammography x-ray units
• emission spectra with different anode and filter materials eg molybdenum
tube and filter
• geometric unsharpness as a limiting factor
• recording system: film screen, digital
• magnification techniques
• alternative breast imaging: radionuclide imaging , US, MR
• principles and applications of stereotaxis


Xeroradiography is a type of x-ray in which a picture of the body is recorded on paper rather than on film. In this technique, a plate of selenium, which rests on a thin layer of aluminium oxide, is charged uniformly by passing it in front of a 'scorotron'.
As X-ray photon impinges on this amorphous coat of selenium, charges diffuse out, in proportion to energy content of the X-ray. This occurs as a result of photoconduction. The resulting imprint, in the form of charge distribution on the plate, attracts toner particles, which is then transferred to reusable paper plates. In contrast to conventional X-rays, photographic developers are not needed. Hence the term xeroradiography; 'xero' meaning dry in Greek. It requires more radiation exposure. Its use is in mammography.
Xeromammography is a form of xeroradiography

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