Digital Mammographic Systems

1292 Words Jan 26th, 2018 5 Pages
While screen film has been the standard detector used in conventional mammography, developments in technology have opened avenues to more advanced imaging techniques using digital mammography. The motivation behind advancing from screen film imaging to digital mammography include potentially lower dose, improved image quality, computer aided diagnosis and soft copy review and digital archiving.
II. Types of digital detectors and their working principles
There are two categories of digital detectors for mammography which are indirect and direct digital detectors. Indirect conversion requires an intermediate step: X-ray energy is first converted into light by a scintillating medium before conversion into electrical charges by a photodiode. Direct digital detectors on the other hand utilize a direct conversion method where X-rays are absorbed and electronic signals are created instantaneously in a single step within a semiconductor device. According to Vedantham (2000) 1, indirect systems suffer from resolution degradation caused by the scatter of light within the scintillator during the conversion compared to direct systems.
Phosphor flat panel detector is a type of indirect digital detector. The working principle of this type of detector involves x-rays being absorbed by a layer of thallium activated cesium iodide phosphor CsI(Tl) that is eventually deposited onto photodiodes. The…