3 X-Rays were discovered by Roentgen in 1895 They are part of electromagnetic spectrum and are invisibleX- rays are described as consisting of wave packets of energy. Each packet is called a photon and is equivalent to one quantum of energy.
4 Longer X-rays have less penetrating power The energy carried by x-rays can be attenuated by matter i.e absorbed or scattered
5 An X-ray beam is made up of millions of photons of different energies The diagnostic X-ray beam varies in its intensity and guantityThe factors affecting the intensity and/or the quantity of the beam are kV, mA, distance from the target, length of exposure, filtrationr
6 Dental X-ray generating equipment A tubeheadPositioning armA control panel and circuitry
7 Ideal requirements Safe and accurate Capable of generating X-rays in the desired rangeSmallEasy to manoeuvre and positionStableEasily folded and storedSimple to operateRobust
10 Main features and requirements of an x-ray tube The production of X- rays can be summarized as the following sequence of eventsThe filament is electrically heated and a cloud of electrons is produced around the filamentThe high voltage ( potential difference) across the tube accelerates the electrons at very high speed towards the anodeThe focusing device aims the electron stream at the focal spot on the targetThe electrons bombard the target and are brought suddenly to restThe energy lost by the electrons is transferred into either heat (about 99 %) or X-rays (about 1 %)The X-rays are emitted in all directions from the target.Those emitted through the small window in the lead casting constitute the beam used for diagnostic purposes.