Line spectra will generally be sharp and distinct positioned at a particular wavelength whereas a continuum will be spread over a wider area of varying wavelengths.Current that passes through the tungsten filament causes the release of copious amounts of electrons . tungsten has a high melting point and is electron rich therefore very suitable as a filament material. The cathode structure focuses the electrons into a beam that is accelerated by a potential diffenceat anode of thousands of volts until they strike the surface of the metal anode. The Xray tube is evacuated so that the air between the filament and the anode target don’t scatter electrons. The sides of the tubes is made of glass to allow the x-rays to pass through. The slight angling of the anode allows for wider dispersal of x-rays. Target should be material that withstands heat.When an electron hits the target in an X-ray tube, much of its energy is dissipated as heat. As the tube voltage increases however, the efficiency of the conversion of the energy of the electron beam to x-rays increases with energy of the incident electrons impinging on the target being dissipated as heat energy on the anode target. The efficiency of conversion is also directly proportional to the intensity of x-rays, tube current, and the atomic number of the target material with elements having a high atomic number like tungsten having the best conversion efficiency (IAEA, 1992, pg.As can be seen from the two graphs above, a change in tube voltage causes a change in the wavelength and the intensity of x-rays produced whereas no change in wavelength results in increasing the tube current. The energy of the X-rays produced by a tube depends upon the energy of the electrons striking the target. The energy of the striking electrons is controlled by the tube voltage and thus an increase in tube voltage results in the generation of more energetic/penetrating x-rays (shorter wavelength). On the other hand, an increase of tube current only increases the intensity of the X-ray produced but does not affect the energy of the x-rays produced (IAEA, 1992, pg.When a beam of x-rays falls on an object, it interacts with it such that some of it is transmitted through, some absorbed and some scattered in other directions. In simple scatter, the incident photon energy is much less than the binding energy of the electron in an atom. The photon is scattered without change of energy (Jerrold
ReferenceJerrold T. B., J. A. S., Edwin M. L., and John M. B, (2002). The Essential Physics of Medical Imaging. Wolters Kluwer Health.
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