Importance Of CT Scanner
1-The x-ray tube and detector transverse (scan) the object.
2-The radiation beam passes through the object and is attenuated. The intensity of radiation beam from x- ray tube and transmitted beam both are detected by suitable detectors.
3-The transmitted beam and the references beam are both converted into electric signals.
4-These output current signals are then converted into digital form by analog –to-digital converter.
5-The digital data are then normalized and the logarithms calculated to generate relative transmission values :
Relative transmission values =log I0/I.
6-The relative transmission values are sent to the computer, which uses suitable programs to reconstruct cross sections …show more content…
X-ray is an electromagnetic waveform, with a wavelength ranging from few Pico-meters to a few nanometers, with its photon energy being proportional to its frequency (Ε = hν = hc/λ). Therefore, making X-rays with shorter wavelength possess a higher energy than longer wavelengths. . X-ray photons are produced when high-speed electrons bombard a substance, as it interacts with the target, having different types of collisions. Small energy transfers from a high-speed electron to electrons that are knocked out of the atoms in the majority of these encounters. Leading to ionization of the object atoms, this type of interaction does not produce x-rays, but gives rise to delta rays and eventually heat. For a standard x-ray tube, over 99% of the input energy is converted to heat. (Hsieh, 2009). The X-ray structure consists of an x-ray generator, x-ray tube, x-ray beam filter, and …show more content…
As an x-ray beam penetrates through the examined object/patient to be examined, and be attenuated at varying extents; each local absorbtion then would measured with the detector array. (In a special CT acquisition protocol, the spiral measurement process, the X-ray tube is continuously rotated, with the examination table being moved lin- early through the measuring field. This scan process produces data that take a spi- ral or helical path. This method offers the possibility of computing any number of slices retrospectively, so that an accurate three-dimensional rendering can be ex- pected. To allow this acquisition technique, a slip ring transfer system has been de- veloped. In such a system, power supply to the X-ray tube and signal transfer from the detector system is guaranteed, even though the imaging system continuously