X-Rays

X-Ray Machine

X-radiations  is a form electromagnetic  radiation having   a wave length   ranging    from  0.01 to 10 nanometers, frequency ranging   between 30 petahertz to 30 exahertz,and  energies ranges between  100eV to 100KeV respectively .The  wave length of X-Rays are shorter than those of Ultraviolet rays and  longer than  that of  gamma rays.

Emission of X – Rays

X-Ray are emitted by electron and  gamma rays are emitted by the  nucleus, another way  to differentiate the  two is  on the basis  of  wave length   gamma rays  are of shorter wavelength  as compared to X-ray emitted from the  X-rays  tube is  of longer wave  length. Minimum amount of photon energy is emitted by electron/nucleus which is sufficient    enough to ionize the atom. The ionizing radiation which is released by the nucleus/electron is harmful to the living tissues.

Penetration of X- Rays

The depth of penetration depends upon the   magnitude over the X-Ray spectrum. The photons energy is adjusted in accordance to the application so that sufficient transmission can produce good contrast image. In malignacy high radiation doses are required for treatment due to this advantage the risk of harmful effects of radiations   can be outweighed.

Chest X-Ray

Types of X – Rays

  1. Hard X-rays: The photon energies above 5-10 keV and wave length between 9 -0.2-0.1nm wavelength) are called hard X-Rays. It has deep penetration power due to which it is used   in diagnosing and treating different diseases   in medicines and inspecting the luggage of passenger by Airport Security Personnel. In crystallography hard X-Ray can be used to determine the structure of crystal
  2. Soft X-Rays. The photons energies below 5 keV Soft X-ray can are absorbed in air.

Generation of X-Rays.

X-rays are emitted by electron and they are generated by  X-Ray tube  ,a vacuum tube  that uses  high voltage  to accelerate the  electron  released by the  cathode plate .The  high velocity electron collide with the anode and result in generation of  X-Rays. In Medicine the   target used in  X-Ray tube is usually tungsten or  more crack resistant  alloy of  5% rhenium and  95% tungsten and  some  time  metal molybendium for  more  specialized application in mammography. In crystallography, a copper target is the most commonly used.

X-Ray Fluorescence

The  inner electron  are  knocked down  from inner  electron shell results  in production of X-rays photon ,this  process produce  an emission of spectrum of  X-Rays of different frequencies  results in spectral line generation  and  depends upon the  targets (anode) element used and  thus  are called   characteristic line  ,the  transition from upper shell ( K shell )are  K Line  and  L shell are L line.

Voltage in Diagnostic X-Ray Tubes.

Voltage in X – Ray Tube ranges from20 to 150 KV and highest energies ranges from roughly 20vto 150 keV.  Most of the electric power produce by the tube is dissipated as waste heat.

Uses of X – Rays in Diagnosis and Treatment

  1. Projection (Plain) Radiography

Plain radiology was the only imaging modality which was used for diagnostic purpose in radiology for a period of 50 years of radiology. It is still presently used in evaluation of lungs, heart and skeleton, due speed and relatively of low cost it is commonly used. X-Ray tube  generate  a  bean  which is  transmitted  through  a patient  strike  the underdeveloped  film held  tight  to the  screen of  light  emitting  phosphors  in a light –tight cassette. The film is then developed chemically and an image appears on the film. Now film screen radiography has been replaced by Digital Radiography, in which the signals are generated into digital information system and an image on the computer screen.

  1. Fluoroscopy and  Angiography 

Fluoroscopy and  angiography are special applications  of  X-Ray imaging  ,in which a  fluorescent  screen and  image  intensifier tube  connected  to close circuit  television system. This  allow  real-time  imaging  of  structures in motion or  augmented  with  radio contrast agent .Radio contrast agents are  administered , often swallowed  or injected  into the body of  the  patient  ,to delineate  anatomy  and  functioning  of  blood  vessels, the genitourinary system or  gastrointestinal tract. Two radio contrasts are presently in use. Barium (as BaSO4) may be given orally or rectally for evaluation of GI tract. Iodine, in multiple proprietary forms, may be given orally, rectal, intra-arterial or intravenous routes. These radio contrast agents strongly absorb or scattered X-Ray radiation, in conjunction with the  real time  imaging  allow  demonstration of  dynamic  processes, such as peristalsis in the  digestive  tract  or  blood  flow in the  arteries  of  veins. Iodine  contrast  may  also be  used as  contrast  agent  in venous  system; in these cases the  contrast  agent  attenuates  the X-ray radiation  less than surrounding  tissues.

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