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Radiology part 1: x-ray

Radiology part 1: x-ray. Dr Haddadi, PhD, MSc Assistant prof. of Medical Physics Fassa University of Medical Sciences. Electromagnetic radiation. Any charge in motion induces magnetic field X-ray is a part of electromagnetic (EM) energy spectrum.

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Radiology part 1: x-ray

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  1. Radiologypart 1: x-ray Dr Haddadi, PhD, MSc Assistant prof. of Medical Physics Fassa University of Medical Sciences

  2. Electromagnetic radiation • Any charge in motion induces magnetic field • X-ray is a part of electromagnetic (EM) energy spectrum

  3. Photons are part of the electromagnetic spectrum Visible light Infrared X-rays & Gamma rays Radio UV Enough energy to cause ionization

  4. The Electromagnetic Spectrum

  5. EM properties • EM radiation propagates as a wave characterized by: - electric field - magnetic field - dielectric constant, and - electromagnetic properties of the medium • Wave length: distance of one complete cycle, λ, • Period: time for one cycle, T, and T=1/f Tc= λ and f λ=c c; 3 x 108 m/sec

  6. Sinusoidal EM wave • For a monochromatic radiation: - Magnetic and electric fields are functions of time, t, and space, x: Ф(x,t)= Ф0 cos(ωt – kx) Ф; electric field, ω=2πƒ; angular frequency, and k=2π/λ; for wave number • Ф(x,t) is a special form of the solution to the wave equation: c= (1/με)-1/2, μ is permeability of the medium and ε is permittivity of the medium

  7. EM properties cont’d • The main difference between X-ray and light or radio waves: frequency or wavelength (100-0.01 nm) • Dual characteristics of X-radiation: wave and particle interpretation of X- or gamma radiation Louis de Broglie equation (1924): λ = h/mv

  8. The wave concept to explain: • Phenomena: - reflection - scattering - refraction - diffraction

  9. Properties of X-Radiation as a particle: • Traveling at a speed of light; c • Carrying an energy given by; E=hfh;Planck constant (4.13 x 10-18 keV-sec, 1 ev= 1.6 x 10-19 joules) • These particles are called quanta, or photon • Photons are capable of ionizing atoms and molecules, so called ionizing radiation

  10. Classification of Indirectly IonizingPhoton Radiation Four distinct groups of photons ********** • Characteristic (fluorescent) x raysresult from electron transitions between atomic shells • Bremsstrahlungphotonsresult from electron-nucleus Coulomb interactions • Gamma raysresult from nuclear transitions • Annihilation quantaresult from positron-electron annihilation

  11. Characteristicx-ray

  12. Bremsstrahlungphotons

  13. Annihilation quanta

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