Absorption of X-Rays

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Absorption of X-Rays

Absorption of X-rays is analogous to that of gamma radiation. The absorption follows an exponential pattern.

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Half thickness

  • A 'half thickness' can be quoted for the thickness of material required to reduce the intensity of an X-ray beam by a half.
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Intensity of x-ray radiation

  • So:
    • I=I0eμxI = I_0 e^{-μx}
      • I and I0 are the final and original intensities.
      • μ is the linear (absorption) coefficient.
      • x is the thickness of the material being penetrated.
  • The density of the absorbing material is a major factor in the value of μ, so that regions of similar material of different density will absorb at different rates.
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Mass attenuation coefficient

  • Mass attenuation coefficient =μρ= \frac{μ}{ρ}
    • ρ is the density of the material.
  • Examples are:
    • Lung tissue = 6 cm²/g
    • Breast tissue = 4 cm²/g
      • These values are true at a photon energy of 10 keV.

Jump to other topics

1Measurements & Errors

2Particles & Radiation


4Mechanics & Materials


6Further Mechanics & Thermal Physics (A2 only)

7Fields & Their Consequences (A2 only)

8Nuclear Physics (A2 only)

9Option: Astrophysics (A2 only)

10Option: Medical Physics (A2 only)

11Option: Engineering Physics (A2 only)

12Option: Turning Points in Physics (A2 only)

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