Linear attenuation coefficent (µ) is a constant that describes the the fraction of attenuated incident photons in a monoenergetic beam per unit thickness of a material. Its complement is the transmitted portion of the beam. It is expressed numerically in units of cm-1.
The intensity of the beam at distance x (cm) within a material is calculated using the following equation 1:
Where Ix is the intensity at depth of x cm, I0 is the original intensity, and µ is the linear attenuation coefficient.
Rearrange and take the log of both sides gives the equation for µ.
μ = ln(Io/Ix)/x
- 1. The AAPM/RSNA physics tutorial for residents. X-ray attenuation. (1998) RadioGraphics. 18 (1): 151-63; quiz 149. doi:10.1148/radiographics.18.1.9460114 - Pubmed
- 2. Bushberg JT, Seibert JA, Jr. EML et-al. The Essential Physics of Medical Imaging. LWW. ISBN:0781780578. Read it at Google Books - Find it at Amazon