Attenuation Calculation The linear attenuation coefficient (m) describes the fraction of a beam of xrays or gamma rays that is absorbed or scattered per unit thickness of the absorber. m basically accounts for the number of atoms in a cubic cm volume of material and the probability of a photon being scattered or absorbed from the nucleolus or an electron of one of these atoms. m is used in the following equation to calculate the intensity of a narrow beam of penetrating radiation after it has traveled a given distance in a material.
Where: 
I_{x} 
= 
the intensity of photons transmitted across some distance x 

I_{0} 
= 
the initial intensity of photons 

m 
= 
the linear attenuation coefficient 

x 
= 
distance traveled 
Using the transmitted intensity equation above, linear attenuation coefficients can be used to make a number of calculations. These include:
 the intensity of the energy transmitted through a material when the incident xray intensity, the material and the material thickness are known.
 the intensity of the incident xray energy when the transmitted xray intensity, material, and material thickness are known.
 the thickness of the material when the incident and transmitted intensity, and the material are known.
 and the material can be determined be determined from the value of m when the incident and transmitted intensity, and the material thickness are known.
