## Attenuation of X - Rays

\[I_0\]

and the intensity of the X - Rays at a depth \[x\]

is \[I\]

, then\[I=I_0 e^{- \mu x}\]

where

\[\mu\]

is the linear coefficient, different for different tissues.The relationship implies that a constant fraction of the X - Ray intensity is absorbed per unit length of penetration of the X - Rays into the tissue. The attenuation coefficient is due to the interaction of X rays with the electrons surrounding atoms. Heavier atoms have more electrons so a higher attenuation coefficient. The attenuation coefficient varies roughly as the cube of the atomic number.