Concerning the interaction of X-ray photons with matter:
It is possible to predict the fraction of photons that will be absorbed or scattered, when passing through a given material
Attenuation is represented by the number of photons absorbed or scattered by matter
Scattered photons help form the primary image on the film
The half-value layer (HVL) of a material is the thickness needed to reduce the number of photons in a beam by half
The HVL is inversely proportional to the linear attenuation coefficient (LAC) of a material
