When X-rays or gamma rays are directed into an
object, some of the photons interact with the
particles of the matter and their energy can be
absorbed or scattered. This absorption and
scattering is called “Attenuation”. Other photons
travel completely through the object without
interacting with any of the material's particles. The
number of photons transmitted through a material
depends on the thickness, density and atomic
number of the material, and the energy of the
individual photons.