X-ray Scattering in the Shielding of Industrial Irradiation Facilities

When high-energy X-ray photons impinge on thick shields, most of the incident energy is absorbed in the shielding material, but some of it is deflected sideways or backward into the treatment room. This effect is important in facilities that have openings in the shields to allow the passage of products through the irradiation zone or mazes to provide access into this zone for operating personnel. Multiple scattering events in these openings can reduce the energies of the photons and the dose rates of the residual radiation to comply with applicable safety regulations. Basic equations and examples are presented to show how these scattering effects can be evaluated in the designs of new irradiation facilities.