Numerical models for the determination of primary structural barriers for diagnostic x-ray facilities

In this work, numerical models are presented for the determination of additional shielding requirements apart from that afforded by patient and hardware devices (grid, cassette, cassette holder, and x-ray table) for diagnostic x-ray primary beams. The models provide an opportunity for the incorporation of appropriate transmission factors obtained by integration of incident radiation energy distribution and workload spectra for clinically realistic condition of varying thicknesses of patient. It was found that as a result of significant differences in the attenuation and hardening properties of water (which was used to represent patient) and lead, lead exposure attenuation equivalent thicknesses do not transmit beam of equivalent penetrating power (though of equivalent exposure) as corresponding patient thicknesses. Sample results are presented which show that ignoring these significant differences will result in underestimation of shielding afforded by patient and hardware devices in practice; thus installing in addition more thickness of lead than necessary. For different incident beam qualities (kVp), obtaining exposure attenuation equivalence of varying thicknesses of patients and hardware in terms of lead is a nontrivial phenomenon.