A series of nomograms that simplify determination of diagnostic X-ray shielding requirements with lead are presented. All recommendations of the NCRP, except that to "add one half value layer" in determining secondary barriers, were followed in the production of these curves. For secondary barriers, the shielding required to reduce the weekly exposure to the applicable MPD has been determined. This eliminates the over-shielding inherent in the "add one HVL" approximation and allows a variety of more cost effective materials to be considered for secondary barriers.

Reference values (RVs) are recommended by the American Association of Physicists in Medicine for four radiographic projections, computed tomography, fluoroscopy, and dental radiography. RVs are used to compare radiation doses from individual pieces of radiographic equipment with doses from similar equipment assessed in national surveys. RVs recommended by the American Association of Physicists in Medicine have been developed from the Nationwide Evaluation of X-ray Trends survey performed by the state radiation protection agencies with the cooperation and support of the U.S. Food and Drug Administration, the Conference of Radiation Control Program Directors, and the American College of Radiology. The RVs selected by the American Association of Physicists in Medicine represent, approximately, the 80th percentile of the survey distributions. Consequently, equipment exceeding the RVs is using higher radiation doses than is 80% of the equipment in the surveys. Radiation doses for specific projections, with standard phantoms, should be measured annually, as recommended by the American College of Radiology. When the RVs are exceeded, the medical physicist should investigate the cause and determine, in cooperation with the responsible radiologist, whether these doses are justified or the imaging system should be optimized to reduce patient radiation doses. RVs are a useful tool for comparing patient radiation doses at institutions throughout the United States and for providing information about radiographic equipment performance.

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Single- and three-phase broad-beam x-ray attenuation data have been obtained using lead, steel, plate glass, gypsum wallboard, lead acrylic, and wood. Tube voltages of 50, 70, 100, 125, and 150 kVp were employed and the resulting curves were compared to transmission data found in the literature. To simplify computation of barrier requirements, all data sets were parametrized by nonlinear least-squares fit to a previously described mathematical model. High attenuation half value layers and the lead equivalence of the alternate materials were also determined.

A four-parameter Laplace transform pair model, which accurately reconstructs an experimental bremsstrahlung spectrum from attenuation data, is presented. Computed spectral values with both aluminum and copper attenuators generally agree with experimental 70-kVp data to better than 2%. Reconstructed spectra at other kVp's also show good agreement with published data.