Stanza Radiografie-Barriere primarie in piombo con preschermatura

Figure excerpt from NCRP Report No. 147, Structural Shielding Design for Medical X-Ray Imaging Facilities

58-rad-lead pre

Fig. 4.5b. The lead thickness requirements for primary barriers assuming preshielding (xpre) in the representative radiographic room as a function of NT/Pd2 (see Section for caveats on xpre). P is in milligray per week, N is the weekly total number of patients examined in the radiographic room, and d (in meters) is chosen as the distance from most intense radiation source to the occupied area. The chest-bucky wall and floor are assumed primary barriers with a cassette, grid, and supporting structures present. The cross-table lateral wall and wall with two percent use factor assume the presence of just a cassette and grid. If the Wnorm values given in Table 4.5 do not match the per patient workload for the facility under consideration, then the original value of NT/Pd2 can be multiplied by Wsite / Wnorm, and the modified value can be used to obtain the required shielding from Figure 4.5b.