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E. 25 7. You are calculating the secondary barrier thickness in concrete for a linac vault with a max energy of 15 MV. Adjacent to the wall there is a fully occupied controlled area. You want to limit the dose to your workers to the declared pregnant worker dose limit. The workload is 1000 Gy/wk @1 m from iso do you mean target?. The wall is 4 m from iso. TVL for scattered radiation and leakage radiation and material used for shielding are 31 cm and 36 cm respectively. The equilibrium TVLe for scattered radiation in Pb is 4.7 cm. The densities of Pb and concrete are 11.35 gem and 2.35 gom-3 respectively. The equilibrium TVLe for leakage radiation is 33 cm. The max field size is 40x40 cm?. Assuming 0.1% for the scattering ratio for 400 cm field, wWhat is the required thickness of the wall? A. Leakage thickness + 1 HVL B. Scattered thickness + 1 HVL C. Leakage thickness only D. Scattered thickness only E. Scattered + Leakage thicknessWhat is the dose rate at 1m from a patient receiving external beam treatment? Orders of material from inside to outside