This chapter explains about the methods by which the radiation exposure to a person can be minimized (Time, Distance, Shielding and Contamination control), definitions for HVL, TVL and relationship between them. It also includes the sources of exposure and the leakage limits for diagnostic X-ray tube housing, Co-60 Teletherapy and Brachytherapy. This chapter also gives definitions of workload, user factor, occupancy factor and calculation of workload for different facilities. The last part explains about the protective barrier design and calculation of primary and secondary barrier thickness for Diagnostic X-ray unit, CT, Nuclear Medicine and Radiotherapy and Brachytherapy with examples.