This document discusses concepts related to radiation shielding, including: - How radiation intensity decreases with distance from the source according to the inverse square law. Fluence and flux are defined to describe radiation intensity. - Formulas are provided to calculate flux and exposure rate at varying distances from a point source, taking into account the source strength, photon energy, and attenuation from any shielding material. - Tables of attenuation coefficients are given for various materials to allow for calculations of exposure rate from shielded sources. - Simplified rules of thumb are described for estimating exposure rates from gamma and beta point sources based on source strength, photon energy, and distance from the source.