Welcome back to the RadOnc Smart Review Physics Series! We've explored how radiation is produced, how it interacts, how we measure it, plan treatments, and ensure quality. Now, we circle back to a fundamental responsibility: radiation safety. In Episode P16a: Radiation Protection & Regulations, we'll review the types of radiation effects, the quantities used to measure risk (Dose Equivalent, Effective Dose), the ALARA principle, the critical regulatory dose limits for workers and the public, and touch upon managing dose from internal radioactivity.