This chapter provides a comprehensive understanding of the fundamental principles, practices, and regulations essential for ensuring radiation protection in diagnostic radiology and related medical practices. Beginning with the core framework i.e. justification, optimization, and dose limitation. It further explains key radiation protection strategies involving time, distance, and shielding, supported by practical approaches for dose monitoring and record keeping. A detailed section defines and distinguishes important radiation dose terms such as absorbed dose, equivalent dose, effective dose, and collective dose. The chapter outlines internationally accepted dose limits for patients, comforters, biomedical research volunteers, and occupational exposure, while also emphasizing the use of diagnostic reference levels (DRLs) and dose constraints to maintain safe practices. Historical context and evolving recommendations on dose limits are also discussed in detail. Further, the chapter highlights safe work practices, including the use of physical barriers, protective devices, and shielding techniques. An overview of global and national regulatory and advisory bodies such as the ICRP, IAEA, WHO, UNSCEAR, and national authorities and explains their role in policy formation and implementation. The biological effects of radiation including deterministic and stochastic effects, with a specialized focus on female patients, radiation workers, and fetal safety during pregnancy. Specific protocols for informed consent and diagnostic decision-making during pregnancy are addressed to ensure maternal and fetal protection. It tries to answer all apprehensive questions of a pregnant radiation worker. Further, the chapter discusses radiation areas (controlled, supervised, and unsupervised) and gives details of various personal monitoring devices, including thermoluminescent dosimeters (TLDs), Optically Stimulated Luminescence (OSL) dosimeters, ionization chambers, film badges, and extremity monitors. Finally, it addresses preparedness and response strategies for radiation emergencies, covering scenarios such as accidental exposures, and radiological threats etc.