One of radiologic technologists' most important professional obligations is protecting patients, other members of the health care team, the public and themselves from as much radiation-related harm as possible while also maximizing the screening, diagnostic and therapeutic potential of ionizing radiation. This article reviews the different types of radiation dose and how radiation affects the body. Patient shielding, personnel dosimeters and area monitors are discussed, along with beam collimation and filtration. The author also describes protocols to protect pregnant patients and pregnant technologists.