CAMRT Radiography Practice Exam

Which of the following units is categorized as an SI Unit?

1. Rad

2. Roentgen

3. Sievert

4. Rem

The correct answer is: Sievert

The Sievert is categorized as an SI Unit because it is the standard unit of measurement in the International System of Units (SI) for the biological effects of ionizing radiation. It quantifies the impact of radiation on human health and takes into account the relative biological effectiveness of different types of radiation. This is crucial in radiography as it helps in assessing the potential risks associated with radiation exposure. In contrast, the other listed units—Rad, Roentgen, and Rem—are older units that are not part of the SI system. The Rad measures absorbed dose, the Roentgen measures exposure to ionizing radiation, and the Rem quantifies dose equivalent, which also accounts for biological effects but has been largely replaced by the Sievert in modern practice. The transition to SI units such as the Sievert reflects efforts to standardize measurements internationally, facilitating clearer communication and understanding of radiation safety and exposure.