What is the SI equivalent of the rem?

The correct answer is the sievert, which is the SI (International System of Units) unit used to measure biological effect of ionizing radiation. The sievert accounts for the type of radiation and its impact on human health, making it a critical unit in radiological protection. It is defined in terms of the dose in grays (the SI unit for absorbed radiation dose) adjusted for the biological effect throughput a quality factor. This makes it more applicable to understanding the health risks associated with radiation exposure compared to other units.

The rem, which is an older non-SI unit, was used to express the same idea before the adoption of the sievert. One simple conversion is that 1 sievert is equal to 100 rems, which highlights the transition from older measurement practices to standardized SI units in radiation safety and evaluation.

The other units mentioned serve different purposes: the rad measures absorbed dose but does not account for biological effects, the gray is an SI unit for absorbed dose similar to the rad, and the roentgen measures exposure to ionizing radiation in air, but again does not relate directly to biological effect as the sievert does. Understanding these distinctions is pivotal for professionals in the field of dental radiography and radiation safety.