What is the approximate relative risk from exposure to radiation measured in?

The approximate relative risk from exposure to radiation is measured in Sieverts or rem. These units quantify the biological effects of ionizing radiation, particularly in terms of how much harm it can potentially cause to human tissues. The Sievert (Sv) is the SI (International System of Units) unit of measure for the biological effect of radiation, while the rem (roentgen equivalent man) is an older unit that has largely been replaced by the Sievert but is still sometimes used.

This measurement is essential in fields such as diagnostic imaging and radiation therapy because it helps healthcare professionals assess the potential risks to patients and make informed decisions regarding radiation exposure. It accounts for the type of radiation and its impact on living tissue, providing a clearer understanding of safety and risk associated with radiation use in medical settings.

Other units like Gray or rad are focused more on the physical measurement of radiation dose rather than the biological effect, while Becquerel or curie measures radioactivity, and Watt or joule relate to energy, rather than radiation's effects on health. Thus, Sieverts or rem specifically address the concern of risk from radiation exposure.