Which unit is commonly used to express the biological effects of radiation?

The Sievert is the unit most commonly used to express the biological effects of radiation. It quantifies the health effect of ionizing radiation on the human body by considering not just the amount of radiation absorbed (which is measured in Grays) but also the biological impact based on the type of radiation and the tissue being affected.

Different types of radiation have different levels of biological effectiveness, and the Sievert accounts for these variations through a quality factor. For instance, alpha particles are more biologically damaging than beta particles or gamma rays when considered at the same absorbed dose. Therefore, using the Sievert allows healthcare professionals and researchers to assess risk and make informed decisions about safety standards, employee monitoring, and patient treatment in radiation environments.

In contrast, other units like the Roentgen and Curie measure different aspects of radiation. The Roentgen measures ionization in air produced by X-rays or gamma rays but does not provide a direct assessment of biological effects. The Gray measures the absorbed dose of radiation but lacks the biological weighting needed for risk assessment in health contexts. The Curie is a measure of radioactivity, indicating the number of decays per second, but it does not relate directly to biological effects. Hence, the Sievert is the most