What is the SI unit of dose equivalent for ionizing radiation?

The SI unit of dose equivalent for ionizing radiation is the sievert. The sievert is used to measure the health effects of ionizing radiation on the human body. It accounts for the type of radiation and its biological impact, which distinguishes it from the gray, which measures the absorbed dose of radiation without considering its biological effects.

The concept of dose equivalent allows for the assessment of potential biological damage caused by different types of radiation, such as alpha particles, beta particles, gamma rays, and x-rays, reflecting their varying degrees of harm. This makes the sievert particularly important in fields like radiation protection and radiology, where understanding the impact of different radiation exposures is crucial for safety and risk assessment.

In this context, the rad and the roentgen are older units of measurement; the rad has been largely replaced by the gray, and the roentgen is specific to exposure from gamma and x-rays, lacking a direct correlation to biological effects. Therefore, the sievert is the correct and most relevant unit when discussing the dose equivalent of radiation.