What is the primary measure for dose equivalent, denoted as H?

The primary measure for dose equivalent, denoted as H, is the Sievert. The Sievert is a unit that quantifies the biological effect of ionizing radiation on human health, incorporating both the absorbed dose and the type of radiation involved. This measure is important because not all types of radiation produce the same biological effect despite depositing the same amount of energy. By using the Sievert, medical professionals can better assess risk and determine appropriate safety measures when dealing with radiation exposure.

In contrast, the other units listed, such as Rad and Gray, measure the absorbed dose of radiation, which focuses purely on the amount of energy deposited in tissue without accounting for biological effects. The Rem is an older unit that also represents dose equivalent and is still used in some contexts, but it is less common than the Sievert in modern practice. The Sievert is the standard unit utilized worldwide, making it the preferred choice for evaluating the protective measures against radiation exposure in medical settings.