Sievert

Definition

A sievert (Sv) is the SI unit used to measure the biological effect of ionizing radiation on human tissue. It quantifies the risk of radiation exposure by accounting for the type and energy of radiation as well as its impact on different tissues.

5 Must Know Facts For Your Next Test

1. One sievert (Sv) represents a significant health risk, often associated with acute radiation sickness.
2. The sievert takes into account both the absorbed dose and the biological effectiveness of the radiation type.
3. Medical imaging procedures like X-rays and CT scans typically expose patients to millisieverts (mSv), which is one-thousandth of a sievert.
4. Radiation workers are usually limited to an annual exposure of 20 mSv according to international safety standards.
5. Effective dose in sieverts can be calculated using $E = \sum{H_{T} W_{T}}$, where $H_T$ is the equivalent dose to tissue T and $W_T$ is the tissue weighting factor.

Review Questions

• What does one sievert represent in terms of biological risk?
• How does a sievert differ from an absorbed dose measured in grays?
• What is the typical annual exposure limit for radiation workers?

Related terms

Gray (Gy): A gray is the SI unit that measures the absorbed dose of ionizing radiation, representing one joule per kilogram of tissue.

Equivalent Dose: The equivalent dose accounts for the type of radiation by using a weighting factor and is measured in sieverts.

Ionizing Radiation: Radiation that carries enough energy to liberate electrons from atoms or molecules, thereby ionizing them.