Glossary

Sealed source: A radioactive source, sealed in an impervious container that has sufficient mechanical strength to prevent contact with and dispersion of the radioactive material under the conditions of use and wear for which it was designed. May be classified “Special Form” on shipping papers and packages.

Security: Prevention of theft, sabotage and other malevolent acts involving radiation sources.

Shielding: Any effective material between a radiation source and a potentially exposed person that reduces exposure.

SI: International System of Units, also known as the metric system.

Sievert (Sv): The sievert is a SI unit used to derive a quantity called dose equivalent or equivalent dose. This relates the absorbed dose in human tissue to the effective biological damage of the radiation. Not all radiation has the same biological effect, even for the same amount of absorbed dose. To determine equivalent dose (Sv), you multiply absorbed dose (Gy) by a quality factor (Q) that is unique to the type of incident radiation. One sievert (sv) is equivalent to 100rem.

Somatic health effects: The harm that an exposed individual suffers during their lifetime such as radiation induced cancer or sterility. Does not include later generation genetic effects.

Special Form Certificate: A certificate that confirms the manufacture and encapsulation of radioactive material into an impervious container. See: Sealed Source.

Special form radioactive material: Defined in 10 CFR Part 71 as radioactive material that exists as a single solid piece or is encapsulated material that meets certain other requirements.

Stable nucleus: The nucleus of an atom in which forces among its particles are balanced.

Stochastic effect: An effect regardless of dose that assumes there is always some small probability of adverse effects. The effect increases with dose. Cancer is a stochastic effect.

Survey meter: A device used to detect and measure the presence of ionizing radiation.