Glossary of Radiological Terminology (S)

GLOSSARY OF
RADIOLOGICAL TERMINOLOGY

SCATTERED RADIATION Radiation that, during its passage through a material, has been changed in direction.
SCINTILLATION CAMERA A device used for visualizing the spatial distribution of a radionuclide within an organ or gland in the body. The gamma camera uses a stationary NaI(Tl) crystal as the detection element.
SCINTILLATION COUNTER A counter in which light flashes produced in a scintillator by ionizing radiation are converted into electrical pulses by a photomultiplier tube.
SEALED SOURCE Radioactive material that is permanently bonded or fixed in a capsule or matrix designed to prevent release and dispersal of the radioactive material under the most severe conditions.
SHALLOW DOSE EQUIVALENT The external exposure of the skin or an extremity and is the dose equivalent at a tissue depth of 0.007 centimeter (7 mg/cm squared) averageed over an area of one square centimeter.
SHIELDING MATERIAL Any material which is used to absorb radiation and effectively reduce the radiation intensity and in some cases, eliminate it. Lead, concrete, aluminum, water, paraffin and plastic are examples of commonly used shielding materials.
SIEVERT The System International (SI) unit of dose equivalent equal to 100 rem. It is obtained by multiplying the number of grays (Gy) by the quality factor, distribution factor, and any other necessary modifying factors.
SOMATIC EFFECTS OF RADIATION Effects of radiation limited to the exposed individual, as distinguished from genetic effects, which may also affect subsequent unexposed generations.
SOURCE MATERIAL Uranium or thorium in any combination of uranium and thorium in any physical or chemical form; or, ores that contain by weight, one-twentieth of 1 percent (0.05%) or more of uranium, thorium, or any combination of uranium and thorium. Source material does not include special nuclear material.
SPECIAL NUCLEAR MATERIAL Plutonium, uranium-233, uranium-235 and any other material that the Nuclear Regulatory Commission determines to be special nuclear material, but does not include source material; or any material artificially enriched by any of the foregoing.
SPECIFIC ACTIVITY The total activity of a given nuclide per gram of a compound, element or radioactive nuclide.
SPECIFIC GAMMA-RAY CONSTANT The gamma exposure rate in R/hr at 1 centimeter from a 1 mCi source.
STABLE ISOTOPE An isotope that does not undergo radioactive decay.
STOCHASTIC EFFECTS Health effects that occur randomly and for which the probability of the effect occurring, rather than its severity, is assumed to be a linear function of dose without threshold. Hereditary effects and cancer incidence are examples of stochastic effects.
SURVEY METER Any portable radiation detection device used for inspecting an area to determine the existence and amount of radioactive material present. May also be used to determine radiation levels.

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SCATTERED RADIATION	Radiation that, during its passage through a material, has been changed in direction.
SCINTILLATION CAMERA	A device used for visualizing the spatial distribution of a radionuclide within an organ or gland in the body. The gamma camera uses a stationary NaI(Tl) crystal as the detection element.
SCINTILLATION COUNTER	A counter in which light flashes produced in a scintillator by ionizing radiation are converted into electrical pulses by a photomultiplier tube.
SEALED SOURCE	Radioactive material that is permanently bonded or fixed in a capsule or matrix designed to prevent release and dispersal of the radioactive material under the most severe conditions.
SHALLOW DOSE EQUIVALENT	The external exposure of the skin or an extremity and is the dose equivalent at a tissue depth of 0.007 centimeter (7 mg/cm squared) averageed over an area of one square centimeter.
SHIELDING MATERIAL	Any material which is used to absorb radiation and effectively reduce the radiation intensity and in some cases, eliminate it. Lead, concrete, aluminum, water, paraffin and plastic are examples of commonly used shielding materials.
SIEVERT	The System International (SI) unit of dose equivalent equal to 100 rem. It is obtained by multiplying the number of grays (Gy) by the quality factor, distribution factor, and any other necessary modifying factors.
SOMATIC EFFECTS OF RADIATION	Effects of radiation limited to the exposed individual, as distinguished from genetic effects, which may also affect subsequent unexposed generations.
SOURCE MATERIAL	Uranium or thorium in any combination of uranium and thorium in any physical or chemical form; or, ores that contain by weight, one-twentieth of 1 percent (0.05%) or more of uranium, thorium, or any combination of uranium and thorium. Source material does not include special nuclear material.
SPECIAL NUCLEAR MATERIAL	Plutonium, uranium-233, uranium-235 and any other material that the Nuclear Regulatory Commission determines to be special nuclear material, but does not include source material; or any material artificially enriched by any of the foregoing.
SPECIFIC ACTIVITY	The total activity of a given nuclide per gram of a compound, element or radioactive nuclide.
SPECIFIC GAMMA-RAY CONSTANT	The gamma exposure rate in R/hr at 1 centimeter from a 1 mCi source.
STABLE ISOTOPE	An isotope that does not undergo radioactive decay.
STOCHASTIC EFFECTS	Health effects that occur randomly and for which the probability of the effect occurring, rather than its severity, is assumed to be a linear function of dose without threshold. Hereditary effects and cancer incidence are examples of stochastic effects.
SURVEY METER	Any portable radiation detection device used for inspecting an area to determine the existence and amount of radioactive material present. May also be used to determine radiation levels.