DHS 157.03(337)(337) “Shutter” means a device attached to the tube housing assembly which may totally intercept the useful beam and which has a lead equivalency not less than that of the tube housing assembly.

DHS 157.03(338)(338) “Sievert” or “Sv” means the SI unit of dose equivalent. The unit of dose equivalent is the joule per kilogram. The special unit of dose equivalent (rem) is being replaced by the sievert. 1 Sv=100 rem.

DHS 157.03(339)(339) “Single tomogram system” means a CT x-ray system which obtains x-ray transmission data during a scan to produce a single tomogram.

DHS 157.03(340)(340) “Site area emergency” means an event may occur, is in progress, or has occurred that could lead to a significant release of radioactive material and require a response by offsite response organizations to protect people offsite.

DHS 157.03(341)(341) “Site boundary” means that line beyond which the land or property is not owned, leased or otherwise controlled by the licensee or registrant.

DHS 157.03(342)(342) “Source” means the region and material from which the radiation emanates.

DHS 157.03(343)(343) “Source applicator” means a device used to place a radioactive source in a precise anatomical location within the body.

DHS 157.03(344)(344) “Source assembly” means an assembly that consists of the sealed source and a connector that attaches the source to the control cable. The source assembly may include a ballstop to secure the source in the shielded position.

DHS 157.03(345)(345) “Source changer” means a device designed and used for replacement of sealed sources in radiographic exposure devices and which may also be used for transporting and storing sealed sources.

DHS 157.03(346)(346) “Source holder” means a housing or assembly into which a radioactive source is placed to facilitate the handling and use of the source in well logging operations.

DHS 157.03(347)(347) “Source-image receptor distance” or “SID” means the distance from the source of radiation to the center of the input surface of the image receptor.

DHS 157.03(348)(348) “Source material” means either of the following:

DHS 157.03(348)(b)(b) Ores that contain by weight one-twentieth of one percent or more of uranium, thorium or any combination of uranium and thorium. Source material does not include special nuclear material.

DHS 157.03(349)(349) “Special form radioactive material” means radioactive material that satisfies all the following conditions:

DHS 157.03(349)(a)(a) It is either a single solid piece or is contained in a sealed capsule that may be opened only by destroying the capsule.

DHS 157.03(349)(c)(c) It satisfies the test requirements specified by the NRC in 10 CFR 71.75 at the time of its design or construction.

DHS 157.03(350)(350) “Special nuclear material” means plutonium, uranium 233, uranium enriched in the isotope 233 or in the isotope 235, and any other material which the nuclear regulatory commission determines to be special nuclear material; or any material artificially enriched by any of the foregoing. Special nuclear material does not include source material.

DHS 157.03(351)(351) “Special nuclear material in quantities not sufficient to form a critical mass” means uranium enriched in the isotope U-235 in quantities not exceeding 350 grams of contained U-235; uranium-233 in quantities not exceeding 200 grams; plutonium in quantities not exceeding 200 grams; or any combination of them under the following formula: For each kind of special nuclear material, determine the ratio between the quantity of that special nuclear material and the quantity specified above for the same kind of special nuclear material. The sum of such ratios for all of the kinds of special nuclear material in combination may not exceed one.

DHS 157.03 NoteNote: For example, the following quantities in combination would not exceed the limitation and are within the formula:

DHS 157.03(352)(352) “Special unit” means the alternative system of units for quantifying absorbed dose in rad, dose equivalent in rem and radioactivity in curie.

DHS 157.03(353)(353) “Specific activity” of a radionuclide means the radioactivity of the radionuclide per unit mass of that nuclide. The specific activity of a material in which the radionuclide is essentially uniformly distributed is the radioactivity per unit mass of the material.

DHS 157.03(354)(354) “Specific license” means a license, under requirements prescribed by the department by rule, to possess, use, manufacture, produce, transfer or acquire radioactive material or devices or equipment utilizing radioactive material.

DHS 157.03(355)(355) “Spot film” means a radiograph, which is made during a fluoroscopic examination to permanently record conditions that exist during that fluoroscopic procedure.

DHS 157.03(356)(356) “Spot-film device” means a device intended to transport and position a radiographic image receptor between an x-ray source and fluoroscopic image receptor. It includes a device intended to hold a cassette over the input end of an image intensifier for the purpose of making a radiograph.

DHS 157.03(357)(357) “Stationary beam radiation therapy” means radiation therapy without displacement of one or more mechanical axes relative to the patient during irradiation.