DHS 157.03(103m)(103m) “DICOM” means digital imaging and communications in medicine. DHS 157.03(103r)(103r) “Discrete source” means a radionuclide that has been processed so that its concentration within a material has been purposely increased for use for commercial, medical, or research activities. DHS 157.03(104)(104) “Disposable respirator” means a respirator for which maintenance is not intended and that is designed to be discarded after excessive breathing resistance, sorbent exhaustion, physical damage, or end-of-service-life renders it unsuitable for use. Examples of this type of respirator are a disposable half-mask respirator or a disposable escape-only self-contained breathing apparatus. DHS 157.03 NoteNote: Sorbent exhaustion refers to the inability of an absorbent material to absorb any more of the material for which it was designed.
DHS 157.03(105)(105) “Disposal” means the isolation of radioactive wastes from the environment inhabited by man and containing his food-chains by emplacement in a land disposal facility. DHS 157.03(106)(106) “Disposal site” means that portion of a land disposal facility which is used for the disposal of waste. It consists of disposal units and a buffer zone. DHS 157.03(107)(107) “Disposal unit” means a discrete portion of a disposal site into which waste is placed for disposal. DHS 157.03(108)(108) “Distinguishable from background” means that the detectable concentration of a radionuclide is statistically different from the background concentration of that radionuclide in the vicinity of that site or, in the case of structures, in similar materials using adequate measurement technology, survey and statistical techniques. DHS 157.03(108m)(108m) “Diversion” means the unauthorized movement of category 1 or category 2 quantity of radioactive material that is subject to subch. XV to a location different from the material’s authorized destination inside or outside of the site at which the material is used or stored. DHS 157.03(109)(109) “Dose equivalent” or “HT” means the product of the absorbed dose in tissue, quality factor and all other necessary modifying factors at the location of interest. The units of dose equivalent are the sievert and rem. DHS 157.03(109m)(109m) “Dose length product” or “DLP” means the metric which is related to the total energy imparted in the patient, and is determined by multiplying the CTDIvol value by the scan length, resulting in the units of mGy-cm. DLP is calculated using the following formula: where:
L = the length of patient scanned.
p = is the pitch.
CTDI100,cent = CTDI100 value determined at the center of a standardized phantom.
CTDI100,periphery = CTDI100 value determined at the periphery of a standardized phantom.
DHS 157.03(110)(110) “Dose limits” means the permissible upper bounds of radiation doses established under this chapter. DHS 157.03(111)(111) “Dose monitor unit” means a unit response from the beam monitoring system from which the absorbed dose may be calculated. DHS 157.03(112)(112) “Dose profile” means the dose as a function of position along a line. DHS 157.03(113)(113) “Dosimeter” means a recording device used to measure exposure to ionizing radiation. DHS 157.03(114)(114) “Dosimetry processor” means an individual or an organization that processes and evaluates individual monitoring devices to determine the radiation dose delivered to the monitoring devices. DHS 157.03(115)(115) “Doubly encapsulated sealed source” means a sealed source in which the radioactive material is sealed within an inner capsule and that capsule is sealed within an outer capsule. DHS 157.03(116)(116) “Effective dose equivalent” or “EDE” means the sum of the products of the dose equivalent to each organ or tissue and the weighting factor applicable to each of the body organs or tissues that are irradiated (HE = å wTHT). DHS 157.03 NoteNote: Effective dose equivalent (HE) equals the sum of the weighting factor (wT) times the dose equivalent to each organ or tissue (HT).
DHS 157.03(117)(117) “Electron microscope” means a microscope utilizing electrons to provide high magnification examination of materials. DHS 157.03(118)(118) “Elemental area” means the smallest area within a tomogram for which the x-ray attenuation properties of a body are depicted. DHS 157.03(119)(119) “Embryo or fetus” means the developing human organism from conception until the time of birth. DHS 157.03(120)(120) “Emergency” means an event requiring prompt action to mitigate a threat to the health and safety of workers and the public or a threat of damage to the environment. DHS 157.03(121)(121) “Energy compensation source” or “ECS” means a small sealed source, with an activity not exceeding 3.7 MBq (100 microcuries), used within a well logging tool, or other tool components, to provide a reference standard to maintain the well logging tool’s calibration when in use. DHS 157.03(122)(122) “Enriched uranium” means uranium containing more uranium-235 than the naturally occurring distribution of uranium isotopes. DHS 157.03(123)(123) “Entrance air kerma rate” means the air kerma free in air per unit time at the point where the center of the useful beam enters the patient. DHS 157.03(124)(124) “Entrance or access point” means any location through which an individual could gain access to radiation areas or to licensed or registered radioactive materials. This includes entry or exit portals of sufficient size to permit human entry, irrespective of their intended use. DHS 157.03(124g)(124g) “Escorted access” means the continuous direct visual surveillance by an approved individual over an individual in the security zone who is not approved for unescorted access. DHS 157.03(124m)(124m) “Exclusive use” means the sole use by a single consignor of a conveyance for which all initial, intermediate, and final loading and unloading are carried out in accordance with the direction of the consignor or consignee. The consignor and the carrier must ensure that any loading or unloading is performed by personnel having radiological training and resources appropriate for the safe handling of the consignment. The consignor shall issue specific instructions, in writing, for maintenance of exclusive use shipment controls, and include them with the shipping paper information provided to the carrier by the consignor. DHS 157.03(125)(125) “Explosive material” means any chemical compound, mixture or device that produces a substantial instantaneous release of gas and heat spontaneously or by contact with sparks or flame. DHS 157.03(126)(126) “Exposure” means the quotient of dQ divided by dm where “dQ” is the absolute value of the total charge of the ions of one sign produced in air when all the electrons liberated by photons in a volume element of air having mass “dm” are completely stopped in air. The SI unit of exposure is the coulomb per kilogram. The standard unit of exposure is the roentgen. DHS 157.03(127)(127) “Exposure head” means a device that locates the gamma radiography sealed source in the selected working position. DHS 157.03(128)(128) “Exposure rate” means the exposure per unit of time, such as roentgen per minute and milliroentgen per hour. DHS 157.03(129)(129) “External beam radiation therapy” means therapeutic irradiation in which the source of radiation is at a distance from the body. DHS 157.03(130)(130) “External dose” means that portion of the dose equivalent received from any source of radiation outside the body. DHS 157.03(131)(131) “External sinking fund” means an account, segregated from licensee assets and outside the licensee’s administrative control, into which monies are periodically deposited that are sufficient to pay decommissioning costs expected at the time licensee operations are terminated. DHS 157.03(132)(132) “Extremity” means hand, elbow, arm below the elbow, foot, knee and leg below the knee. DHS 157.03(133)(133) “Extremity bone densitometer” means a device that tests the mineral content of the bone of the fore arm, hand or foot. DHS 157.03(135)(135) “Field emission equipment” means equipment that uses an x-ray tube in which electron emission from the cathode is due solely to the action of an electric field. DHS 157.03(136)(136) “Field station” means a facility where radioactive sources may be stored or used and from which equipment is dispatched to temporary job sites. DHS 157.03(137)(137) “Film badge” means a dosimeter containing radiation sensitive photographic film for measuring radiation dose plus various filters that characterize the type of radiation encountered. When developed, the darkness of the film is directly proportional to the amount of radiation received. DHS 157.03(138)(138) “Filter” means material placed in the useful beam to preferentially absorb selected radiation energies. DHS 157.03(139)(139) “Filtering facepiece” means a negative pressure respirator with a filter as an integral part of the facepiece or with the entire facepiece composed of the filtering medium, not equipped with elastomeric sealing surfaces and adjustable straps. DHS 157.03 NoteNote: Elastomeric refers to material that is elastic and form fitting to provide a tight seal against the face.
DHS 157.03(139m)(139m) “Fingerprint order” means an order issued by the NRC, a license condition by the department, or a legally binding requirement issued by another agreement state that requires a fingerprints and criminal history records check for individuals who have unescorted access to category 1 and category 2 quantities of radioactive material or safeguards information-modified handling. DHS 157.03(140)(140) “Fissile material” means the radionuclides uranium-233, uranium-235, plutonium-239 and plutonium-241, or any combination of these radionuclides. Fissile material means the fissile nuclides themselves, not material containing fissile nuclides. Unirradiated natural uranium and depleted uranium, and natural uranium or depleted uranium that has been irradiated in thermal reactors only are not included in this definition. DHS 157.03 NoteNote: Certain exclusions from fissile material controls are provided in 10 CFR 71.15. DHS 157.03(141)(141) “Fissile material package” or Type AF package, Type BF package, Type B(U)F package, or Type B(M)F package means a fissile material packaging together with its fissile material contents. DHS 157.03(142)(142) “Fit factor” means a quantitative estimate of the fit of a particular respirator to a specific individual, and estimates the ratio of the concentration of a substance in ambient air to its concentration inside the respirator when worn. DHS 157.03(143)(143) “Fit test” means the use of a protocol to qualitatively or quantitatively evaluate the fit of a respirator on an individual. DHS 157.03(143g)(143g) “Fixed contamination” means contamination that cannot be removed from a surface during normal conditions of transport. DHS 157.03(143m)(143m) “Fluoroscopic air kerma display device” means a device, or subsystem, or component that provided the display of the air kerma rate and cumulative air kerma required by 21 CFR 1020.32 (k). It includes radiation detectors, if any, electronic and computer components, associated software, and display units. DHS 157.03(144)(144) “Fluoroscopic imaging assembly” means a subsystem in which x-ray photons produce a visible image. It includes the image receptor such as the image intensifier and spot-film device, electrical interlocks, if any, and structural material providing linkage between the image receptor and diagnostic source assembly. DHS 157.03(145)(145) “Fresh water aquifer” means, for the purposes of this chapter, a geologic formation that is capable of yielding fresh water to a well or spring. DHS 157.03(146)(146) “Gantry” means that part of a radiation therapy system supporting and allowing movements of the radiation head about a center of rotation. DHS 157.03(147)(147) “General purpose radiographic x-ray system” means any radiographic x-ray system, which, by design, is not limited to radiographic examination of specific anatomical regions. DHS 157.03(148)(148) “Gamma stereotactic radiosurgery” means the use of a device containing a radioactive material providing multiple point radiation therapy treatment to a specific tumor site. DHS 157.03(149)(149) “Generally applicable environmental radiation standards” means standards issued by the U.S. environmental protection agency under the authority of 42 USC 23, that impose limits on radiation exposures or levels, or concentrations or quantities of radioactive material, in the general environment outside the boundaries of locations under the control of persons possessing or using radioactive material. DHS 157.03(150)(150) “Gonad shield” means a protective barrier for the testes or ovaries. DHS 157.03(150g)(150g) “Government agency” means any executive department, commission, independent establishment, corporation, wholly or partly owned by the United States of America which is an instrumentality of the United States, or any board, bureau, division, service, office, officer, authority, administration, or other establishment in the executive branch of the Government. DHS 157.03(150m)(150m) “Graphite” means, for the purposes of 10 CFR 71.15 and 10 CFR 71.22, graphite with a boron equivalent content less than 5 parts per million and density greater than 1.5 grams per cubic centimeter. DHS 157.03(151)(151) “Gray” or “Gy” means the SI unit of absorbed dose, air kerma and specific energy imparted equal to one joule per kilogram. DHS 157.03 NoteNote: The special unit of absorbed dose is being replaced by the gray. 1 Gy equals 100 rad.
DHS 157.03(152)(152) “Guide tube” means a flexible or rigid tube, for guiding the source assembly and the attached control cable from the exposure device to the exposure head. The guide tube may also include the connections necessary for attachment to the exposure device and to the exposure head. DHS 157.03(153)(153) “Half-value layer” or “HVL” means the thickness of specified material which attenuates an x-ray or gamma radiation beam such that the air kerma rate at a point within the radiation beam is reduced to one-half of the air kerma rate at the same point without the material present. In this definition, the contribution of all scattered radiation, other than any that might be present initially in the radiation beam concerned, is excluded. DHS 157.03(154)(154) “Hands-on experience” means experience in all of those areas considered to be directly involved in the radiography process. DHS 157.03 NoteNote: “Hands-on experience” includes taking radiographs, calibration of survey instruments, operational and performance testing of survey instruments and devices, film development, posting of warning signs in radiation areas, transportation of radiography equipment, posting on a bulletin board of records and radiation area surveillance, as applicable.
DHS 157.03(155)(155) “Healing arts” means a profession concerned with diagnosis and treatment of human maladies, including the practice of medicine, dentistry, osteopathy chiropractic and podiatry. DHS 157.03(156)(156) “Healing arts screening” means the exposure of a human being to x-rays without prior examination disclosing a need for an x-ray procedure and prescription for such a study by a practitioner of the healing arts. DHS 157.03(157)(157) “Heat unit” means a unit of energy equal to 0.75 joule. It is approximately equal to the energy given by the product of the peak kilovoltage, milliampere and seconds, which is kVp x mA x time in seconds. DHS 157.03(158)(158) “Helmet” means a rigid respiratory inlet covering that also provides head protection against impact and penetration. DHS 157.03(159)(159) “High dose-rate remote afterloader” or “HDR” means a device that delivers a dose rate in excess of 12 gray (1200 rads) per hour. DHS 157.03(160)(160) “High radiation area” means an area, accessible to individuals, in which radiation levels from radiation sources external to the body could result in an individual receiving a dose equivalent in excess of one mSv (0.1 rem) in one hour at 30 centimeters from any source of radiation or 30 centimeters from any surface that the radiation penetrates. DHS 157.03(161)(161) “Hood” means a respiratory inlet covering that completely covers the head and neck and may also cover portions of the shoulders and torso. DHS 157.03(162)(162) “Human use” means the internal or external administration of radiation or radioactive material to human beings. DHS 157.03(163)(163) “Image intensifier” means a device, installed in its housing, which instantaneously converts an x-ray pattern into a corresponding light image of higher intensity. DHS 157.03(164)(164) “Image receptor support” means, for mammographic systems, that part of the system designed to support the image receptor during mammography. DHS 157.03(165)(165) “Image receptor” means any device, such as a fluorescent screen or radiographic film, which transforms incident x-ray photons either into a visible image or into another form that may be made into a visible image by further transformations. DHS 157.03(166)(166) “Independent certifying organization” means an independent organization that meets all of the criteria specified in 10 CFR 34, Appendix A. DHS 157.03(166m)(166m) “Indian Tribe” means an Indian or Alaska native tribe, band, nation, pueblo, village, or community that the Secretary of the Interior acknowledges to exist as an Indian tribe pursuant to the Federally Recognized Indian Tribe List Act of 1994, 25 U.S.C. 479a. DHS 157.03(168)(168) “Individual monitoring” means the assessment of any of the following:
