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 Note Note: 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 Note Note: 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.