Chapter DHS 157

DHS 157.03 Note Note: Committed effective dose equivalent (HE,50) equals the sum of the weighting factor (wT,) times the committed dose equivalent (HT,50).

DHS 157.03(74) (74) “Computed tomography" or “CT" means the production of a tomogram by the acquisition and computer processing of x-ray transmission data.

DHS 157.03(75) (75) 

DHS 157.03(75)(a) (a) “Computed tomography dose index" or “CTDI" means the integral from -10T to +10T of the dose profile along a line perpendicular to the tomographic plane divided by the product of the nominal tomographic section thickness and the number of tomograms produced in a single scan, that is: - See PDF for table

where:

z = position along a line perpendicular to the tomographic plane;

D(z) = dose at position z;

T = nominal tomographic section thickness in millimeters;

n = number of tomograms produced in a single scan.

DHS 157.03(75)(b) (b) The definition of “computed tomography dose index" assumes that the dose profile is centered around z=0 and that, for a multiple tomogram system, the scan increment between adjacent scans is nT.

DHS 157.03(75m) (75m) “Consignment" means each shipment of a package or groups of packages or load of radioactive material offered by a shipper for transport.

DHS 157.03(75r) (75r) “Consortium" means an association of medical use licensees and a PET facility in the same geographical area, physically located at an educational institution, a federal facility or a medical facility, that jointly own or share in the operation and maintenance cost of the PET facility that produces PET radionuclides for use in producing radioactive drugs within the consortium for noncommercial distributions among its associated members for medical use.

DHS 157.03(76) (76) “Constraint" means a value above which specified licensee or registrant actions are required.

DHS 157.03(77) (77) “Contact therapy system" means a therapeutic radiation machine with a short target to skin distance, usually less than 5 centimeters.

DHS 157.03(77m) (77m) “Contamination” means the presence of a radioactive substance on a surface in quantities in excess of 0.4 Bq/cm2 (1x10-5 microcurie/cm2) for beta and gamma emitters and low toxicity alpha emitters, or 0.04 Bq/cm2 (1x10 -6 microcurie/cm2) for all other alpha emitters.

DHS 157.03(78) (78) “Control cable" means the cable that is connected to the source assembly and used to drive the source to and from the exposure location.

DHS 157.03(79) (79) “Control drive mechanism" means a device that enables the source assembly to be moved into and out of the exposure device.

DHS 157.03(80) (80) “Control panel" means that part of an x-ray control upon which are mounted the switches, knobs, pushbuttons and other hardware necessary for manually setting the technique factors.

DHS 157.03(81) (81) “Control tube" means a protective sheath for guiding the control cable. The control tube connects the control drive mechanism to the radiographic exposure device.

DHS 157.03(82) (82) “Controlled area" means an area, outside of a restricted area but inside the site boundary, access to which may be limited by the licensee or registrant for any reason.

DHS 157.03(82m) (82m) “Conveyance" means any one of the following:

DHS 157.03(82m)(a) (a) For transport by public highway or rail, any transport vehicle or large freight container.

DHS 157.03(82m)(b) (b) For transport by water, any vessel, or any hold, compartment or defined deck area of a vessel, including any transport vehicle on board the vessel.

DHS 157.03(82m)(c) (c) For transport by aircraft, any aircraft.

DHS 157.03(83) (83) “Cooling curve" means the graphical relationship between heat units stored and cooling time.

DHS 157.03(84) (84) “Critical group" means the group of individuals reasonably expected to receive the greatest exposure to residual radioactivity for any applicable set of circumstances.

DHS 157.03(84m) (84m) "Criticality safety index" or "CSI" means the dimensionless number, rounded up to the next tenth, assigned to and placed on the label of a fissile material package to designate the degree of control of accumulation of packages, overpacks, or freight containers containing fissile material during transportation.

DHS 157.03 Note Note: Determination of the criticality safety index is described in s. DHS 157.93 (7) and (8) and 10 CFR 71.59. The CSI for an overpack, freight container, consignment or conveyance containing fissile material packages is the arithmetic sum of the criticality safety indices of all the fissile material packages contained within the overpack freight container, consignment, or conveyance.

DHS 157.03(85) (85) “CT conditions of operation" means all selectable parameters governing the operation of a CT x-ray system including nominal tomographic section thickness, filtration and the technique factors as defined in s. DHS 157.84.

DHS 157.03(86) (86) “CT gantry" means the tube housing assemblies, beam-limiting devices, detectors and the supporting structures and frames that hold these components.

DHS 157.03(87) (87) “CT number" or “CTN" means the number used to represent the x-ray attenuation associated with each elemental area of the CT image as expressed in the following equation:

- See PDF for diagram

where:

K = a constant, a normal value of 1,000 when the Houndsfield scale of CTN is used;

- See PDF for diagram = linear attenuation coefficient of the material of interest;

- See PDF for diagram = linear attenuation coefficient of water.

DHS 157.03(87m) (87m) “Cumulative air kerma" means the total air kerma accrued from the beginning of an examination or procedure and includes all contributions from fluoroscopic and radiographic irradiation.

DHS 157.03(88) (88) “Curie" or “Ci" means 3.7 x 1010 disintegrations per second = 3.7 x 1010 becquerels = 2.22 x 1012 disintegrations per minute.

DHS 157.03(89) (89) “Dead-man switch" means a switch so constructed that a circuit closing contact may be maintained only by continuous pressure on the switch by the operator.

DHS 157.03(90) (90) “Declared pregnant woman" means a woman who has voluntarily informed the licensee or registrant, in writing, of her pregnancy and the estimated date of conception. The declaration remains in effect until the declared pregnant woman withdraws the declaration in writing or is no longer pregnant.

DHS 157.03(91) (91) “Decommission" means to remove a facility or site safely from service and reduce residual radioactivity to a level that permits release of the property for unrestricted use and termination of the license; or release of the property under restricted conditions and termination of the license.

DHS 157.03(92) (92) “Dedicated check source" means a radioactive source that is used to assure the constant operation of a radiation detection or measurement device over several months or years.

DHS 157.03(93) (93) “Deep dose equivalent" or “Hd" means the dose equivalent at a tissue depth of one centimeter (1000 mg/cm2) and applies to external whole body exposure.

DHS 157.03(94) (94) “Deliberate misconduct" means an intentional act or omission that the person knows would cause any of the following:

DHS 157.03(94)(a) (a) A licensee, registrant or applicant to be in violation of any requirement under this chapter, any order of the department, or any term, condition or limitation of any license or registration issued by the department under this chapter.

DHS 157.03(94)(b) (b) A violation of a requirement, procedure, instruction, contract, purchase order or policy of a licensee, registrant, applicant, or contractor or subcontractor of a licensee, registrant or applicant.

DHS 157.03(95) (95) “Demand respirator" means an atmosphere-supplying respirator that admits breathing air to the face piece only when a negative pressure is created inside the facepiece by inhalation.

DHS 157.03(96) (96) “Dentist" means an individual licensed under ch. 447, Stats., to practice dentistry.

DHS 157.03(97) (97) “Department" means the department of health services.

DHS 157.03(98) (98) “Depleted uranium" means uranium containing less uranium-235 than the naturally occurring distribution of uranium isotopes.

DHS 157.03(99) (99) “Derived air concentration" or “DAC" means the concentration of a given radionuclide in air which, if breathed by the reference man for a working year of 2,000 hours under conditions of light work, results in an intake of one ALI.

DHS 157.03 Note Note: For purposes of this chapter, the condition of light work is an inhalation rate of 1.2 cubic meters of air per hour for 2,000 hours in a year. DAC values are given in Table I, column 3, of ch. DHS 157 Appendix E.

DHS 157.03(100) (100) “Derived air concentration-hour" or “DAC-hour" means the product of the concentration of radioactive material in air, expressed as a fraction or multiple of the derived air concentration for each radionuclide, and the time of exposure to that radionuclide, in hours. A licensee or registrant may take 2,000 DAC-hours to represent one ALI, equivalent to a committed effective dose equivalent of 0.05 Sv (5 rem).

DHS 157.03(101) (101) “Detector" means a device which in the presence of radiation provides, by either direct or indirect means, a signal or other indication suitable for use in measuring one or more quantities of incident radiation.

DHS 157.03(101m) (101m) “Deuterium" means deuterium and any deuterium compounds, including heavy water, in which the ratio of deuterium atoms to hydrogen atoms exceeds 1:5000.

DHS 157.03(102) (102) “Diagnostic source assembly" means the tube housing assembly with a beam-limiting device attached.

DHS 157.03(103) (103) “Diagnostic x-ray imaging system" means an assemblage of components for the generation, emission and reception of x-rays and the transformation, storage and visual display of the resultant x-ray image.

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 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 “H T" 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:

- See PDF for diagram

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 = ∑ 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.

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.