DHS 157.03(369)(369) “Surface casing for protecting fresh water aquifers” means a pipe or tube used as a lining in a well to isolate fresh water aquifers from the well. DHS 157.03(370)(370) “Surface contaminated object” or “SCO” means a solid object that is not itself classed as radioactive material, but which has radioactive material distributed on any of its surfaces. DHS 157.03(371)(371) “Survey” means an evaluation of the radiological conditions and potential hazards incident to the production, use, transfer, release, disposal or presence of sources of radiation. When appropriate, an evaluation includes tests, physical examinations and measurements of levels of radiation or concentrations of radioactive material present. DHS 157.03(371m)(371m) “Tailing” means the residual material resulting from the extraction of minerals from the earth. DHS 157.03(372)(372) “Target” means that part of an x-ray tube or accelerator onto which a beam of accelerated particles is directed to produce ionizing radiation or other particles. DHS 157.03(373)(373) “Target-skin distance” or “TSD” means the distance measured along the beam axis from the center of the front surface of the x-ray target or electron virtual source to the surface of the irradiated object or patient. DHS 157.03(374)(374) “Technique factors” means the following conditions of operation: DHS 157.03(374)(a)(a) For capacitor energy storage equipment, peak tube potential in kV and quantity of charge in mAs. DHS 157.03(374)(b)(b) For field emission equipment rated for pulsed operation, peak tube potential in kV and number of x-ray pulses. DHS 157.03(374)(c)(c) For CT equipment designed for pulsed operation, peak tube potential in kV, scan time in seconds, and either tube current in milliamperes (mA), x-ray pulse width in milliseconds, and the number of x-ray pulses per scan; or the product of tube current, x-ray pulse width, and the number of x-ray pulses per scan expressed as mAs. DHS 157.03(374)(d)(d) For CT x-ray equipment not designed for pulsed operation, peak tube potential in kV, and either tube current in mA and scan time in seconds, or the product of tube current and exposure time in mAs and the scan time when the scan time and exposure time are equivalent. DHS 157.03(374)(e)(e) For all other equipment, peak tube potential in kV and either tube current in mA and exposure time in seconds or the product of tube current and exposure time in mAs. DHS 157.03(374m)(374m) “Telemetric position monitoring system” means a data transfer system that captures information by instrumentation or measuring devices about the location and status of a transport vehicle or package between the departure and destination locations. DHS 157.03(375)(375) “Teletherapy” means a method of radiation therapy in which collimated gamma rays are delivered from a source at a distance from the patient or human research subject. DHS 157.03(376)(376) “Temporary job site” means a location where any of the following occur: DHS 157.03(376)(a)(a) Radiographic operations are performed and sources of radiation may be stored other than at the location or locations of use authorized on the license or registration. DHS 157.03(376)(b)(b) Radioactive materials are present for the purpose of performing well logging or subsurface tracer studies. DHS 157.03(377)(377) “Tenth-value layer” or “TVL” means the thickness of a specified material that attenuates x-radiation or gamma radiation to an extent that the air kerma rate; exposure rate or absorbed dose rate is reduced to one-tenth of the value measured without the material at the same point. DHS 157.03(378)(378) “Termination of irradiation” means the stopping of irradiation in a fashion that will not permit continuance of irradiation without the resetting of operating conditions at the control panel. DHS 157.03(379)(379) “Test” means the process of verifying compliance with an applicable regulation. DHS 157.03(380)(380) “Therapeutic dosage” means a dosage of an unsealed radioactive material that is intended to deliver a radiation dose to a patient or human research subject for palliative or curative treatment. DHS 157.03(381)(381) “Therapeutic dose” means a radiation dose delivered from a sealed source containing radioactive material to a patient or human research subject for palliative or curative treatment. DHS 157.03(382)(382) “Therapeutic radiation machine” means x-ray, gamma ray or electron-producing equipment designed and used for external beam or internal radiation therapy. DHS 157.03(383)(383) “Thermoluminescent dosimeter” or “TLD” means a dosimeter containing a crystalline solid for measuring radiation dose, plus filters to help characterize the types of radiation encountered. When heated, TLD crystals that have been exposed to ionizing radiation give off light proportional to the energy they received from the radiation. DHS 157.03(384)(384) “Tight-fitting facepiece” means a respiratory inlet covering that forms a complete seal with the face. DHS 157.03(385)(385) “Tomogram” means the depiction of the x-ray attenuation properties of a section through the body. DHS 157.03(386)(386) “Tomographic plane” means that geometric plane which is identified as corresponding to the output tomogram. DHS 157.03(387)(387) “Tomographic section” means the volume of an object whose x-ray attenuation properties are imaged in a tomogram. DHS 157.03(388)(388) “Total effective dose equivalent” or “TEDE” means the sum of the effective dose equivalent for external exposures and the committed effective dose equivalent for internal exposures.