Chapter DHS 157

DHS 157.77(3) (3) Source-to-skin distance. All mobile or portable radiographic systems shall be provided with means to limit the source-to-skin distance to equal to or greater than 30 centimeters, except for veterinary systems.

DHS 157.77(4) (4) Air kerma reproducibility. When all technique factors are held constant, including control panel selections associated with automatic exposure control systems, the coefficient of variation of air kerma for both manual and automatic exposure control systems may not exceed 0.05. This requirement applies to clinically used techniques.

DHS 157.77(5) (5) Radiation from capacitor energy storage equipment in standby status. Radiation emitted from the x-ray tube when the system is fully charged and the exposure switch or timer is not activated may not exceed any of the following:

DHS 157.77(5)(a) (a) A rate of 0.26mGy (0.03mR exposure) in one minute at 5 centimeters from any accessible surface of the diagnostic source assembly with the beam-limiting device fully open.

DHS 157.77(5)(b) (b) An air kerma of 0.88 mGy (100mr/exposure) in one hour at 100 centimeters from the x-ray source, with the beam-limiting device fully open, when the system is discharged through the x-ray tube either manually or automatically by use of a discharge switch or deactivation of the input power. Compliance shall be determined by measurements of the maximum air kerma per discharge multiplied by the total number of discharges in one hour (duty cycle). The measurements shall be averaged over an area of 100 square centimeters with no linear dimension greater than 20 centimeters.

DHS 157.77(6) (6) Accuracy. Deviation of measured technique factors from indicated values of kVp and exposure time may not exceed the limits specified for that system by its manufacturer. In the absence of manufacturer’s specifications, the deviation may not exceed 10% of the indicated value for kVp and 10% of the time limit.

DHS 157.77(7) (7) mA/mAs linearity. X-ray equipment that is operated on a power supply as specified by the manufacturer for any fixed x-ray tube potential within the range of 40% to 100% of the maximum rated shall meet all the following requirements:

DHS 157.77(7)(a) (a) Equipment having independent selection of x-ray tube current (mA). The average ratios of exposure to the indicated milliampere-seconds product obtained at any 2 consecutive tube current settings may not differ by more than 0.10 times their sum:

X1-X2 < 0.10 (X1+X2)

where X1 and X2 are the average values obtained at any of 2 consecutive tube current settings or at 2 settings differing by no more than a factor of 2 where the tube current selection is continuous.

DHS 157.77(7)(b) (b) Equipment having a combined x-ray tube current-exposure time product selector, but not a separate tube current selector. The average ratios of exposure to the indicated milliampere-seconds product, in units of .001 mGy/mAs (mR/mAs), obtained at any 2 consecutive mAs selector settings may not differ by more than 0.10 times their sum:

X1-X2 < 0.10 (X1 +X2)

where X1 and X2 are the average values obtained at any 2 consecutive mAs selector settings, or at 2 settings differing by no more than a factor of 2 where the mAs selector provides continuous selection.

DHS 157.77(7)(c) (c) Measuring compliance. Determination of compliance shall be based on 10 exposures taken within a time period of one hour at each of the 2 settings. These 2 settings may include any 2 focal spot sizes except where one is equal to or less than 0.45 millimeters and the other is greater than 0.45 millimeters. For purposes of this requirement, focal spot size is the nominal focal spot size specified by an x-ray tube manufacturer.

DHS 157.77(8) (8) Additional requirements applicable to certified systems only. A diagnostic x-ray system incorporating one or more certified components shall meet all of the following additional requirements that relate to that certified component or components:

DHS 157.77(8)(a) (a) Beam limitation for stationary and mobile general purpose x-ray systems. Stationary and mobile general purpose x-ray systems shall meet all the following beam limitation requirements:

DHS 157.77(8)(a)1. 1. There shall be provided a means of stepless adjustment of the size of the x-ray field. The minimum field size at a SID of 100 centimeters shall be equal to or less than 5 centimeters by 5 centimeters.

DHS 157.77(8)(a)2. 2. When a light localizer type of collimator is used to define the x-ray field, it shall provide an average illumination of not less than 160 lux or 15 footcandles at 100 centimeters or at the maximum SID, whichever is less. The average illumination shall be based upon measurements made in the approximate center of each quadrant of the light field. Radiation therapy simulation systems manufactured on and after May 27, 1980, are exempt from this requirement.

DHS 157.77(8)(a)3. 3. The edge of the light field at 100 centimeters or at the maximum SID, whichever is less, shall have a contrast ratio, corrected for ambient lighting, of not less than 4 in the case of beam-limiting devices designed for use on stationary equipment, and a contrast ratio of not less than 3 in the case of beam-limiting devices designed for use on mobile equipment. The contrast ratio is defined as I1/I2 where I1 is the illumination 3 millimeters from the edge of the light field toward the center of the field; and I2 is the illumination 3 millimeters from the edge of the light field away from the center of the field. Compliance shall be determined with a measuring instrument aperture of one millimeter in diameter.

DHS 157.77(8)(b) (b) Beam limitation and alignment on stationary general purpose x-ray systems equipped with PBL. If PBL is being used, the x-ray system shall meet all of the following requirements:

DHS 157.77(8)(b)1. 1. PBL shall prevent the production of x-rays when either one of the following occurs:

DHS 157.77(8)(b)1.a. a. The length or width of the x-ray field in the plane of the image receptor differs, except as permitted by manual override, from the corresponding image receptor dimensions by more than 3% of the SID.

DHS 157.77(8)(b)1.b. b. The sum of the length and width differences, without regard to positive or negative mathematical sign, exceeds 4% of the SID.

DHS 157.77(8)(b)2. 2. Compliance for exposure lock-out shall be determined when the equipment indicates that the beam axis is perpendicular to the plane of the image receptor. Compliance shall be determined no more than 5 seconds after insertion of the image receptor.

DHS 157.77(8)(b)3. 3. The PBL system shall be capable of operation, at the discretion of the operator, such that the size of the field may be made smaller than the size of the image receptor through adjustment of the field size. The minimum field size at a SID of 100 centimeters shall be equal to or less than 5 centimeters by 5 centimeters.

DHS 157.77(8)(b)4. 4. The PBL system shall be designed such that a change in image receptor causes the automatic return to PBL.

DHS 157.77(8)(c) (c) Beam limitation for portable x-ray systems. Beam limitation for portable x-ray systems shall meet the beam limitation requirements for manual collimators.

DHS 157.77(9) (9) Tube stands for portable x-ray systems. A tube stand or other mechanical support shall be used for portable x-ray systems so that the x-ray tube housing assembly need not be hand-held during exposures.

DHS 157.77 History History: CR 01-108: cr. Register July 2002 No. 559, eff. 8-1-02; CR 06-021: r. and recr. (5) Register October 2006 No. 610, eff. 11-1-06; CR 09-062: am. (2) (g) Register April 2010 No. 652, eff. 5-1-10; CR 16-078: am. (2) (h) 1., (i) Register January 2018 No. 745, eff. 2-1-18.

DHS 157.78 DHS 157.78 Intraoral dental radiographic systems.

DHS 157.78(1) (1) General. In addition to the provisions of ss. DHS 157.74 and 157.75, the requirements in this section apply to x-ray equipment and associated facilities used for dental radiography. Requirements for extraoral dental radiographic systems are contained in s. DHS 157.77.

DHS 157.78(2) (2) Source-to-skin distance. X-ray systems designed for use with an intraoral image receptor shall be provided with means to limit source-to-skin distance to not less than either one of the following:

DHS 157.78(2)(a) (a) 20 centimeters (8 inches) if operable above 50 kVp. Beam-limiting devices shall be lead lined.

DHS 157.78(2)(b) (b) 10 centimeters (4 inches) if operable at 50 kVp only. Beam-limiting devices shall be lead lined.

DHS 157.78(3) (3) Beam limitation. Radiographic systems designed for use with an intraoral image receptor shall be provided with means to limit the x-ray beam such that the beam at the minimum SSD shall be contained in a circle having a diameter of no more than 7 centimeters.

DHS 157.78(4) (4) Radiation exposure control. Intraoral radiographic systems shall meet all of the following exposure control requirements:

DHS 157.78(4)(a) (a) Exposure initiation. Means shall be provided to initiate the radiation exposure by a deliberate action on the part of the operator, such as the depression of a switch. Radiation exposure may not be initiated without such an action. An exposure may not be made when the timer is set to a “zero” or “off” position if either position is provided.

DHS 157.78(4)(b) (b) Exposure indication. Means shall be provided for visual exposure indication observable at or from the operator’s protected position whenever x-rays are produced. In addition, a signal audible to the operator shall indicate that the exposure has terminated.

DHS 157.78(4)(c) (c) Exposure termination. Means shall be provided to terminate the exposure at a preset time interval, preset product of current and time, a preset number of pulses or a preset radiation exposure to the image receptor. Termination of an exposure shall cause automatic resetting of the timer to its initial setting or to “zero” except for panoramic systems that may pause during the exposure cycle.

DHS 157.78(4)(d) (d) Exposure control location and operator protection. An x-ray system shall meet all the following requirements, as applicable, to ensure operator protection during use of the system:

DHS 157.78(4)(d)1. 1. A stationary x-ray system shall have an x-ray exposure control that is operable from behind a protective barrier during the entire exposure. The exposure control cord shall be of sufficient length to allow the operator to be at least 2 meters (6.5 feet) from the x-ray tube head and not in the direction of the primary beam. The operator shall be able to determine when the exposure has completed either by audible tone or visible signal.

DHS 157.78(4)(d)2. 2. A mobile or portable x-ray system that is used for greater than one week in the same location, which is a room or suite, shall meet the requirements of stationary dental equipment.

DHS 157.78(4)(d)3. 3. A mobile or portable x-ray system that is used for less than one week in the same location shall be provided with either a protective barrier at least 2 meters (6.5 feet) high for operator protection or means to allow the operator to be at least 2 meters (6.5 feet) from the tube housing assembly during exposures.

DHS 157.78(5) (5) Reproducibility. When the equipment is operated on an adequate power supply as specified by the manufacturer, the estimated coefficient of variation of air kerma may be no greater than 0.05 for any specific combination of selected technique factors.

DHS 157.78(6) (6) mA/mAs linearity. X-ray equipment that is operated on a power supply as specified by the manufacturer for any fixed x-ray tube potential within the range of 40% to 100% of the maximum rated shall meet all of the following requirements:

DHS 157.78(6)(a) (a) Equipment having independent selection of x-ray tube current. The average ratios of air kerma to the indicated milliampere-seconds product, in units of .001 mGy/mAs (mR/mAs), obtained at any 2 consecutive tube current settings may not differ by more than 0.10 times their sum:

X1 - X2 < 0.10 (X1+X2)

where X1 and X2 are the average values obtained at each of 2 consecutive tube current settings, or at 2 settings differing by no more than a factor of 2 where the tube current selection is continuous.

DHS 157.78(6)(b) (b) Equipment having a combined x-ray tube current-exposure time product selector but not a separate tube current selector. The average ratios of air kerma to the indicated milliampere-seconds product, in units of .001 mGy/mAs (mR/mAs), obtained at any 2 consecutive mAs selector settings may not differ by more than 0.10 times their sum:

X1 - X2 < 0.10 (X1 +X2)

where X1 and X2 are the average values obtained at any 2 consecutive mAs selector settings, or at 2 settings differing by no more than a factor of 2 where the mAs selector provides continuous selection.

DHS 157.78(6)(c) (c) Measuring compliance. Determination of compliance shall be based on 10 exposures taken within a time period of one hour at each of the 2 settings. The 2 settings may include any 2 focal spot sizes except where one is equal to or less than 0.45 millimeters and the other is greater than 0.45 millimeters. For purposes of this requirement, focal spot size is the nominal focal spot size specified by an x-ray tube manufacturer.

DHS 157.78(7) (7) Accuracy. Deviation of technique factors from indicated values for kVp and exposure time, if time is independently selectable, may not exceed the limits specified for that system by its manufacturer. In the absence of manufacturer’s specifications the deviation may not exceed 10% of the indicated value for kVp and 10% for time.

DHS 157.78(8) (8) kVp limitations. Dental x-ray machines with a nominal fixed kVp of less than 50 kVp may not be used to make diagnostic dental radiographs of humans.

DHS 157.78(9) (9) Administrative controls.

DHS 157.78(9)(a) (a) Intraoral image receptor devices shall be used.

DHS 157.78(9)(b) (b) The tube housing and the cone may not be hand-held during an exposure.

DHS 157.78(9)(c) (c) The tube shall be stationary during exposure, except for panoramic systems. Any oscillation of the tube head shall cease before exposure is made.

DHS 157.78(10) (10) Hand-held intraoral dental radiographic units. A dental radiographic unit that is designed to be operated as a hand-held unit shall meet all the following requirements:

DHS 157.78(10)(a) (a) For all uses:

DHS 157.78(10)(a)1. 1. Operators of hand-held intraoral dental radiographic units shall be trained to operate such equipment. The training shall cover: manufacturer specific exposure control, use of safety devices, operator and patient protection, and quality control testing.

DHS 157.78(10)(a)2. 2. When operating a hand-held intraoral dental radiographic unit, operators shall wear a lead apron and thyroid collar unless the hand-held intraoral device has a secondary protective barrier.

DHS 157.78(10)(a)3. 3. A hand-held intraoral dental radiographic unit shall be immobilized during a patient examination. A tube stand may be utilized to immobilize a hand-held intraoral dental radiographic unit during patient examination.

DHS 157.78(10)(a)4. 4. The operator shall ensure there are no bystanders within a radius of at least 2 meters (6.5 ft) from the patient being examined during exposures.

DHS 157.78(10)(b) (b) For permanent facilities:

DHS 157.78(10)(b)1. 1. Hand-held intraoral dental radiographic units shall be used for patient examinations in dental offices that meet the structural shielding requirements specified by the department.

DHS 157.78(10)(b)2. 2. Hand-held intraoral dental radiographic units may not be used for patient examinations in hallways and waiting rooms.

DHS 157.78 History History: CR 01-108: cr. Register July 2002 No. 559, eff. 8-1-02; CR 16-078: am. (4) (d) 1., 3., (8) (title), (9) (a), cr. (10) Register January 2018 No. 745, eff. 2-1-18.

DHS 157.79 DHS 157.79 Veterinary medicine x-ray systems.

DHS 157.79(1) (1) General. The requirements of this section apply to all animal use x-ray systems used in veterinary practice and are in addition to other provisions in subchs. I and III.

DHS 157.79(2) (2) Equipment.

DHS 157.79(2)(a) (a) The tube housing shall be electrically shock proof and of a diagnostic type. The x-ray tube may not be hand-held during exposures.

DHS 157.79(2)(b) (b) A device shall be provided to terminate the exposure after a preset time or exposure.

DHS 157.79(2)(c) (c) A dead-man type of exposure switch shall be provided with an electrical cord of sufficient length so that the operator or the assistant, may stand out of the useful beam and at least 2 meters (6.5 feet) from the table during all x-ray exposures. A foot operated exposure switch may be used and this switch may be integrated into the table base or the foot switch may be on a 2 meter (6.5 feet) cord.

DHS 157.79(3) (3) Operating procedures.

DHS 157.79(3)(a) (a) The operator shall stand at least 2 meters (6.5 feet) from the tube housing and the animal during radiographic exposures. The operator may not stand in the useful beam. Hand-held fluoroscopic screens may not be used. The tube housing may not be held by the operator. No person other than the operator may be in an x-ray room while exposures are being made unless another person’s assistance is required.

DHS 157.79(3)(b) (b) During any application in which the operator is not located behind a protective barrier, the operator and any other persons in the room during exposures shall wear protective clothing consisting of a protective apron having a lead equivalent of not less than 0.5 millimeter unless measurements indicate otherwise.

DHS 157.79(3)(c) (c) Any person holding or supporting an animal or the image receptor during radiation exposure shall wear protective gloves that surround the hand and a protective apron having a lead equivalent of not less than 0.25 millimeter. Devices that only partially shield the hands are prohibited.

DHS 157.79(3)(d) (d) Veterinary fluoroscopy systems shall be operated only under the direct supervision of the licensed veterinarian.

DHS 157.79(4) (4) Animal support. Mechanical restraints shall be used to restrict movement of the animal unless the restraints interfere with the examination of the animal. No persons may be regularly utilized to hold or support animals during radiation exposures. Operating personnel may not perform this service except in cases where no other person is available.

DHS 157.79 History History: CR 01-108: cr. Register July 2002 No. 559, eff. 8-1-02; CR 06-021: am. (2) (c) Register October 2006 No. 610, eff. 11-1-06; CR 09-062: am. (2) (c) Register April 2010 No. 652, eff. 5-1-10; CR 16-078: am. (3) (c) Register January 2018 No. 745, eff. 2-1-18.

DHS 157.80 DHS 157.80 Computed tomography x-ray systems.

DHS 157.80(1) (1) Equipment requirements. A computed tomography (CT) x-ray system shall meet all of the following requirements, as applicable:

DHS 157.80(1)(a) (a) Termination of exposure.

DHS 157.80(1)(a)1. 1. Means shall be provided to terminate the x-ray exposure automatically by either de-energizing the x-ray source or shuttering the x-ray beam in the event of equipment failure affecting data collection. The termination shall occur within an interval that limits the total scan time to no more than 110% of its preset value through the use of either a back-up timer or devices which monitor equipment function. A visible signal shall indicate when the x-ray exposure has been terminated. The operator shall be able to terminate the x-ray exposure at any time during a scan, or series of scans under CT x-ray system control, of greater than one-half second duration.

DHS 157.80(1)(a)2. 2. For systems that allow high voltage to be applied to the x-ray tube continuously and that control the emission of x-ray with a shutter, the radiation emitted may not exceed 0.88 mGy (100mR) in 1 hour at any point 5 centimeters outside the external surface of the housing of the scanning mechanism when the shutter is closed.

DHS 157.80(1)(a)3. 3. Compliance shall be determined by measurements averaged over an area of 100 square centimeters with no linear dimension greater than 20 centimeters.

DHS 157.80(1)(b) (b) Tomographic plane indication and alignment.

DHS 157.80(1)(b)1. 1. A single tomogram system shall allow for visual determination of the tomographic plane or a reference plane offset from the tomographic plane.