Chapter DHS 157

DHS 157.76(7) (7) Fluoroscopic irradiation time, display, and signal.

DHS 157.76(7)(a) (a) Fluoroscopic equipment manufactured before June 10, 2006, shall be provided with means to preset the cumulative irradiation time of the fluoroscopic tube. The maximum cumulative time of the timing device shall not exceed 5 minutes without resetting. A signal audible to the fluoroscopist shall indicate the completion of any preset cumulative Irradiation time. Such signal shall continue to sound while x-rays are produced until the timing device is reset.

DHS 157.76(7)(b) (b) As an alternative to the requirements of par. (a), radiation therapy simulation systems may be provided with a means to indicate the total cumulative exposure time during which x-rays were produced, and which is capable of being reset between x-ray examinations.

DHS 157.76(7)(c) (c) For x-ray controls manufactured on or after June 10, 2006, all of the following shall be provided for each fluoroscopic tube:

DHS 157.76(7)(c)1. 1. A display of the fluoroscopic irradiation time at the fluoroscopist’s working position.

DHS 157.76(7)(c)2. 2. The display required in subd. 1. shall function independently of the audible signal described in par. (a) and meet all the following requirements:

DHS 157.76(7)(c)2.a. a. When the x-ray tube is activated, the fluoroscopic irradiation time in minutes and tenths of minutes shall be continuously displayed and updated at least once every 6 seconds.

DHS 157.76(7)(c)2.b. b. The fluoroscopic irradiation time shall also be displayed within 6 seconds of termination of an exposure and remain displayed until reset.

DHS 157.76(7)(c)2.c. c. Means shall be provided to reset the display to zero prior to the beginning of a new examination or procedure.

DHS 157.76(7)(c)3. 3. A signal audible to the fluoroscopist shall sound for each passage of 5 minutes of fluoroscopic irradiation time during an examination or procedure. The signal shall sound until manually reset or, if automatically reset, for at least 2 seconds.

DHS 157.76(7)(d) (d) If fluoroscopic equipment is modified in accordance with 21 CFR 1020.30(q) to comply with the requirements in par. (a), it shall bear a label that states:

Modified to comply with 21 CFR 1020.32(h)(2)

DHS 157.76(8) (8) Mobile and portable fluoroscopes. Mobile and portable fluoroscopes shall use image-intensification or a direct-digital receptor.

DHS 157.76(9) (9) Display of last-image-hold.

DHS 157.76(9)(a) (a) Fluoroscopic equipment manufactured on or after June 10, 2006, shall be equipped with means to display the last image following termination of the fluoroscopic exposure.

DHS 157.76(9)(b) (b) For an LIH obtained by retaining pre-termination fluoroscopic images, if the number of images and method of combining images are selectable by the user, the selection shall be indicated prior to initiation of the fluoroscopic exposure.

DHS 157.76(9)(c) (c) For an LIH image obtained by initiating a separate radiographic-like exposure at the termination of fluoroscopic imaging, the technique factors for the LIH image shall be selectable prior to the fluoroscopic exposure, and the combination selected shall be indicated prior to initiation of the fluoroscopic exposure.

DHS 157.76(9)(d) (d) Means shall be provided to clearly indicate to the user whether a displayed image is the LIH radiograph or fluoroscopy. Display of the LIH radiograph shall be replaced by the fluoroscopic image concurrently with re-initiation of fluoroscopic exposure, unless separate displays are provided for the LIH radiograph and fluoroscopic images.

DHS 157.76(9)(e) (e) The predetermined or selectable options for producing the LIH radiograph shall be described in the information required by 21 CFR 1020.30 (h). The information shall include a description of any technique factors applicable for the selected option and the impact of the selectable options on image characteristics and the magnitude of radiation emissions.

DHS 157.76(10) (10) Displays of values of air kerma rate and cumulative air kerma. Fluoroscopic equipment manufactured on or after June 10, 2006, shall display at the fluoroscopist’s working position the air kerma rate and cumulative air kerma. Each x-ray tube used during an examination or procedure shall meet all the following requirements:

DHS 157.76(10)(a) (a) When the x-ray tube is activated and the number of images produced per unit time is greater than 6 images per second, the air kerma rate in mGy/min shall be continuously displayed and updated at least once every second.

DHS 157.76(10)(b) (b) The cumulative air kerma in units of mGy shall be displayed either within 5 seconds of termination of an exposure or displayed continuously and updated at least once every 5 seconds.

DHS 157.76(10)(c) (c) The display of the air kerma rate shall be clearly distinguishable from the display of the cumulative air kerma.

DHS 157.76(10)(d) (d)

DHS 157.76(10)(d)1. 1. The air kerma rate and cumulative air kerma shall represent the value for conditions of free-in-air irradiation at one of the referenced locations.

DHS 157.76(10)(d)2. 2. For fluoroscopes with x-ray source below the x-ray table, x-ray source above the table, or of lateral type, the reference locations shall be the respective locations specified in sub. (4) for measuring compliance with air kerma rate limits.

DHS 157.76(10)(d)3. 3. For C-arm fluoroscopes, the reference location shall be 15 cm from the isocenter toward the x-ray source along the beam axis. Alternatively, the reference location shall be at a point specified by the manufacturer to represent the location of the intersection of the x-ray beam with the patient’s skin.

DHS 157.76 Note Note: The reference location is identified and described specifically in the information provided to users according to 21 CFR 1020.30 (h) (6) (iii).

DHS 157.76(10)(e) (e) Means shall be provided to reset to zero the display of cumulative air kerma prior to the commencement of a new examination or procedure.

DHS 157.76(10)(f) (f) The displayed air kerma rate and cumulative air kerma shall not deviate from the actual values by more than ±35 percent over the range of 6 mGy/min and 100 mGy to the maximum indication of air kerma rate and cumulative air kerma, respectively. Compliance shall be determined with an irradiation time greater than 3 seconds.

DHS 157.76(11) (11) Equipment operations.

DHS 157.76(11)(a) (a) The registrant shall ensure that only a licensed practitioner or a radiologic technologist who is trained in the safe use of fluoroscopic x-ray systems is allowed to operate these systems. All fluoroscopic x-ray images shall be viewed, directly or indirectly, and interpreted by a licensed practitioner.

DHS 157.76(11)(b) (b) The use of fluoroscopic x-ray systems by radiologic technologists shall be performed under the supervision of a licensed practitioner for the purpose of localization to obtain images for diagnostic purposes.

DHS 157.76(11)(c) (c) Radiologic technology students may not operate fluoroscopic x-ray systems except under the direct supervision of a licensed practitioner or radiologic technologist.

DHS 157.76(11)(d) (d) Fluoroscopic x-ray systems may not be used as a positioning tool for general purpose radiographic examinations.

DHS 157.76(11)(e) (e) The registrant shall require the operator of a fluoroscopic x-ray system to meet either of the following requirements:

DHS 157.76(11)(e)1. 1. Is certified by the American Board of Radiology or board eligible.

DHS 157.76(11)(e)2. 2. Has completed training to include the following:

DHS 157.76(11)(e)2.a. a. Principles and operation of the fluoroscopic x-ray system.

DHS 157.76(11)(e)2.b. b. Biological effects of x-ray.

DHS 157.76(11)(e)2.c. c. Principles of radiation protection.

DHS 157.76(11)(e)2.d. d. Fluoroscopic outputs.

DHS 157.76(11)(e)2.e. e. High level control options.

DHS 157.76(11)(e)2.f. f. Dose reduction techniques for fluoroscopic x-ray systems.

DHS 157.76(11)(e)2.g. g. Applicable state and federal regulations.

DHS 157.76(12) (12) Air kerma measurements. Annual measurements of both typical and maximum air kerma shall be made by a medical physicist or a person approved by a medical physicist.

DHS 157.76 Note Note: Materials should be placed in the useful beam to protect the imaging system when conducting these periodic measurements. Air kerma measurements do not include backscatter.

DHS 157.76 History History: CR 01-108: cr. Register July 2002 No. 559, eff. 8-1-02; CR 06-021: r. and recr. Register October 2006 No. 610, eff. 11-1-06; CR 09-062: cr. (11) and (12) Register April 2010 No. 652, eff. 5-1-10; CR 16-078: r. and recr. (7) (c), cr. (7) (d), am. (11) (a) Register January 2018 No. 745, eff. 2-1-18; correction in (7) (c) 2. made under s. 35.17, Stats., Register January 2018 No. 745; CR 22-015: am. (intro.), (2) (b), (8) Register June 2023 No. 810, eff. 7-1-23.

DHS 157.77 DHS 157.77 General purpose radiographic systems.

DHS 157.77(1) (1) Beam limitation.

DHS 157.77(1)(a) (a) Collimation. The useful beam shall be limited to the area of clinical interest. This requirement is met if a positive beam-limiting device meeting manufacturer’s specifications has been properly used or if evidence of collimation is shown on at least 3 sides or 3 corners of the film. Mammography systems are exempt from the collimation requirement.

DHS 157.77(1)(b) (b) General purpose stationary and mobile x-ray systems. General purpose stationary and mobile x-ray systems, including veterinary systems other than portable, shall meet both of the following requirements:

DHS 157.77(1)(b)1. 1. Only x-ray systems provided with means for independent stepless adjustment of at least 2 dimensions of the x-ray field may be used.

DHS 157.77(1)(b)2. 2. A method shall be provided for visually defining the perimeter of the x-ray field. The total misalignment of the edges of the visually defined field with the respective edges of the x-ray field along either the length or width of the visually defined field may not exceed 2% of the distance from the source to the center of the visually defined field when the surface upon which it appears is perpendicular to the axis of the x-ray beam.

DHS 157.77(1)(c) (c) Stationary general purpose x-ray systems. Stationary general purpose x-ray systems, both certified and non-certified, shall meet all the following requirements:

DHS 157.77(1)(c)1. 1. A method shall be provided to indicate when the axis of the x-ray beam is perpendicular to the plane of the image receptor, to align the center of the x-ray field with respect to the center of the image receptor to within 2% of the SID and to indicate the SID to within 2%.

DHS 157.77(1)(c)2. 2. The beam-limiting device shall indicate numerically the field size in the plane of the image receptor to which it is adjusted.

DHS 157.77(1)(c)3. 3. Field size dimensions and SIDs shall be specified in inches or centimeters and shall ensure that aperture adjustments result in x-ray field dimensions in the plane of the image receptor that correspond to those indicated by the beam-limiting device to within 2% of the SID when the beam axis is indicated to be perpendicular to the plane of the image receptor.

DHS 157.77(1)(d) (d) X-ray systems designed for one image receptor size. Radiographic equipment designed for only one image receptor size at a fixed SID shall be provided with means to limit the field at the plane of the image receptor to dimensions no greater than those of the image receptor, and to align the center of the x-ray field with the center of the image receptor to within 2% of the SID, or shall be provided with means to both size and align the x-ray field such that the x-ray field at the plane of the image receptor does not extend beyond any edge of the image receptor.

DHS 157.77(1)(e) (e) Miscellaneous and veterinary x-ray systems. X-ray systems other than those described in pars. (a) to (c), veterinary systems installed prior to the effective date of August 1, 2002, and all portable veterinary x-ray systems shall meet all of the following requirements:

DHS 157.77(1)(e)1. 1. Means shall be provided to limit the x-ray field in the plane of the image receptor so that such field does not exceed each dimension of the image receptor by more than 2% of the SID when the axis of the x-ray beam is perpendicular to the plane of the image receptor.

DHS 157.77(1)(e)2. 2. Means shall be provided to align the center of the x-ray field with the center of the image receptor to within 2% of the SID, or means shall be provided to both size and align the x-ray field such that the x-ray field at the plane of the image receptor does not extend beyond any edge of the image receptor. Compliance shall be determined with the axis of the x-ray beam perpendicular to the plane of the image receptor.

DHS 157.77(1)(e)3. 3. The requirements in subds. 1. and 2. may be met with a collimator system that meets the requirements for a general purpose x-ray system or, when alignment means are also provided, may be met with either of the following:

DHS 157.77(1)(e)3.a. a. An assortment of removable, fixed-aperture, beam-limiting devices sufficient to meet the requirement for each combination of image receptor size and SID for which the unit is designed with each such device having clear and permanent markings to indicate the image receptor size and SID for which it is designed.

DHS 157.77(1)(e)3.b. b. A beam-limiting device with multiple fixed apertures sufficient to meet the requirement for each combination of image receptor size and SID for which the unit is designed. Permanent, clearly legible markings shall indicate the image receptor size and SID that each aperture is designed for and shall indicate which aperture is in position for use.

DHS 157.77(2) (2) Radiation exposure control.

DHS 157.77(2)(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. In addition, exposure may not be initiated when the timer is set to a “zero” or “off” position if either position is provided.

DHS 157.77(2)(b) (b) Exposure indication. Means shall be provided for visual 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 157.77(2)(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. Except for dental panoramic systems, termination of an exposure shall cause automatic resetting of the timer to its initial setting or to “zero.”

DHS 157.77(2)(d) (d) Manual exposure control. An x-ray control shall be incorporated into each x-ray system so that the operator may terminate an exposure at any time except for any one of the following:

DHS 157.77(2)(d)1. 1. Exposure of 0.5 second or less.

DHS 157.77(2)(d)2. 2. During serial radiography when means shall be provided to permit completion of any single exposure of the series in process.

DHS 157.77(2)(e) (e) Automatic exposure controls. When an automatic exposure control is provided, it shall meet all the following requirements:

DHS 157.77(2)(e)1. 1. Indication shall be made on the control panel when this mode of operation is selected.

DHS 157.77(2)(e)2. 2. If the x-ray tube potential is equal to or greater than 50 kVp, the minimum exposure time for field emission equipment rated for pulsed operation shall be equal to or less than a time interval equivalent to 2 pulses.

DHS 157.77(2)(e)3. 3. The minimum exposure time for all equipment other than field emission equipment shall be equal to or less than one-sixtieth second or a time interval required to deliver 5 mAs, whichever is greater.

DHS 157.77(2)(e)4. 4. Either the product of peak x-ray tube potential, current, and exposure time shall be limited to not more than 60 kWs per exposure, or the product of x-ray tube current and exposure time shall be limited to not more than 600 mAs per exposure except that, when the x-ray tube potential is less than 50 kVp, the product of x-ray tube current and exposure time shall be limited to not more than 2000 mAs per exposure.

DHS 157.77(2)(e)5. 5. A visible signal shall indicate when an exposure has been terminated and manual resetting shall be required before further automatically timed exposures may be made.

DHS 157.77(2)(f) (f) Exposure duration linearity. For systems having independent selection of exposure time settings, the average ratios of exposure to the indicated timer setting, in units of .001mGy/s (mR/s), obtained at any 2 clinically used timer settings may not differ by more than 0.10 times their sum as expressed as:

(X1 - X2) < 0.1 (X1 + X2)

where X1 and X2 are the average .001 mGy/s (mR/s).

DHS 157.77(2)(g) (g) Exposure control location. The x-ray exposure control shall be placed so that the operator may view the patient while making any exposure and at least 1 meter (3.3 feet) from the end of the protective barrier.

DHS 157.77(2)(h) (h) Operator protection, except veterinary systems. X-ray systems, excluding veterinary systems, shall meet all the following requirements to protect the operator during system use, as applicable:

DHS 157.77(2)(h)1. 1. Stationary x-ray systems shall be required to have the x-ray control permanently mounted behind a protective barrier such that the operator is required to remain behind the protective barrier during the entire exposure.

DHS 157.77(2)(h)2. 2. Mobile and portable x-ray systems used continuously for greater than one week in the same location shall meet the requirements of stationary systems.

DHS 157.77(2)(h)3. 3. Mobile and portable x-ray systems used for less than one week at the same location shall be provided with either a protective barrier at least 2 meters (6.5 feet) high for operator protection during exposures or a means to allow the operator to be at least 2 meters (6.5 feet) from the tube housing assembly during the exposure.

DHS 157.77(2)(i) (i) Operator protection for veterinary systems. All stationary, mobile or portable x-ray systems used for veterinary work shall be provided with either a 2 meter (6.5 feet) high protective barrier for operator protection during exposures or a means to allow the operator to be at least 2 meters (6.5 feet) from the tube housing assembly during exposures. Persons within 2.7 meters (9 feet) of the tube or animal during exposures shall be protected with at least 0.25mm lead aprons. Persons restraining the animal during radiography shall be protected with at least 0.25mm lead aprons and full coverage gloves or full coverage mittens containing not less than 0.5mm lead equivalent material. The exposure control may be foot operated.

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.