Wis. Admin. Code Department of Health Services DHS 157.78 - Intraoral dental radiographic systems
(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.
(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:
(a) 20 centimeters (8 inches) if operable
above 50 kVp. Beam-limiting devices shall be lead lined.
(b) 10 centimeters (4 inches) if operable at
50 kVp only. Beam-limiting devices shall be lead lined.
(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.
(4) RADIATION EXPOSURE
CONTROL. Intraoral radiographic systems shall meet all of the following
exposure control requirements:
(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.
(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.
(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.
(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:
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.
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.
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.
(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.
(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:
(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 tha
n 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.
(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.
(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.
(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.
(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.
(9) ADMINISTRATIVE CONTROLS.
(a) Intraoral image receptor devices shall be
used.
(b) The tube housing and the
cone may not be hand-held during an exposure.
(c) The tube shall be stationary during
exposure, except for panoramic systems. Any oscillation of the tube head shall
cease before exposure is made.
(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:
(a) For all uses:
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.
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.
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.
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.
(b) For permanent facilities:
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.
2. Hand-held intraoral dental radiographic
units may not be used for patient examinations in hallways and waiting
rooms.
Notes
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