Current through Bulletin 2024-06, March 15, 2024
In addition to the provisions of
R313-28-31,
R313-28-32 and
R313-28-35,
the requirements of this section apply to x-ray equipment and associated
facilities used for dental radiography. Criteria for extraoral dental
radiographic systems are covered in
R313-28-51,
R313-28-52
and
R313-28-53.
Intraoral dental radiographic systems used must meet the requirements of
R313-28-80.
(1) Source-to-Skin
distance (SSD). 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:
(a) 18 centimeters if operable above 50
kilovolts peak, or
(b) 10
centimeters if not operable above 50 kilovolts peak.
(2) Field limitation. Radiographic systems
designed for use with an intraoral image receptor shall be provided with means
to limit the x-ray field so that:
(a) if the
minimum source-to-skin distance (SSD) is 18 centimeters or more, the x-ray
field, at the minimum SSD, shall be containable in a circle having a diameter
of no more than seven centimeters; and
(b) if the minimum SSD is less than 18
centimeters, the x-ray field, at the minimum SSD, shall be containable in a
circle having a diameter of no more than six centimeters.
(3) Exposure Initiation.
(a) Means shall be provided to initiate the
radiation exposure by a deliberate action on the part of the operator, for
example, the depression of a switch. Radiation exposure shall not be initiated
without a deliberate action; and
(b) It shall not be possible to make an
exposure when the timer is set to a "zero" or "off" position if either position
is provided.
(4)
Exposure Termination.
(a) 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.
(b) An x-ray
exposure control shall be incorporated into x-ray systems so that an exposure
of more than 0.5 seconds can be terminated immediately by the
operator.
(c) Termination of an
exposure shall cause automatic resetting of the timer to its initial setting or
to "zero."
(5) Exposure
Indication. Means shall be provided for visual indication, observable 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.
(6) Timer Linearity.
For systems having independent selection of exposure time settings, the average
ratio of exposure to the indicated milliampere-seconds product obtained at two
consecutive timer settings or at two settings not differing by more than a
factor of two shall not differ by more than 0.10 times their sum.
(7) Exposure Control Location and Operator
Protection.
(a) Stationary x-ray systems
shall be required to have the x-ray exposure control mounted in a protected
area or a means to allow the operator to be at least 2.7 meters (9.0 feet) from
the tube housing assembly while making exposures; and
(b) Mobile and portable x-ray systems which
are:
(i) used for greater than one week in
the same location, for example, a room or suite, shall meet the requirements of
R313-28-80(7)(a); or
(ii) used for
less than one week in the same location shall be provided with either a
protective barrier at least two meters high for operator protection, or means
to allow the operator to be at least 2.7 meters (nine feet) from the tube
housing assembly while making exposures.
(8) Exposure Reproducibility. When all
technique factors are held constant, the coefficient of variation of exposure
shall not exceed 0.05 for certified x-ray systems or 0.10 for non-certified
x-ray systems. This requirement applies to clinically used
techniques.
(9) mA/mAs Linearity.
The following requirements apply when the equipment is operated on a power
supply as specified by the manufacturer for fixed x-ray tube potentials within
the range of 40 to 100 percent of the maximum rated potentials.
(a) For equipment having independent
selection of x-ray tube current, the average ratios of exposure to the
indicated milliampere-seconds product obtained at two consecutive tube current
settings or, when the tube current selection is continuous, two settings
differing by no more than a factor of two shall not differ by more than 0.10
times their sum.
(b) For 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 obtained at two consecutive mAs selector settings,
or when the mAs selector provides continuous selection, at two settings
differing by no more than a factor of two shall not differ by more than 0.10
times their sum.
(10)
Accuracy. Deviation of technique factors from indicated values shall not exceed
the limits specified for that system by its manufacturer. In the absence of
manufacturer's specifications the deviation shall not exceed ten percent of the
indicated value.
(11)
Administrative Controls.
(a) Patient and film
holding devices shall be used when the technique permits and holding is
required.
(b) The x-ray tube
housing and the position indicating device shall not be hand-held during an
exposure.
(c) The x-ray system
shall be operated so that the useful beam at the patient's skin does not exceed
the requirements of R313-28-80(2).
(d) Dental fluoroscopy without image
intensification shall not be used.
(12) Hand-held Portable Dental X-ray Systems.
(a) X-ray equipment designed to be hand-held
shall comply with Section
R313-28-31,
excluding Subsection
R313-28-31(5),
and with Section R313-28-80, excluding Subsections R313-28-80(7)(b) and
R313-28-80(11)(b).
(b) Protective
shielding of at least 0.5 millimeter lead equivalence shall be provided for the
operator to protect the operator's torso, hands, face, and gonads from
backscatter radiation. If the protective shielding is a backscatter shield
attached to the x-ray unit, the shield shall be positioned as close to the
patient as possible and the operator shall take care to remain in a protective
position.
(c) Portable radiation
machines designed to be hand-held are exempt from Subsection
R313-28-35(7).
The portable radiation machines shall be held by the tube housing support or
handle and shall be used in accordance with the manufacturer's operating
procedures.
(d) In addition to the
requirements of Subsection
R313-28-350(1),
each operator shall complete the training program supplied by the manufacturer
prior to using the x-ray unit. Records of training shall be maintained on file
for examination by an authorized representative of the Director.
