Current through Register Vol. 43, No. 52, December 26, 2024
In addition to
K.A.R.
28-35-242a and
28-35-242b, this regulation shall
apply to all X-ray equipment and the associated facilities used for dental
radiography. The requirements for extraoral dental radiographic systems shall
be those requirements specified in
K.A.R.
28-35-244a. Each registrant shall use only
systems meeting the requirements of this regulation.
(a) Source-to-skin distance (SSD). X-ray
systems designed for use with an intraoral image receptor shall be provided
with a means to limit the SSD to not less than either of the following:
(1) 18 centimeters if operable above 50 kVp;
or
(2) 10 centimeters if operable
at 50 kVp only.
(b) kVp
limitations. Dental X-ray machines with a nominal fixed kVp of less than 50 kVp
shall not be used to make diagnostic dental radiographs of humans.
(c) Beam limitation. Each radiographic system
designed for use with an intraoral image receptor shall be provided with a
means to limit the X-ray beam so that the beam at the minimum SSD is
containable in a circle with a diameter of no more than seven centimeters.
(d) Radiation exposure control.
(1) Exposure initiation.
(A) A means shall be provided to initiate the
radiation exposure by a deliberate action on the part of the operator,
including the depression of a switch. Radiation exposure shall not be initiated
without such an action.
(B) When
the timer is set to a "zero" or "off" position, if either position is provided,
an exposure shall not be possible.
(2) Exposure indication. A means shall be
provided for a 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.
(3) Exposure termination.
(A) A means shall be provided to terminate
each exposure at a preset time interval, a 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 each X-ray system so that each exposure can
be terminated by the operator at any time, except for exposures of one-half
second or less.
(C) Each
termination of an exposure shall cause the automatic resetting of the timer to
its initial setting or to "zero."
(4) Exposure duration or timer linearity. For
each system that provides for the independent selection of exposure time
settings, the average ratios (X1) of exposure to the indicated timer setting,
in units of C kg-1 s-1 (mR/s), obtained at any two clinically used time
settings shall not differ by more than 0.10 times their sum. The linearity is
calculated using the following equation:
(X1-X2) < 0.10 (X1 + X2)
where X1 and X2 are the average ratios of exposure to the
indicated timer setting.
(5) Exposure control location and operator
protection.
(A) Each stationary X-ray system
shall be required to have the X-ray exposure control permanently mounted in a
protected area so that the operator is required to remain in that protected
area during the entire exposure.
(B) Each mobile or portable X-ray system used
for one week or longer in the same location, including a room or suite, shall
meet the requirements of this regulation.
(C) Each mobile or portable X-ray system used
for less than one week in the same location shall be provided either with a
protective barrier that is at least two meters (6.5 feet) high for operator
protection or with the means to allow the operator to be at least 2.7 meters (9
feet) from the tube housing assembly while making exposures.
(e) Reproducibility.
When the equipment is operated with an adequate power supply as specified by
the manufacturer, the estimated coefficient of variation of radiation exposures
shall be no greater than 0.05 for any specific combination of selected
technique factors.
(f) mA and mAs
linearity. The requirements specified in this subsection shall apply when the
equipment is operated with a power supply as specified by the manufacturer for
any fixed X-ray tube potential within the range of 40 percent to 100 percent of
the maximum rated mA or mAs.
(1) Equipment
that provides for the independent selection of X-ray tube current (mA). The
average ratios (X1) of exposure to the indicated milliampere-seconds product,
in units of C kg-1 mAs-1 (or mR/mAs), obtained at any two consecutive tube
current settings shall not differ by more than 0.10 times their sum. The
linearity is calculated using the following equation:
X1-X2 < 0.10 (X1 + X2)
where X1 and X2 are the average values obtained at each of two
consecutive tube current settings, or at two settings differing by no more than
a factor of two if the tube current selection is continuous.
(2) Equipment that has a combined X-ray tube
current-exposure time project (mAs) selector but not a separate tube current
(mA) selector. The average ratios (X1) of exposure to the indicated
milliampere-seconds product, in units of C kg-1 mAs-1 (or mR/mAs), obtained at
any two consecutive mAs selector settings shall not differ by more than 0.10
times their sum. The linearity is calculated using the following equation:
X1-X2 < 0.10 (X1 + X2)
where X1 and X2 are the average values obtained at any two mAs
selector settings, or at two settings differing by no more than a factor of two
if the mAs selector provides continuous selection.
(3) Measuring compliance. Determination of
compliance shall be based on 10 exposures taken within one hour, at each of two
settings. These two settings may include any two focal spot sizes, unless one
is equal to or less than 0.45 millimeters and the other is greater than 0.45
millimeters. For purposes of this regulation, "focal spot size" shall mean the
nominal focal spot size specified by the X-ray tube manufacturer.
(g) Accuracy. The deviation of
technique factors from the indicated values for kVp and exposure time, if time
is independently selectable, shall not exceed the limits specified for that
system by its manufacturer. In the absence of manufacturer's specifications,
the deviation shall not exceed 10 percent of the indicated value for kVp and 20
percent for time.
(h)
Administrative controls.
(1) Patient-holding
and film-holding devices shall be used when the techniques permit.
(2) The tube housing and the position
indication device (PID) shall not be handheld during an exposure.
(3) Each X-ray system shall be operated so
that the useful beam at the patient's skin does not exceed the requirements of
this regulation.
(4) Dental
fluoroscopy without image intensification shall not be used.
