WAC 246-225A-060
General requirements for all dental
X-ray systems. Registrants shall use only dental X-ray
systems and medical X-ray systems for dental imaging that meet
the following requirements:
(1) The leakage radiation from the tube housing assembly,
measured at a distance of one meter in any direction from the
source, must not exceed 100 milliroentgens in one hour when
the X-ray tube is operated at its leakage technique factors. The department will determine compliance by measuring leakage
averaged over an area of 100 square centimeters with no
dimension of that area greater than 20 centimeters.
(2) The HVL of the useful beam for a given X-ray tube
potential must not be less than the values shown in Table 1 of
this section. To determine the HVL at an X-ray tube potential
which is not listed in Table 1 of this section, linear
interpolation or extrapolation may be made.
Table 1
Design
operating range
(kVp)
Measured
potential ( kVp)
HVL (millimeters
of aluminum
equivalent)
70 and below
70 and below
1.5
Above 70
71
2.1
80
2.3
90
2.5
100
2.7
(3) If two or more X-ray tubes are controlled by one
X-ray exposure button, the tube or tubes in operation must be
clearly marked before an exposure, on both the X-ray control
panel and near or on the selected tube housing assembly.
(4) The tube housing assembly supports of a stationary,
portable, or mobile X-ray system must be adjusted so that the
tube housing assembly remains stable and does not drift during
an exposure unless the tube housing movement during exposure
is a designed function of the X-ray system. Except for X-ray
systems specifically designed to be hand-held, an X-ray system
or tube housing assembly must not be hand-held by anyone
during the exposure.
(5) Except for CT X-ray systems that have a scram button,
each X-ray control must have a dead-man button.
(6) Technique indicators must be set as follows:
(a) All exposure technique factors must be set on the
control panel before the exposure begins, except when
automatic exposure controls are used. When automatic exposure
controls are used, any preselected settings for each exposure
must be indicated.
(b) On equipment having fixed technique factors, the
requirement in (a) of this subsection may be met by permanent
markings or labels.
(7) Linearity must be measured and met as follows:
(a) The difference between the ratio of milliroentgens
(mR) exposure to mAs at one mA or mAs setting and the ratio of
mR exposure to mAs at another mA or mAs setting must not
exceed 0.1 times the sum of the ratios. This is written as:
X1 - X2 ≤ 0.10 (X1 + X2)
Where X1 and X2 are the ratios (mR/mAs) for each mA or
mAs setting.
(b) The measurement must be performed at any selection of
mA or mAs without regard to focal spot size, provided neither
focal spot size is less than 0.45 millimeters.
(8) When four exposures are made at identical operating
settings, the difference between the maximum exposure (Emax)
and the minimum exposure (Emin) must be less than or equal to
ten percent of the average exposure (E). This is written as:
(Emax - Emin) ≤ 0.1E
(9) The difference between the kVp indicated on an X-ray
system and the measured kVp must not be greater than ten
percent of the indicated kVp.
(10) Timers must be able to:
(a) Stop the 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; and
(b) Reset automatically to the initial setting or to zero
when the exposure is stopped.
(11) X-ray equipment must not be capable of making an
exposure when the timer is set to the zero or off position if
either position is provided.
(12) Each X-ray control must have a visual indicator
(such as a light) or audible signal so that the operator knows
that X rays are being produced or the exposure is occurring or
has ended.
(13) Registrants shall not use dental fluoroscopy without
electronic amplification.