(1) Warning label.
The control panel containing the main power switch shall bear the following
warning statement, legible and accessible to view: "WARNING: This x-ray unit
may be dangerous to patient and operator unless safe exposure factors and
operating instructions are observed."
(2) Battery charge indicator. On
battery-powered x-ray generators, visual means shall be provided on the control
panel to indicate whether the battery is in a state of charge adequate for
proper operation.
(3) Leakage
radiation from the diagnostic source assembly. The leakage radiation from the
diagnostic source assembly measured at a distance of one meter in any direction
from the source may not exceed one mGy (115 milliroentgens) in one hour when an
x-ray tube is operated at its leakage technique factors. Compliance shall be
determined by measurements averaged over an area of 100 square centimeters with
no linear dimension greater than 20 centimeters. Leakage technique factors may
be any of the following:
(a) For diagnostic
source assemblies intended for capacitor energy storage equipment, the
maximum-rated peak tube potential and the maximum-rated number of exposures in
an hour for operation at the maximum-rated peak tube potential with the
quantity of charge per exposure being 10 millicoulombs, which is 10 mAs, or the
minimum obtainable from the unit, whichever is larger.
(b) For diagnostic source assemblies intended
for field emission equipment rated for pulsed operation, the maximum-rated peak
tube potential and the maximum-rated number of x-ray pulses in an hour for
operation at the maximum-rated peak tube potential.
(c) For all other diagnostic source
assemblies, the maximum-rated peak tube potential and the maximum-rated
continuous tube current for the maximum-rated peak tube
potential.
(4) Radiation
from components other than the diagnostic source assembly. The radiation
emitted by a component other than the diagnostic source assembly may not exceed
20m Gy (2.15 milliroentgens) in one hour at 5 centimeters from any accessible
surface of the component when it is operated in an assembled x-ray system under
any conditions for which it was designed. Compliance shall be determined by
measurements averaged over an area of 100 square centimeters with no linear
dimension greater than 20 centimeters.
(5) Beam quality.
(a) The half-value layer of the useful beam
for a given x-ray tube potential may not be less than the values shown in Table
DHS 157.75. If it is necessary to determine the half-value layer at an x-ray
tube potential that is not listed in Table
DHS 157.75, linear interpolation or
extrapolation may be made.
Table DHS 157.75
Half-Value Layer Requirements
|
X-Ray Tube Voltage in kilovolt peak
|
Half-Value Layer in mm Aluminum
|
|
Design Operating Range
|
Mesured Operating Potential
|
Specified Dental
Systems1
|
I-Other X-Ray
Systems2
|
II-Other Diagnostic X-Ray Systems
3
|
|
Below 51
|
30
40
50
|
1.5
1.5
1.5
|
0.3
0.4
0.5
|
0.3
0.4
0.5
|
|
51 to 70
|
51
60
70
|
1.5
1.5
1.5
|
1.2
1.3
1.5
|
1.3
1.5
1.8
|
|
Above 70
|
71
80
90
100
110
120
130
140
150
|
2.1
2.3
2.5
2.7
3.0
3.2
3.5
3.8
4.1
|
2.1
2.3
2.5
2.7
3.0
3.2
3.5
3.8
4.1
|
2.5
2.9
3.2
3.6
3.9
4.3
4.7
5.0
5.4
|
1 Dental x-ray systems designed
for use with intraoral image receptors and manufactured after December 1,
1980.
2 Dental x-ray systems designed
for use with intraoral image receptors and manufactured before or on December
1, 1980, and all other x-ray systems subject to
21 CFR
1020 and manufactured before June 10,
2006.
3 All x-ray systems, except
dental x-ray systems designed for use with intraoral image receptors, subject
to 21 CFR
1020 and manufactured on or after June 10,
2006.
(b) For x-ray systems
using capacitor discharge to provide power to an x-ray tube, half-value layer
shall be determined with the system fully charged and a setting of 10 mAs for
each exposure.
(c) The required
minimal half-value layer of the useful beam shall include the filtration
contributed by all materials that are permanently between the source and the
patient.
(d) For x-ray systems with
variable filtration controls, the system shall prevent an exposure unless the
appropriate filtration is in place for the kilovolts peak selected.
(6) Multiple tubes. When 2 or more
radiographic tubes are controlled by one exposure switch, the tube that has
been selected shall be clearly indicated prior to initiation of the exposure.
The indication shall be both on an x-ray control panel and at or near the
selected tube housing assembly.
(7)
Mechanical support of tube head. The tube housing assembly supports shall be
adjusted such that the tube housing assembly will remain stable during an
exposure unless tube-housing movement is a designed function of an x-ray
system.
(8) Technique indicators.
(a) The technique factors to be used during
an exposure shall be indicated before the exposure begins. If automatic
exposure controls are used, the technique factors, which are set prior to the
exposure, shall be indicated.
(b)
The requirement in par. (a) may be met by permanent markings on equipment
having fixed technique factors. Indication of technique factors shall be
visible from the operator's position except in the case of spot films made by
the fluoroscopist.
(9)
Maintaining compliance. Diagnostic x-ray systems and their associated
components used on humans and certified under the federal x-ray equipment
performance standard, 21 CFR
1020, shall be maintained in compliance with
applicable requirements of that standard.
(10) Locks. All position locking, holding and
centering devices on x-ray system components and systems shall function as
intended.
