Current through Register Vol. 51, No. 3, September 1, 2024
RELATES TO: KRS 211.842-211.852,
211.990(4)
NECESSITY, FUNCTION, AND CONFORMITY: The Cabinet for Human
Resources is authorized by
KRS
211.844 to provide by administrative
regulation for the registration and licensing of the possession or use of
sources of ionizing or electronic product radiation and the handling, and
disposal of radioactive waste. The purpose of this administrative regulation is
to provide special requirements for the possession, use, and operation of
therapeutic x-ray systems which operate at energies below one (1) MeV.
Section 1. Applicability. This administrative
regulation shall apply to therapeutic x-ray systems which operate at energies
below one (1) MeV and to persons, equipment and materials used in connection
with the possession, use or operation of the systems.
Section 2. Leakage Radiation. If the x-ray
system is operated at its leakage technique factors, the leakage radiation
shall not exceed the value given below:
(1)
For contact therapy systems the leakage radiation shall not exceed 100
milliroentgens per hour measured five (5) cm anywhere from the tube
housing;
(2) For systems operating
between zero and 150 kVp and which are registered prior to March 2, 1977, the
leakage radiation shall not exceed one (1) roentgen in one (1) hour at one (1)
meter from the source;
(3) For
systems operating between zero and 150 kVp and which are registered after March
2, 1977, the leakage radiation shall not exceed 100 milliroentgens in one (1)
hour at one (1) meter from the source;
(4) For systems operating between 151 and 500
kVp the leakage radiation shall not exceed one (1) roentgen in one (1) hour at
one (1) meter from the source; or
(5) For systems operating between 501 and 999
kVp the leakage radiation at one (1) meter from the source shall not exceed
one-tenth (0.1) percent of the useful beam one (1) meter from the
source.
Section 3.
Permanent Beam Limiting Devices. Permanent fixed diaphragms or cones used for
collimating the useful beam shall provide the same or higher degree of
protection as required by the tube housing assembly.
Section 4. Removable Beam Limiting Devices.
Removable beam limiting devices shall, for the portion of the useful beam to be
blocked by these devices, transmit not more than one (1) percent of the useful
beam at the maximum kilovoltage and maximum treatment filter. This requirement
does not apply to auxiliary blocks or materials placed in the useful beam to
shape the useful beam to the individual patient.
Section 5. Adjustable Beam Limiting Devices.
Adjustable beam limiting devices shall meet the following requirements:
(1) Devices installed after March 2, 1977
shall, for the portion of the useful beam to be blocked by these devices,
transmit not more than one (1) percent of the original beam at the maximum
kilo-voltage and maximum treatment filter; or
(2) Devices installed before March 2, 1977,
shall for the portion of the useful beam to be blocked by these devices,
transmit not more than five (5) percent of the original beam at the maximum
kilo-voltage and maximum treatment filter.
Section 6. Filter System. The filter system
shall be designed to meet the following requirements:
(1) The filters cannot be accidentally
displaced at possible tube orientation;
(2) Each filter shall be marked as to its
material of construction and its thickness and, for wedge filters, the wedge
angle shall appear on the wedge or wedge tray; and
(3) The radiation at five (5) centimeters
from the filter insertion slot opening does not exceed thirty (30) roentgens
per hour under operating conditions.
Section 7. Focal Spot Marking and Assembly
Immobilization. The tube housing assembly shall be marked so that it is
possible to determine the location of the focal spot to within five (5)
millimeters and the marking shall be readily accessible for use during
calibration procedures. In addition the assembly shall be capable of being
immobilized during stationary treatments.
Section 8. Contact Therapy Beam Block.
Contact therapy tube housing assemblies shall have a removable shield of at
least five-tenths (0.5) mm lead equivalent material at 100 kVp that can be
positioned over the entire useful beam port during periods that the beam is not
in use.
Section 9. Beam Monitor
System. Therapy x-ray systems registered after March 2, 1977 which are capable
of operating above 150 kVp shall be provided with a beam monitoring system
which meets the following requirements:
(1)
The beam monitoring system shall have a detector interlock to prevent incorrect
positioning;
(2) The beam
monitoring system shall have a display at the control panel from which the dose
at a reference point in soft tissue can be calculated;
(3) The control panel display shall maintain
the administered dose reading until intentionally reset to zero;
(4) If a system malfunctions or electrical
power failure occurs the dose administered to a patient prior to the system's
malfunction or power failure can be accurately determined;
(5) The beam monitoring system shall not
allow irradiation until a preselected value of exposure has been made at the
treatment control panel;
(6) The
beam monitoring system shall be capable of independently terminating
irradiation if the preselected exposure has been reached; and
(7) The control panel display shall not have
scale multiplying factors and shall utilize a design that displays increasing
dose by increasing numbers.
Section
10. Timers. Therapeutic x-ray systems shall be provided with
timers which meet the following requirements:
(1) The timer shall have a display at the
control panel with a preset time selector and an elapsed time
indicator;
(2) The timer shall be a
cumulative timer which activates with the production of radiation and retains
its reading after irradiation is interrupted or terminated. It shall be
necessary to zero the elapsed time indicator after irradiation is terminated
and before irradiation can be reinstated.
(3) The timer shall terminate irradiation
after a preselected time has elapsed if a dose monitoring system present has
not previously terminated irradiation.
(4) The timer shall permit accurate
presetting and determination of exposure times as short as one (1) second and
shall not permit an exposure if set at zero; and
(5) The timer shall not activate until the
shutter is open if the irradiation is controlled by a shutter
mechanism.
Section 11.
Control Panel. The control panel, in addition to other display requirements of
this administrative regulation, shall meet the following requirements:
(1) The control panel shall indicate the
presence of electrical power, the possibility of tube activation, the
production of x-rays, and the actual kilovoltage and current across the
tube;
(2) A means shall be provided
for terminating an exposure at once;
(3) A locking device shall be provided which
prevents unauthorized use of the x-ray system; and
(4) A display shall be provided on systems
registered after March 2, 1977 which indicates specific filter(s) in the useful
beam.
Section 12.
Control Panels Which Control More Than One (1) Tube. If a control panel may
energize more than one (1) x-ray tube then the following requirements shall be
met:
(1) Only one (1) x-ray tube may be
activated at one (1) time;
(2) The
control panel shall indicate which x-ray tube is energized; and
(3) Each x-ray tube shall indicate whether
that tube is energized.
Section
13. Source-to-skin Distance. A means shall be provided to
determine the source-to-skin distance to within one (1) centimeter.
Section 14. Shutter Control. Unless it is
possible to bring the x-ray output to the prescribed exposure parameters within
five (5) seconds, the entire useful beam shall be automatically attenuated by a
shutter having a lead equivalency not less than that of the tube housing.
Systems using shutter control shall meet the following requirements:
(1) The shutter shall be electrically
controlled by the operator from the control panel; and
(2) An indication of shutter position shall
appear at the control panel. The control panel shall indicate whether the
shutter is open or closed.
Section
15. Facility Design and Shielding Requirements for X-ray Systems
Capable of Operating Above Fifty (50) kVp. In addition to the shielding
adequate to meet the requirements of
902 KAR 100:105,
the following requirements shall also be met:
(1) Provision shall be made for two (2) way
aural communication with the patient from the control room; however, if
excessive noise levels make aural communication impractical other methods of
communication shall be used;
(2)
Windows, mirror systems, or closed-circuit television viewing screens or an
equivalent system shall be provided to permit continuous observation of the
patient during irradiation and shall be so located that the operator may see
the patient and the control panel from the same position. If the primary
viewing system is by electronic means (e.g., television) an alternate viewing
system shall be available as a back-up if electronic failure occurs;
(3) The therapy room shall be so constructed
that persons may be able to escape from within; and
(4) Facilities which contain an x-ray system
which may be operated above 150 kVp shall meet the following requirements:
(a) Protective barriers shall be fixed
barriers, except for entrance doors or beam interceptors.
(b) The control panel shall be located
outside the treatment room;
(c)
Doors of the treatment room shall be electrically connected to the control
panel so that x-ray production cannot occur unless the door is
closed;
(d) Doors referred to in
paragraphs (a) and (c) of this subsection, shall be interlocked electrically so
that they are closed before treatment can be initiated or continued. If the
irradiation is interrupted by a door opening, it shall not be possible to
restore the machine to operation without closing the door and reinitiating
irradiation by manual action at the control panel; and
(e) If a door referred to in paragraph (d) of
this subsection is opened while the x-ray tube is activated, the exposure at a
distance of one (1) meter from the source shall be reduced to less than 100
milliroentgens per hour.
Section 16. Surveys and Calibrations. New
facilities and existing facilities not previously surveyed, shall have a
radiation protection survey made by or under the direction of a qualified
expert. A survey shall also be conducted after changes in the facility which
might cause a significant increase in a radiation hazard.
(1) The registrant shall obtain a written
report of this survey from the qualified expert and a copy of this report shall
be transmitted by the registrant to the cabinet within thirty (30) days of
receipt of the report. The survey and report shall indicate instances where the
installation, in the opinion of the qualified expert, is in noncompliance of
applicable administrative regulations.
(2) The calibration of an x-ray system shall
be performed at intervals not to exceed one (1) year and after changes or
replacement of components which are likely to change the radiation output. This
calibration shall be performed by or under the direction of a qualified expert
who is physically present at the facility during the calibration. Calibration
of the radiation output shall be performed with a calibrated dosimetry system
which is directly traceable to national standards and which shall have been
calibrated within the preceding two (2) years. Records of calibrations shall be
maintained by the registrant for five (5) years. The calibration shall include
at least the following determinations:
(a)
Verification that the system is operating in compliance with the design
specifications;
(b) The exposure
rate as a function of field size, technique factors, filter, and treatment
distance used;
(c) The congruence
between the radiation field and field indicated by the localizing device if
localizing devices are used for radiation therapy; and
(d) The uniformity of the largest radiation
field used.
(3) The
calibration determinations prescribed in subsection (2) of this section shall
be performed in a manner that the dose at a reference point in soft tissue can
be calculated within plus or minus five (5) percent of the intended absorbed
dose.
(4) A copy of the most recent
x-ray system calibration shall be available at or in the area of the control
panel.
(5) Therapeutic x-ray
systems capable of operation at greater than 150 kVp shall also have spot
checks performed which meet the following:
(a)
The spot check procedures shall specify the frequency at which tests or
measurements are to be performed. The spot check procedures shall specify that
the spot check shall be performed during the calibration specified in
subsection (2) of this section. The acceptable tolerance for each parameter
measured in the spot check compared to the value for that parameter determined
in the calibration specified in subsection (2) of this section shall be
stated;
(b) The spot check methods
shall be in writing and shall have been designed by a qualified expert. A copy
of the procedures shall be submitted to the cabinet prior to its
implementation;
(c) If a qualified
expert does not perform the spot check measurement, the results of the spot
check measurements shall be reviewed by a qualified expert within fifteen (15)
days;
(d) If a spot check indicates
a significant change in the operating characteristics of a machine, the machine
shall be recalibrated as required by subsection (2) of this section;
(e) Records of spot check measurements shall
be maintained for two (2) years after completion of the spot check measurements
and necessary corrective actions;
(f) The spot check procedures shall specify
the frequency at which tests of measurements are to be performed the spot check
procedures shall specify that the spot check shall be performed during the
calibration specified in subsection (2) of this section shall be
stated;
(g) The cause for a
parameter exceeding a tolerance set by the qualified expert shall be
investigated and corrected before the system is used for patient irradiation;
and
(h) If a spot check involves a
radiation measurement, the measurement shall be obtained using a system
satisfying the requirements of subsection (2) of this section or which has been
intercom-pared with a system meeting those requirements within the previous
year.
Section
17. Operating Procedures. Therapeutic x-ray systems shall be
operated so the following requirements are met:
(1) The facility shall be operated in
compliance with any limitations indicated by the radiation protection survey
which have been approved by the cabinet;
(2) The x-ray system shall not be used in the
administration of radiation therapy unless the requirement of Section 16 of
this administrative regulation has been met;
(3) Therapeutic x-ray systems shall not be
left unattended unless the locking device required by Section 10(3) of this
administrative regulation is set to prevent activation of the useful
beam;
(4) If a patient is required
to be held in position for radiation therapy, mechanical supporting or
restraining devices shall be used;
(5) The tube housing assembly shall not be
held by hand during operation unless the system is designed to require holding
and the potential difference of the system does not exceed fifty (50) kVp. In
this instance the holder shall wear protective gloves and apron of not less
than five-tenths (0.5) mm lead equivalency at 100 kVp;
(6) No individual other than the patient
shall be in the treatment room unless the individual is protected by a barrier
sufficient to meet the requirements of 902 KAR 100:020. No individual other
than the patient shall be in the treatment room during exposures from x-ray
systems operating above 150 kVp; and
(7) The x-ray system shall not be used in the
administration of radiation therapy unless the requirements of subsections (2)
and (5)(d) of this section have been met.
STATUTORY AUTHORITY:
KRS 194.050,
211.090,
211.844
