902 KAR 100:136.
Therapeutic systems below one (1) MeV.
RELATES TO: KRS
211.842-211.852, 211.990(4)
STATUTORY
AUTHORITY: KRS 194.050, 211.090, 211.844
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 kilovoltage 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 kilovoltage 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 intercompared 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. (3
Ky.R. 570; eff. 3-2-77; Am. 12 Ky.R. 1402; eff. 3-4-86; 18 Ky.R. 1559; eff.
1-10-92.)
