Current through Register Vol. 51, No. 3, September 1, 2024
RELATES TO: KRS 211.842-211.850,
211.990(4)
NECESSITY, FUNCTION, AND CONFORMITY: The Cabinet for Human
Resources is authorized by
KRS
211.844 to provide by 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 and
electron systems which operate at energies of one (1) MeV and above.
Section 1. Applicability. This administrative
regulation shall apply to therapeutic x-ray and electron systems which operate
at energies of one (1) MeV and above and to persons, equipment and materials
used in connection with the possession, use or operation of these
systems.
Section 2. Leakage
Radiation to the Patient Area.
(1) Systems
registered after March 2, 1977 shall meet the following requirements:
(a) For operating conditions producing
maximum leakages the absorbed dose in rads due to leakage radiation (including
electrons, x-rays and neutrons) at a point in a circular plane of radius two
(2) meters centered on and perpendicular to the central axis of the beam at the
isocenter or normal treatment distance and outside the maximum useful beam
shall not exceed one-tenth (0.1) percent of the maximum absorbed dose in rads
of the unattenuated useful beam measured at the point of intersection of the
central axis of the beam and the plane surface. Measurements, excluding those
for neutrons, shall be averaged over an area up to but not exceeding 100 square
centimeters at the position specified. Measurements of the portion of the
leakage radiation dose contributed by neutrons shall be averaged over an area
up to but not exceeding 200 square centimeters; and
(b) The registrant shall determine or obtain
from the manufacturer, for each system, the leakage radiation existing at the
points specified in paragraph (a) of this subsection for specified operating
conditions. Records of radiation leakage shall be maintained at the
installation.
(2)
Systems registered before March 2, 1977, shall meet the following requirements:
(a) For operating conditions producing
maximum leakage radiation, the absorbed dose rate in rads due to leakage
radiation (excluding neutrons) at a point on the area specified in subsection
(1)(a) of this section shall not exceed one-tenth (0.1) percent of the maximum
absorbed dose in rads of the unattenuated useful beam dose rate at one (1)
meter from the source, for its operating conditions. Measurements shall be
averaged over an area up to but not exceeding 100 square centimeters;
and
(b) The registrant shall
determine or obtain from the manufacturer for each system the leakage radiation
existing at the points specified in subsection (1)(a) of this section for the
specified operating conditions. Records of radiation leakage shall be
maintained at the installation.
(3) If neutron leakage may be a hazard the
cabinet may, by specific order, impose upon a user additional requirements, as
it deems appropriate or necessary to protect health and minimize danger to life
or property. If imposing additional requirements, the cabinet shall give due
consideration to accepted standards of safe practice.
Section 3. Leakage Radiation Outside the
Patient Area. The leakage radiation outside the patient area shall meet the
following requirements:
(1) The absorbed dose
in rads due to leakage radiation, except in the area defined in Section 2(1)(a)
of this administrative regulation, measured at one (1) meter from the path of
the charged particle, before the charged particle strikes the target or window,
shall not exceed one-tenth (0.1) percent for x-ray leakage, nor .05 percent for
neutron leakage of the maximum absorbed dose in rads of the unattenuated useful
beam measured at the point of intersection of the central axis of the beam and
the circular plane specified in Section 2(a) of this administrative regulation;
and
(2) The registrant shall
determine or obtain from the manufacturer the actual leakage radiation existing
at the points specified in Section 2(1)(a) of this administrative regulation
for specific operating conditions. Measurements, excluding neutrons, shall be
averaged over an area up to but not exceeding 100 square centimeters. Neutron
measurements shall be averaged over an area up to but not exceeding 200 square
centimeters.
Section 4.
Beam Limiting Devices. Adjustable or interchangeable beam limiting devices
shall be provided so that the following requirements are met:
(1) Adjustable or interchangeable beam
limiting devices shall transmit no more than two (2) percent of the useful beam
at the normal treatment distance for the portion of the useful beam which is to
be attenuated by the beam limiting device. Neutrons are not included in this
requirement;
(2) If the beam
limiting device on existing equipment does not meet the requirements of
subsection (1) of this section the cabinet may accept auxiliary equipment or
methods for accomplishing attenuation; and
(3) Dose equivalent measurements shall be
averaged over an area up to but not exceeding 100 square centimeters at a
distance of one (1) meter from the target. If overlapping beam limiting devices
are present, the leakage through each set shall be measured
independently.
Section
5. Filters. Filters shall be provided so that the following
requirements are met:
(1) If the absorbed dose
rate information provided in Section 17 of this administrative regulation
relates exclusively to operation with a field flattening or beam scattering
filter in place, then the filter shall be a permanent filter only removable by
the use of tools; and
(2) In
therapy systems which use a system of wedge filters or interchangeable field
flattening filters or beam scattering filters the following requirements shall
be met:
(a) Irradiation shall not be possible
until a selection of filter has been made at the control panel;
(b) An interlock system shall be provided to
prevent irradiation if the filter is not in the correct position; and
(c) A display shall be provided at the
control panel showing the filter(s) (or zero filter) in use.
Section 6. Beam
Quality. The beam quality for therapy systems shall meet the following
requirements:
(1) The absorbed dose, from
x-ray stray radiation in the useful electron beam, on the central axis of the
beam at a depth ten (10) cm further than the practical range shall not exceed
the following limits:
(a) Three (3) percent of
the maximum absorbed dose for electron beam energies to fifteen (15)
MeV;
(b) Five (5) percent of the
maximum absorbed dose for electron beam energies in the range fifteen (15) to
thirty-five (35) MeV;
(c) Ten (10)
percent of the maximum absorbed dose for electron beam energies in the range
thirty-five (35) MeV to fifty (50) MeV;
(d) Twenty (20) percent of the maximum
absorbed dose for electron beam energies fifty (50) MeV or greater;
and
(e) Linear interpolation shall
be used for values not stated.
(2) The measurements required by subsection
(1) of this section shall be made at electron beam maximum size not exceeding
fifteen (15) by fifteen (15) cm in a phantom whose cross-sectional dimensions
exceed the measurement radiation field by at least five (5) cm and whose depth
is sufficient to perform the required measurement. The incident surface of the
phantom shall be at the normal treatment distance and normal to the central
axis of the beam.
(3) At the
largest field size available, the absorbed dose from electron stray radiation
in the useful x-ray beam, at the surface during x-ray irradiation on the
central axis of the beam shall not exceed the following limits;
(a) Eighty (80) percent of the maximum
absorbed dose for x-ray beam maximum energies in the range of one (1) to two
(2) MeV;
(b) Seventy (70) percent
of the maximum absorbed dose for x-ray beam maximum energies in the range of
two (2) to five (5) MeV;
(c) Sixty
(60) percent of the maximum absorbed dose for x-ray beam maximum energies in
the range of five (5) to fifteen (15) MeV;
(d) Fifty (50) percent of the maximum
absorbed dose for x-ray beam maximum energies in the range of fifteen (15) to
thirty-five (35) MeV;
(e) Forty
(40) percent of the maximum absorbed dose for x-ray beam maximum energies in
the range of thirty-five (35) through fifty (50) MeV; and
(f) Linear interpolation shall be used for
values not stated.
(4)
The measurements required by subsection (3) of this section shall be made using
a phantom of size and placement which meet the requirements of subsection (2)
of this section. An instrument which allows extrapolation to the surface
absorbed dose shall be used. Beam modifying devices which are removed without
the use of tools, except beam scattering or field flattening filters, shall be
removed from the useful beam.
(5)
The registrant shall determine, or obtain from the manufacturer, the maximum
percentage absorbed dose in the useful beam due to neutrons, excluding stray
neutron radiation for specified operating conditions.
Section 7. Beam Monitors. Systems registered
after March 2, 1977 shall be provided with two (2) radiation detectors in the
radiation head. The two (2) detectors shall be incorporated into two (2) dose
monitoring systems. Systems registered before March 2, 1977 shall be provided
with at least one (1) radiation detector in the radiation head. This detector
shall be incorporated into a primary dose monitoring system. Beam monitoring
systems shall meet the following requirements:
(1) The detectors shall be removable only
with tools and shall be interlocked to prevent incorrect positioning.
(2) Each detector shall be capable of
independently monitoring, interrupting, and terminating the useful
beam;
(3) Each detector shall form
part of a dose monitoring system from whose readings in dose monitor units the
absorbed dose at a reference point in the treatment volume can be
calculated;
(4) For systems
registered after March 2, 1977 the design of the dose monitoring systems of
subsection (4) of this section shall ensure that the malfunctioning of one (1)
system shall not affect the correct functioning of the second system. In
addition the failure of an element which may be common to both systems shall
terminate the useful beam; and
(5)
Each dose monitoring system shall have a legible display at the control panel.
Each display shall also meet the following requirements:
(a) Maintain a reading until intentionally
reset to zero;
(b) In the event of
power failure, have the capability of retrieving the information displayed in
at least one (1) system for twenty (20) minute period of time after failure
occurs;
(c) On systems registered
after March 2, 1977 the display shall have only one (1) scale and no scale
multiplying factors; and
(d) A
design shall be utilized so that increasing dose is displayed by increasing
numbers and shall be so designed that in the event of an overdosage of
radiation the absorbed dose may be accurately determined.
Section 8. Beam Symmetry. The
useful beam shall be symmetrical within the following requirements:
(1) For systems registered after March 2,
1977 and inherently capable of producing useful beams with a symmetry exceeding
five (5) percent. The asymmetry of the radiation beam in two (2) orthogonal
directions shall be monitored before the beam passes through the beam limiting
device. Means shall be provided so that, if the difference in the dose rate
between one (1) region and another region symmetrically displaced from the
central axis of the beam exceeds five (5) percent of the central axis dose
rate, indication of this condition is made at the control panel; and if this
difference exceeds ten (10) percent, the irradiation is terminated;
and
(2) On systems registered
before March 2, 1977 if the cabinet has determined that beam symmetry is
inadequate the use of an automatic beam asymmetry warning system shall be
required.
Section 9.
Selection and Display of Dose Monitor Units. Irradiation shall not be possible
until a selection of a number of dose monitor units has been made at the
control panel. In addition dose monitor units shall also meet the following
requirements:
(1) After the useful beam
terminates it shall be necessary to reset the preselected dose monitor units
before treatment can be reinitiated;
(2) The preselected number of dose monitor
units shall be displayed at the control panel until manually reset for the next
irradiation; and
(3) For systems
registered after March 2, 1977, it shall be necessary to manually reset the
preselected dose monitor units before radiation can be initiated.
Section 10. Termination of
Irradiation by the Dose Monitoring System or Systems During Stationary Beam
Therapy. Each of the required dose monitoring systems shall terminate
irradiation when the preselected number of dose monitor units has been detected
by the system. Dose monitoring systems shall also meet the following
requirements:
(1) Each primary system shall
terminate irradiation when the preselected number of dose monitor units has
been detected by the system.
(2) If
the original design of the equipment included a second dose monitoring system,
that system shall be capable of terminating irradiation when not more than
fifteen (15) percent of forty (40) dose monitor units above the preselected
number of dose monitor units set at the control panel has been detected by the
second dose monitoring system; and
(3) For systems registered after March 2,
1977 the beam shall terminate automatically when the secondary system detects
more than ten (10) percent or twenty-five (25) dose monitor units above the
preset dose monitor units and indicators on the central panel shall show which
system has terminated the beam.
Section 11. Termination Switches. It shall be
possible to terminate irradiation and equipment movement or to go from an
interruption condition to termination conditions at once from the control
panel.
Section 12. Interruption
Switches. It shall be possible to interrupt irradiation and equipment movements
at once from the control panel. Following an interruption if shall be possible
to restart irradiation by operator action without reselection of operating
conditions. If a change is made of a preselected value during interruption the
system shall go to termination condition.
Section 13. Timers. A timer shall be
provided, have a display at the control panel, a preset time selector and an
elapsed time indicator. The timer shall be a cumulative timer which switches on
and off with the irradiation and retains its reading after irradiation is
interrupted or terminated. If shall be necessary to zero the elapsed time
indicator after irradiation is terminated. To guard against failure of the dose
monitoring systems, the timer shall terminate irradiation when a preselected
time has elapsed.
Section 14.
Selection of Radiation Type. In systems capable of both x-ray and electron
therapy the following requirements shall be met:
(1) Irradiation shall not be possible until a
selection of radiation type (x-ray or electrons) has been made at the control
panel;
(2) An interlock system
shall be provided to ensure that the system can emit only the radiation type
which has been selected;
(3) An
interlock system shall be provided to prevent irradiation if selected
operations carried out in the treatment room do not agree with the selected
operations carried out at the control panel;
(4) An interlock system shall be provided to
prevent irradiation with x-ray except to obtain a port film if electron
applicators are fitted and irradiation with electrons if accessories specific
for x-ray therapy are fitted; and
(5) The radiation type shall be displayed at
the control panel before and during irradiation.
Section 15. Selection of Energy. In systems
capable of generating radiation beams of different energies the following
requirements shall be met:
(1) Irradiation
shall not be possible until a selection of energy has been made at the control
panel;
(2) An interlock system
shall be provided to prevent irradiation if selected operations carried out in
the treatment room do not agree with the selected operations carried out at the
control panel;
(3) The nominal
energy value selected shall be displayed at the control panel before and during
irradiation; and
(4) For equipment
registered after the effective date of these administrative regulations, an
interlock system shall be provided to terminate irradiation if the energy of
the electrons striking the x-ray target or electron window deviates by more
than twenty (20) percent or three (3) MeV, whichever is smaller, from the
selected nominal energy.
Section
16. Selection of Stationary Beam Therapy or Moving Beam Therapy.
In systems capable of both stationary and moving beam therapy the following
requirements shall be met:
(1) Irradiation
shall not be possible until a selection of stationary or moving beam therapy
has been made at the control panel;
(2) An interlock system shall be provided to
ensure that the system can operate only in the mode which has been
selected;
(3) An interlock system
shall be provided to prevent irradiation if selected operations carried out in
the treatment room do not agree with the selected operations carried out at the
control panel;
(4) The mode of
operation shall be displayed at the control panel;
(5) For equipment registered after the
effective date of this administrative regulation, an interlock system shall be
provided to terminate irradiation if movement of the gantry occurs during
stationary beam therapy or movement of the gantry stops during moving beam
therapy unless stoppage is a preplanned function.
(6) Moving beam therapy shall be controlled
to obtain the selected relationships between incremental dose monitor units and
incremental angle of movement. Additionally for units registered after the
effective date of this administrative regulation:
(a) An interlock system, shall be provided to
terminate irradiation if the number of dose monitor units delivered in ten (10)
degrees of arc differs by more than twenty (20) percent from the selected
value; and
(b) Where gantry angle
terminates the irradiation in arc therapy, the dose monitor units shall differ
by less than five (5) percent from the value calculated from the absorbed dose
per unit angle relationship.
(7) Where the dose monitor system terminates
the irradiation in arc therapy, the termination of irradiation shall be
required by Section 10 of this administrative regulation.
Section 17. Absorbed Dose Rate. In systems
registered after March 2, 1977 a system shall be provided from whose readings
the absorbed dose rate at a reference point in the treatment volume can be
calculated. The radiation detectors specified in Section 7 of this
administrative regulation may form part of this system. In addition the
following requirements shall be met:
(1) The
dose monitor units shall be displayed at the control panel; and
(2) If the system can deliver an absorbed
dose rate at the normal treatment distance more than twice the maximum value
specified by the manufacturer for machine parameters utilized, a device shall
be provided which terminates irradiation if the dose rate exceeds a value not
more than twice the specified maximum. The value at which the irradiation is
terminated shall be a record maintained by the registrant.
Section 18. Location of Virtual Source and
Beam Orientation. The registrant shall determine or obtain from the
manufacturer the location with reference to an accessible point on the
radiation head the following points:
(1) The
x-ray target or the virtual source of x-rays; and
(2) The electron window or the virtual source
of electrons if the system has electron beams capabilities.
Section 19. System Checking
Facilities. Facilities shall be provided so that radiation safety interlocks
can be checked. If preselection of operating conditions requires action in the
treatment room and at the control panel, selection at one (1) location shall
not give a display at the other location until the requisite selected
operations in both locations have been completed.
Section 20. Auxiliary Support of Patients. If
a patient is required to be held in position for radiation therapy, mechanical
supporting or restraining devices shall be used. No person other than the
patient shall be in the treatment room during irradiation.
Section 21. Facility and Shielding
Requirements. In addition to shielding adequate to meet the requirements of
902 KAR 100:105,
the following requirements shall be met:
(1)
Except for entrance doors and beam interceptors the required barriers shall be
fixed barriers;
(2) The control
panel shall be located outside the treatment room;
(3) Windows, mirror systems, closed-circuit
television viewing screens or other equivalent viewing systems 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 viewing system is by electronic means (e.g.,
television) an alternate viewing system shall be provided for use in the event
of failure of the primary system;
(4) Provision shall be made for two (2) way
aural communication with the patient from the control station. However, if
excessive noise levels or treatment requirements make aural communication
impractical, other methods of communications shall be used;
(5) The treatment room shall be so
constructed that persons may be able to escape from within;
(6) Treatment room entrances to which access
is possible through more than one (1) entrance, shall be provided with warning
lights in a readily observable position near the outside of access doors, which
indicate if the useful beam is "on." These warning lights shall be accompanied
by an appropriate sign as specified in 902 KAR 100:020, Section 12;
and
(7) Interlocks shall be
provided so that entrance doors shall be closed before treatment can be
initiated or continued. If the radiation beam is interrupted by a door opening,
it shall be possible to restore the machine to operation only by closing the
door and reinitiating exposure by manual action at the control panel.
Section 22. Protection Survey. New
facilities, and existing facilities not previously surveyed, shall have a
radiation protection survey made by, or under the direction of a qualified
expert. The survey shall also be conducted after a change in the facility which
might produce a radiation hazard.
(1) The
registrant shall obtain a written report of the survey and a copy of the report
shall be transmitted by the registrant to the cabinet within thirty (30) days
of receipt of the report.
(2) The
survey and report shall indicate instances where the facility in the opinion of
the qualified expert is in violation of the applicable therapy radiation
administrative regulations and shall cite the sections violated.
Section 23. Calibrations. The
output of each therapeutic x-ray system shall be calibrated by a qualified
expert, before it is first used for medical purposed. Calibrations shall be
repeated at least once every twelve (12) months and after changes which might
significantly increase radiation hazards. Calibration of the therapy beam shall
be performed with a measurement instrument having a calibration factor for
cobalt - sixty (60) gamma rays, and which shall have been calibrated within the
preceding two (2) years and after servicing that may have affected its
calibration. Records of calibrations shall be maintained by the registrant for
five (5) years after completion of the full calibration. The records shall be
in sufficient detail that the dose at a reference point in soft tissue may be
calculated to within an uncertainty of five (5) percent. A copy of the latest
calibration shall be available in the area of the control panel. The
calibration shall include at least the following determinations:
(1) Verification that the system is operating
in compliance with the design specifications concerning the light localizer,
the side light and back-pointer alignment with the isocenter, if applicable,
variation in the axis of rotation for the table, gantry, and jaw system, and
beam flatness and symmetry at the specific depths;
(2) The absorbed dose rate at various depths
of water for the range of and field sizes used and for each effective energy
that verifies the accuracy of the dosimetry of therapy procedures utilized with
that therapy beam;
(3) In
uniformity of the radiation field an its dependence upon the direction of the
useful beam;
(4) Verification that
existing depth-dose data and isodose charts applicable to the specific machine
continue to be valid or are updated to existing machine conditions;
and
(5) Verification of
transmission and electron buildup factors for accessories, i.e., wedges, shadow
trays and compensators.
Section
24. Spot Checks. A spot check shall be made monthly and shall
include carefully selected representative or indicative measurements which
demonstrate the consistency of relevant system operating characteristics, or
lack of same. Spot checks shall meet the following requirements:
(1) The spot check methods shall be in
writing, shall have been designed by a qualified expert and a copy of the
procedure shall be submitted to the cabinet prior to its
implementation;
(2) If a qualified
expert does not perform the spot check measurements, the results of the spot
check measurements shall be reviewed by the qualified experts within fifteen
(15) days;
(3) The spot check
procedures shall specify the frequency at which tests or measurements are to be
performed and the acceptable tolerance for each parameter measured in the spot
check when compared to the value for that parameter determined in the
calibration;
(4) At intervals not
to exceed one (1) week, spot checks shall be made of absorbed dose measurements
at a minimum of two (2) depths in a phantom;
(5) If a spot check indicates a significant
change (as specified in the qualified experts spot check design) in the
operating characteristics of a system, the system shall be recalibrated as
required by Section 23 of this administrative regulation;
(6) If a system has a built in device which
provides a self-check of parameters during irradiation, the measurement shall
not be utilized as a spot check measurement;
(7) The course for a parameter exceeding a
tolerance set by the qualified expert shall be investigated and corrected
before the system is used for patient irradiation;
(8) Records of spot check measurements shall
be maintained by the registrant for a period of two (2) years after completion
of the spot check measurements and necessary corrective actions; and
(9) If a spot check involves a radiation
measurement, the measurement shall be obtained using a system meeting the
requirements of Section 23 of this administrative regulation or which has been
intercompared with a system meeting those requirements within the previous
year.
STATUTORY AUTHORITY:
KRS 194.050,
211.090,
211.844
