North Carolina Administrative Code
Title 10A - HEALTH AND HUMAN SERVICES
Chapter 15 - RADIATION PROTECTION
Section .0600 - X RAYS IN THE HEALING ARTS
Section 15 .0609 - X-RAY AND ELECTRON THERAPY INSTALLATIONS ONE MEV AND ABOVE
Universal Citation: 10A NC Admin Code 15 .0609
Current through Register Vol. 39, No. 6, September 16, 2024
(a) The requirements in Paragraphs (b) to (e) of this Rule shall apply only to medical facilities using medical x-ray and electron therapy equipment with energies one MeV and above. In addition, such medical facilities shall also comply with the requirements in Section.0900 of this Chapter.
(b) Equipment requirements are as follows:
(1) For existing
equipment and new equipment manufactured or installed after the effective date
of these Rules:
(A) The leakage radiation,
excluding neutrons, at a distance of one meter from the source shall not exceed
0.1 percent of the useful beam dose rate at one meter from the source for any
of its operating conditions.
(B)
Within one year after the effective date of these Rules the registrant shall
determine or obtain from the manufacturer for each machine the leakage
radiation specifications for electrons, x-rays and neutrons existing at the
points specified in Part (b)(1)(A) of this Rule for specified operating
conditions. Records on radiation leakage shall be maintained at the
installation.
(C) For equipment
from which neutron leakage may be a hazard, a qualified expert shall specify
such additional requirements as may be necessary to protect health or minimize
danger to life or property. The adequacy of these additional requirements shall
be confirmed by a survey. Survey records shall be maintained by the
registrant.
(2)
Adjustable or interchangeable beam limiting devices shall be provided and shall
meet the following requirements:
(A) For
existing equipment and new equipment manufactured or installed after the
effective date of these Rules:
(i) Adjustable
or interchangeable beam limiting devices shall attenuate the radiation incident
on the beam limiting devices such that the dose equivalent in rems at any
distance from the source does not exceed two percent of the maximum dose
equivalent in the useful beam measured at an equal distance from the radiation
source.
(ii) If the beam limiting
device does not meet the specifications in Subpart (b)(2)(A)(i) of this Rule,
the agency may accept auxiliary equipment or methods for accomplishing
attenuation.
(B) Dose
equivalent measurements may be averaged over an area up to but not exceeding
100 square centimeters at a distance of one meter from the target.
(3) In equipment which uses a
system of wedge filters, interchangeable field flattening filters or beam
scattering devices:
(A) Irradiation shall not
be possible until a selection of filter has been made at the treatment control
panel;
(B) An interlock system
shall be provided to prevent irradiation if the filter is not in the correct
position;
(C) An indication of the
orientation of the wedge filter with respect to the treatment field shall be
provided when wedge filters are used; and
(D) A display shall be provided at the
treatment control panel showing the filter(s) in use, including an indication
of "no filters".
(4)
Equipment installed after the effective date of these Rules shall be provided
with at least one radiation detector in the radiation head. This detector shall
be incorporated into a primary system.
(A)
Each primary system shall have a detector which is a transmission detector and
is a full beam detector and is placed on the patient side of any fixed added
filters other than a wedge filter;
(B) The detector(s) shall be removable only
with tools or shall be interlocked to prevent incorrect positioning.
(C) Each detector shall be capable of
independently monitoring and turning "off" the useful beam.
(D) 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.
(E) Each dose monitoring system shall have a
legible display at the treatment control panel which shall:
(i) maintain a reading until intentionally
reset;
(ii) in the event of power
failure, have the capability of retrieving the information displayed at the
time of failure.
(5) Selection and display of dose monitor
units shall comply with the following requirements:
(A) Irradiation shall not be possible until a
selection of a number of dose monitor units has been made at the treatment
control panel.
(B) After useful
beam termination, it shall be necessary to reset the preselected dose monitor
units before treatment can be reinitiated.
(C) The preselected number of dose monitor
units shall be displayed at the treatment control panel until reset for the
next irradiation.
(6)
Automatic termination of irradiation by the dose monitoring system shall comply
with the following requirements:
(A) Each of
the monitoring systems shall be capable of independently terminating
irradiation. Provisions shall be made to test the correct operation of each
system.
(B) Each primary system
shall terminate irradiation when the preselected number of dose monitor units
have been reached, and each secondary system shall be used as a
backup.
(7) It shall be
possible to terminate irradiation and equipment movements or to go from an
interruption condition to termination conditions at any time from the treatment
control panel.
(8) It shall be
possible to interrupt irradiation and equipment movements at any time from the
treatment control panel. Following an interruption it shall be possible to
restart irradiation by operator action without any reselection of operating
conditions. If any change is made of a pre-selected value during an
interruption the equipment shall go to termination condition.
(9) A timer shall be provided and shall meet
the following requirements:
(A) The timer
shall have a display at the treatment control panel. The timer shall have a
preset time selector and an elapsed time indicator.
(B) The timer shall be a cumulative timer
which switches "on" and "off" with the radiation and retains its reading after
irradiation is interrupted or terminated. It shall be necessary to zero the
elapsed time indicator and the preset time selector after irradiation is
terminated, before reactivation is possible.
(C) To guard against failure of the dose
monitoring systems, the timer shall terminate irradiation when a preselected
time has elapsed.
(10)
In equipment capable of both x-ray therapy and electron therapy:
(A) Irradiation shall not be possible until a
selection of radiation type, x-rays or electrons, has been made at the
treatment control panel;
(B) An
interlock system shall be provided to prevent irradiation if any selected
operations carried out in the treatment room do not agree with the selected
operations carried out at the treatment control panel;
(C) An interlock system shall be provided to
prevent irradiation with x-rays when electron applicators are fitted and
irradiation with electrons when x-ray wedge filters are fitted; and
(D) The radiation type selected shall be
displayed at the treatment control panel before and during
irradiation.
(11) In
equipment capable of generating radiation beams of different energies:
(A) Irradiation shall not be possible until a
selection of energy has been made at the treatment control panel;
(B) An interlock system shall be provided to
insure that the equipment emits primarily the energy of radiation which has
been selected;
(C) An interlock
system shall be provided to prevent irradiation if any selected operations
carried out in the treatment room do not agree with the selected operations
carried out at the treatment control panel; and
(D) The energy selected shall be displayed at
the treatment control panel before and during irradiation.
(12) In equipment capable of both
stationary-beam therapy and moving-beam therapy:
(A) Irradiation shall not be possible until a
selection of stationary-beam therapy or moving-beam therapy has been made at
the treatment control panel;
(B) An
interlock system shall be provided to prevent irradiation if any selected
operations carried out in the treatment room do not agree with the selected
operations carried out at the treatment control panel;
(C) An interlock system shall be provided to
terminate irradiation if the movement stops during moving-beam
therapy;
(D) Moving-beam therapy
shall be so controlled that the required dose monitor units per degree of
rotation is obtained; and
(E) The
mode of operation shall be displayed at the treatment control panel.
(13) The registrant shall
determine or obtain from the manufacturer the location with reference to an
accessible point on the radiation head of:
(A)
the x-ray target and the virtual source of x-rays;
(B) the electron window or the scattering
foil; and
(C) all possible
orientations of the useful beam.
(14) Means shall be provided so that all
radiation safety interlocks can be checked. When preselection of any of the
operating conditions requires action in the treatment room and at the treatment
control panel selection at one location shall not give a display at the other
location until the requisite selection operations in both locations have been
completed.
(c) Facility shielding shall be adequate to meet the requirements of Section.1600 of this Chapter.
(d) Facility design shall meet the following requirements:
(1) Except
for entrance doors, all required barriers shall be fixed barriers.
(2) The control panel shall be located
outside the treatment room. The door must be closed during radiation
production.
(3) A viewing 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. When the viewing system is by
electronic means (e.g., television), an alternate viewing system shall be
available.
(4) Provision shall be
made for two-way aural communication with the patient from the control room,
however, where excessive noise levels make aural communication impractical,
other methods of communication shall be used.
(5) Treatment rooms to which access is
possible through more than one entrance shall be provided with warning lights,
in a readily observable position near the outside of all access doors,
preferably at eye level, which will indicate when the useful beam is
"on".
(6) Have all entrance doors
to the treatment room electrically connected such that the x-ray production
cannot be initiated unless all doors are closed and shall cease if any door is
opened during x-ray production.
(e) The operating procedures which follow are in addition to those in Rule.0908 of this Chapter.
(1) Radiation protection surveys shall comply
with the following requirements:
(A) All new
facilities and existing facilities not previously surveyed shall have a
radiation protection survey made by, or under the direction of, a qualified
expert. This shall also be done after any change in the facility or equipment
which might cause a significant increase in radiation hazard.
(B) The expert shall report his findings in
writing to the person in charge of the facility, and a copy of the report shall
be transmitted by the registrant to the agency at the address in Rule.0111 of
this Chapter.
(2) No
person other than the patient shall be in the treatment room during treatment.
When a patient must be held in position for radiation therapy, mechanical
supporting or restraining devices shall be used.
(3) The output of each therapeutic x-ray
machine shall be calibrated by, or under the direct supervision of a qualified
expert, before it is first used for medical purposes. Calibrations shall be
repeated at least once every 12 months and after any change which might
significantly increase radiation hazards. Calibration of the therapy beam shall
be performed with measurement instruments, the calibration of which is
traceable to national standards for exposure or absorbed dose and which shall
have been calibrated within the preceding 12 months. Records of calibrations
shall be provided to and maintained by the registrant. The calibration shall
include at least the following determinations:
(A) the exposure rate or dose rate as
appropriate for the field sizes used and for each effective energy and for each
treatment distance used for radiation therapy;
(B) the beam quality (e.g., half-value layer
when appropriate) for every proposed combination of operating conditions used
for radiation therapy;
(C) the
congruence between the radiation field and the field indicated by the localized
device when used;
(D) verification
that the equipment is operating in compliance with the design specifications
concerning the light localizer, the side light and backpointer alignment with
the isocenter, when applicable, variation in the axis of rotation for the
table, gantry and jaw system and beam flatness and symmetry in air or at the
specified depths in a water phantom.
(4) Spot checks shall be performed monthly.
(A) The spot check methods shall be in
writing and shall be designed by a qualified expert.
(B) Whenever a spot check indicates a
significant change (as specified in the qualified expert's spot check design)
in the operating characteristics of a machine, the machine shall be
recalibrated as required in Subparagraph (e)(3) of this Rule.
(C) A log shall be kept of all spot check
measurements.
Authority
G.S.
104E-7;
104E-12(a);
Eff. February 1, 1980;
Amended Eff. January 1, 1994; November 1,
1989;
Transferred and Recodified from
15A NCAC
11.0609 Eff. February 1,
2015.
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