North Carolina Administrative Code
Title 10A - HEALTH AND HUMAN SERVICES
Chapter 15 - RADIATION PROTECTION
Section .0600 - X RAYS IN THE HEALING ARTS
Section 15 .0608 - THERAPEUTIC X-RAY INSTALLATIONS: LESS THAN ONE MEV
Universal Citation: 10A NC Admin Code 15 .0608
Current through Register Vol. 39, No. 6, September 16, 2024
(a) Unless specifically provided otherwise by the rules in this Chapter, the requirements in this Rule shall apply only to therapeutic x-ray installations which are not capable of operating at or above one MeV. Therapeutic x-ray equipment subject to the provisions of this Rule shall comply with the following requirements:
(1) When the tube is operated at its leakage
technique factors, the leakage radiation in any direction shall not exceed the
value specified at the distance specified for the classification of that x-ray
system.
(A) For contact therapy systems, the
leakage radiation shall not exceed 100 mR/hr at five centimeters from the tube
housing.
(B) Systems operating from
zero to 150 kVp which are manufactured or installed prior to the effective date
of this Rule shall have a leakage radiation which does not exceed one R in one
hour at one meter from the source.
(C) Systems operating from zero to 150 kVp
which are manufactured on or after the effective date of this Rule shall have a
leakage radiation which does not exceed 100 mR in one hour at one meter from
the source.
(D) Systems operating
from 151 to 999 kVp shall have leakage radiation which does not exceed one R in
one hour at one meter from the source, except systems which operate in excess
of 500 kVp may have a leakage radiation in one hour at one meter from the
source equivalent to 0.1 percent of the exposure in the useful beam in one hour
at a distance of one meter from the source.
(2) Permanent beam limiting devices used for
collimating the useful beam shall provide the same or higher degree of
protection as that required by the tube housing assembly.
(3) Adjustable or removable beam limiting
devices shall transmit not more than five percent of the useful beam as
determined at the maximum tube potential and maximum treatment
filter.
(4) The filter system shall
be so designed that:
(A) Filters cannot be
accidentally displaced from the useful beam at any tube orientation;
(B) Each filter is marked as to its material
of construction and its thickness or wedge angle for wedges;
(C) It shall be possible for the operator to
determine the presence of and identify each filter and the orientation of each
wedge filter in the useful beam when the operator is positioned at the control
panel either by display at the control panel or by direct
observation;
(D) The filters and
filter insertion slot opening shall be so designed that the radiation at five
centimeters from the filter insertion slot opening does not exceed 30 roentgens
per hour under all operating conditions; and
(E) Each machine equipped with a beryllium or
other low filtration window shall be clearly labeled as such upon the tube head
housing and upon the control panel.
(5) The tube housing assembly shall be
immobilized during stationary treatments.
(6) The tube housing assembly shall be so
marked that it is possible to determine the location of the focal spot to
within five millimeters and such marking shall be readily accessible.
(7) Equipment of greater than 150 kVp
installed after the effective date of this Rule shall be provided with a beam
monitor system.
(8) The exposure
timer shall meet the following requirements:
(A) A timer shall be provided which has a
display at the treatment control panel. The timer shall have a preset time
selector and shall terminate irradiation when a preselected time has
elapsed.
(B) The timer shall switch
on and off with the radiation and retain its reading after irradiation is
interrupted or terminated.
(9) The control panel shall have:
(A) an indication of whether electrical power
is present and activation of the x-ray tube is possible;
(B) an indication of whether x-rays are being
produced;
(C) the means for
indicating kVp and x-ray tube current;
(D) the means for terminating an exposure at
any time;
(E) a locking device
which will prevent unauthorized use of the x-ray system and, for systems not
having a lock at the control panel, an alternate method of preventing
unauthorized use, shall be provided;
(F) for equipment manufactured after the
effective date of this Rule, a positive display of specific filter(s) in the
beam.
(10) When a
control panel may energize more than one x-ray tube:
(A) It shall be possible to activate only one
x-ray tube during any one time interval;
(B) There shall be an indication at the
control panel identifying which x-ray tube can be energized; and
(C) There shall be an indication at the x-ray
tube if that tubehead can be energized.
(11) There shall be means of determining the
target to patient distance to within one centimeter.
(12) If exposures are controlled by a timer,
that timer:
(A) shall permit the setting of
exposure times at least as short as one second, and
(B) shall not permit an exposure if set at
zero or "off".
(13)
Unless it is possible to bring the x-ray exposure rate to its prescribed value
within five seconds of actuating the x-ray "on" control, the tube housing shall
be fitted with a shutter operable only from the control panel, and of lead
equivalent not less than that of the tube housing. In addition:
(A) The status of the shutter "Beam On",
"Beam Off" or "Shutter Open", "Shutter Closed" or equivalent description, shall
be indicated at the control panel.
(B) It shall not be possible to initiate an
exposure sequence unless the shutter has first been placed in the "Beam Off" or
"Shutter Closed" position.
(C) The
shutter shall automatically go to the "Beam Off" or "Shutter Closed" position
if the exposure is terminated by:
(i) the
operation of the timer,
(ii) the
dose monitoring system, if provided,
(iii) the operation of a safety interlock,
or
(iv) a power failure.
(b) In addition to shielding adequate to meet requirements of Section.1600 of this Chapter, the following treatment room design requirements shall be met:
(1) Treatment room entrances shall be
provided with warning lights in a readily observable position, which will
indicate when the useful beam is "on".
(2) Provision shall be made for two-way
communication with the patient from the control room.
(3) A 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.
(4) Facilities which
contain an x-ray system which may be operated above 150 kVp shall:
(A) have all necessary shielding, except for
any beam interceptor, provided by fixed barriers;
(B) have the control panel in a protected
area which is outside the treatment room;
(C) 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;
(D) if the radiation
output of the x-ray tube is affected by any door opening, be so designed that
it is possible to initiate x-ray production only by:
(i) closing all doors and,
subsequently,
(ii) reinitiating the
exposure by manual action at the control panel.
(c) Operating procedures, surveys, and calibration shall comply with the following requirements:
(1) 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 which might produce a radiation hazard. The
expert shall report his findings in writing to the person in charge of the
facility, and a copy of this report shall be transmitted by the registrant to
the agency at the address in Rule.0111 of this Chapter.
(2) The radiation output of each therapeutic
x-ray machine shall be calibrated by, or under the direction of a qualified
expert who is physically present at the facility during the calibration
procedure. The calibration shall be repeated after any change, in or
replacement of, components of the x-ray generating equipment which could cause
a change in x-ray output. Calibration of the therapy beam shall be performed
with a measurement instrument, 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 radiation outputs shall
be provided to and maintained by the registrant.
(3) Each therapeutic x-ray machine shall be
calibrated as described in Subparagraph (c)(2) of this Rule at time intervals
not exceeding one year. The calibration shall include at least the following
determinations:
(A) the accurate
determination of the air exposure rate or the dose rate at a reference point
within a suitable phantom, as appropriate;
(B) the congruence between the radiation
field and light localizer, when such is used;
(C) the half-value layer for every
combination of kVp and filter used for radiation therapy.
(4) Therapeutic x-ray systems capable of
operation at greater than 150 kVp, in addition to the annual calibration
required in Subparagraphs (c)(2) and (3) of this Rule, shall have spot checks
performed.
(A) The spot check methods and
frequency shall be designed and in writing by a qualified expert. Spot checks
shall include verification of continued congruency between the radiation field
and the localizing device where an optical field illuminator is used.
(B) Whenever a spot check indicates a
significant change in the operating characteristics of a machine, as specified
in the qualified expert's spot check design, the machine shall be recalibrated
as required.
(C) A log shall be
kept of all spot check measurements.
(5) Therapeutic x-ray machines shall not be
left unattended unless the locking device required by Part (a)(10)(E) of this
Rule is set to prevent activation of the useful beam.
(6) Except as provided in Rule.0603(a)(1)(H)
of this Section, no individual other than the patient shall be in the treatment
room during exposures unless he is protected by a barrier sufficient to meet
the requirements of Rule.1604 of this Chapter, and no individual other than the
patient shall be in the treatment room when the kVp exceeds 150 during
exposures.
(7) The tube housing
assembly shall not be held by hand during operation unless the system is
designed to require such holding and the peak tube potential of the system does
not exceed 50 kVp. In such cases the holder shall wear protective gloves and
apron of not less than 0.5 mm lead equivalency at 100 kVp.
Authority
G.S.
104E-7;
104E-12(a);
Eff. February 1, 1980;
Amended Eff. January 1, 1994; May 1, 1992;
November 1, 1989;
Transferred and Recodified from
15A NCAC
11.0608 Eff. February 1,
2015.
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