Current through March 20, 2024
The requirements for therapeutic radiation machines of less
than 500 kilovolts (kV) are as follows.
006.01
LEAKAGE
RADIATION. When the x-ray tube is operated at its maximum rated
tube current for the maximum kilovolts (kV), the leakage air kerma rate must
not exceed the value specified at the distance specified for that
classification of therapeutic radiation machine as follows.
006.01(A)
0-50 KILOVOLT (KV)
SYSTEMS. The leakage air kerma rate measured at any position 5
centimeters from the tube housing assembly must not exceed 1 milligray (mGy) or
100 millirad (mrad) in any one hour.
006.01(B)
GREATER THAN 50 AND
LESS THAN 500 KILOVOLT (KV) SYSTEMS. The leakage air kerma rate
measured at a distance of 1 meter from the target in any direction must not
exceed 1 centigray (cGy) or 1 rad in any 1 hour. This air kerma rate
measurement may be averaged over areas no larger than 100 square centimeters.
In addition, the air kerma rate at a distance of 5 centimeters from the surface
of the tube housing assembly must not exceed 30 centigray (cGy) or 30 rad per
hour.
006.01(C)
DETERMINATION OF LEAKAGE RADIATION. For each
therapeutic radiation machine, the registrant must determine, or obtain from
the manufacturer, the leakage radiation existing at the positions specified in
180 NAC
20-006.01(A) and
20-006.01(B) for
the specified operating conditions. Records on leakage radiation measurements
must be maintained at the installation for inspection by the
Department.
006.02
PERMANENT BEAM LIMITING DEVICES. Permanent diaphragms
or cones used for limiting the useful beam must provide at least the same
degree of attenuation as required for the tube housing assembly.
006.03
ADJUSTABLE OR REMOVABLE
BEAM LIMITING DEVICES. Adjustable or removable beam limiting
devices must:
(A) Not transmit more than 5
percent of the useful beam for the most penetrating beam used for all
adjustable or removable beam limiting devices, diaphragms, cones or blocks;
and
(B) Indicate the position and
shape of the radiation field by a light beam when adjustable beam limiting
devices are used.
006.04
FILTER SYSTEM. The filter system must be marked so
that:
(A) Filters cannot be accidentally
displaced at any possible tube orientation;
(B) An interlock system prevents irradiation
if the proper filter is not in place for equipment installed after July 11,
2009;
(C) The air kerma rate
escaping from the filter slot does not exceed 1 centigray (cGy) or 1 rad per
hour at 1 meter under any operating conditions; and
(D) Each filter is marked regarding its
material of construction and its thickness.
006.05
TUBE
IMMOBILIZATION. The x-ray tube and housing must be immobilized as
follows.
006.05(A)
X-RAY
TUBE. The x-ray tube must be mounted so it cannot accidentally
turn or slide with respect to the housing aperture.
006.05(B)
TUBE HOUSING
ASSEMBLY. The tube housing assembly must be capable of being
immobilized for stationary portal treatments.
006.06
SOURCE
MARKING. The tube housing assembly must be marked so that it is
possible to determine the location of the source to within 5 millimeters. That
marking must be readily accessible for use during calibration
procedures.
006.07
BEAM
BLOCK. Contact therapy tube housing assemblies must have a
removable shield of material, equivalent in attenuation to 0.5 millimeters of
lead at 100 kilovolts (kV) that can be positioned over the entire useful beam
exit port during periods when the beam is not in use.
006.08
TIMER. A
suitable irradiation control device must be provided to terminate the
irradiation after a pre-set time interval. The timer must:
(A) Be provided at the treatment control
panel. The timer must have a display and must have a preset time selector and
an elapsed time or time remaining indicator;
(B) Be a cumulative timer that activates with
an indication of "BEAM-ON" and retains its reading after irradiation is
interrupted or terminated. After irradiation is terminated and before
irradiation can be reinitiated, it must be necessary to reset the elapsed time
indicator;
(C) The timer must
terminate irradiation when a pre-selected time has elapsed, if any dose
monitoring system present has not previously terminated irradiation;
(D) Permit accurate pre-setting and
determination of exposure times as short as 1 second;
(E) Not permit an exposure if the timer is
set at zero;
(F) Not activate until
the shutter is opened when irradiation is controlled by a shutter mechanism
unless calibration includes a timer error correction to compensate for
mechanical lag; and
(G) Be accurate
to within 1 percent of the selected value or 1 second, whichever is
greater.
006.09
CONTROL PANEL FUNCTIONS. The control panel, in
addition to the displays required by other provisions in 180 NAC 20-006, must
have:
(A) An indication of whether electrical
power is available at the control panel and if activation of the x-ray tube is
possible;
(B) An indication of
whether x-rays are being produced;
(C) A means for indicating x-ray tube
potential and current;
(D) A means
for terminating an exposure at any time;
(E) A locking device which will prevent
unauthorized use of the therapeutic radiation machine; and
(F) A positive display of specific filter or
filters in the beam for therapeutic radiation machines installed after July 11,
2009.
006.10
MULTIPLE TUBES. When a control panel can energize more
than one x-ray tube:
(A) It must be possible
to activate only one x-ray tube at any time;
(B) There must be an indication at the
control panel identifying which x-ray tube is activated; and
(C) There must be an indication at the tube
housing assembly when that tube is energized.
006.11
TARGET TO SKIN DISTANCE
(TSD). There must be a means of determining the central axis
target to skin distance (TSD) to within 1 centimeter and to reproduce this
measurement to within 2 millimeters from then on.
006.12
SHUTTERS.
Unless it is possible to bring the x-ray output to the prescribed exposure
parameters within 5 seconds after the x-ray "ON" switch is energized, the beam
must be attenuated by a shutter having a lead equivalency not less than that of
the tube housing assembly. In addition, after the unit is at operating
parameters, the shutter must be controlled by the operator from the control
panel. An indication of shutter position must appear at the control
panel.
006.13
LOW
FILTRATION X-RAY TUBES. Each therapeutic radiation machine
equipped with a beryllium or other low filtration window must have the tube
housing assembly clearly labeled and must be provided with a permanent warning
device on the control panel that is activated when no additional filtration is
present, to indicate that the dose rate is very high.
006.14
FACILITY DESIGN
REQUIREMENTS FOR THERAPEUTIC RADIATION MACHINES CAPABLE OF OPERATING IN THE
RANGE 50 KILOVOLTS (KV) TO 500 KILOVOLTS (KV). In addition to
shielding adequate to meet requirements of 180 NAC
20-009, the treatment room must meet
the following design requirements.
006.14(A)
AURAL COMMUNICATION. Provision must be made for
continuous two way aural communication between the patient and the operator at
the control panel.
006.14(B)
VIEWING SYSTEMS. Provision must be made to permit
continuous observation of the patient during irradiation. The viewing system
must be located so the operator can observe the patient from the control panel.
The therapeutic radiation machine must not be used for patient irradiation
unless at least one viewing system is operational.
006.15
ADDITIONAL
REQUIREMENTS. Treatment rooms that contain a therapeutic radiation
machine capable of operating above 150 kilovolts (kV) must meet the following
additional requirements.
006.15(A)
FIXED PROTECTIVE BARRIERS. All protective barriers
must be fixed except for entrance doors or beam interceptors.
006.15(B)
CONTROL
PANEL. The control panel must be located outside the treatment
room or in a totally enclosed booth, which has a ceiling, inside the
room.
006.15(C)
INTERLOCKS. Interlocks must be provided so all
entrance doors, including doors to any interior booths, must be closed before
treatment can be initiated or continued. If the radiation beam is interrupted
by any door opening, it must not be possible to restore the machine to
operation without closing the door and reinitiating irradiation by manual
action at the control panel.
006.15(D)
DOOR. When
any door referred to in 180 NAC 20-006.15, item (C) is opened while the x-ray
tube is activated, the air kerma rate at a distance of 1 meter from the source
must be reduced to less than 1 milligray (mGy) or 100 millirad (mrad) per
hour.
006.16
FULL CALIBRATION MEASUREMENTS. Full calibration
measurements must be performed as follows.
006.16(A)
FREQUENCY.
Full calibration of a therapeutic radiation machine subject to 180 NAC 20-006
must be performed by, or under the direct supervision of, a radiological
medical physicist:
(i) Before the first
medical use following installation or reinstallation of the therapeutic
radiation machine;
(ii) At
intervals not exceeding one year; and
(iii) Before medical use under the following
conditions:
(1) Whenever quality assurance
check measurements indicate that the radiation output differs by more than 5
percent from the value obtained at the last full calibration and the difference
cannot be reconciled; and
(2)
Following any component replacement, major repair, or modification of
components that could significantly affect the characteristics of the radiation
beam.
(iv) Apart from the
requirements of 180 NAC 20-006.16(A)(iii):
(1) Full calibration of therapeutic radiation
machines with multi energy capabilities is required only for those modes or
energies that are not within their acceptable range; and
(2) If the repair, replacement or
modification does not affect all energies, full calibration must be performed
on the affected energy that is in most frequent clinical use at the facility.
The remaining energies may be validated with quality assurance check procedures
compared to the criteria in 180 NAC
20-006.16(A),
item (iii)(1).
006.16(B)
REQUIRED
MEASUREMENTS. To satisfy the requirement of 180 NAC
20-006.16(A),
full calibration must include all measurements recommended for annual
calibration by the National Council on Radiation Protection and Measurements
(NCRP) Report 69, "Dosimetry of X-ray and Gamma Ray Beams for Radiation Therapy
in the Energy Range 10 keV to 50 MeV" (1981). This document is available for
viewing at the Department of Health and Human Services, Division of Public
Health, Office of Radiological Health, 301 Centennial Mall South, 3rd Floor,
Lincoln, Nebraska 68509.
006.16(C)
CALIBRATION RECORDS. The registrant must maintain a
record of each calibration for the duration of the registration. The record
must include:
(i) The date of the
calibration;
(ii) The
manufacturer's name;
(iii) Model
number and serial number for the therapeutic radiation machine if
applicable;
(iv) The model numbers
and serial numbers of the instruments used to calibrate the therapeutic
radiation machine; and
(v) The
signature of the radiological medical physicist responsible for performing the
calibration.
006.17
PERIODIC QUALITY ASSURANCE
CHECKS. The requirements for periodic quality assurance checks are
as follows.
006.17(A)
APPLICABILITY. Periodic quality assurance checks must
be performed on therapeutic radiation machines subject to 180 NAC 20-006 that
are capable of operation at greater than or equal to 50 kilovolts
(kV).
006.17(B)
QUALITY
ASSURANCE CHECK CONTENT. To satisfy the requirements of 180 NAC
20-006.17(A), quality assurance checks must meet the following requirements:
(i) Quality assurance checks must be
performed according to written procedures established by the radiological
medical physicist; and
(ii) The
quality assurance check procedures must specify the frequency the tests or
measurements are to be performed. The quality assurance check procedures must
specify that the quality assurance check will be performed during the
calibration specified in 180 NAC
20-006.16(A). The
acceptable tolerance for each parameter measured in the quality assurance
check, when compared to the value for that parameter established in the
calibration specified in 180 NAC
20-006.16(A),
must be specified.
006.17(C)
PARAMETER EXCEEDING
TOLERANCE. The cause for a parameter exceeding a tolerance set by
the radiological medical physicist must be investigated and corrected before
the system is used for patient irradiation.
006.17(D)
CHANGE IN OPERATING
CHARACTERISTICS. Whenever a quality assurance check indicates a
significant change in the operating characteristics of a system, as specified
in the radiological medical physicist's quality assurance check procedures, the
system must be recalibrated as required in 180 NAC
20-006.16(A).
006.17(E)
DOSIMETRY SYSTEM.
The registrant must use the dosimetry system described in 180 NAC
20-004.03(B), to
make the quality assurance check required in 180 NAC
20-006.17(B).
006.17(F)
RADIOLOGICAL MEDICAL
PHYSICIST REVIEW. The registrant must have the radiological
medical physicist review and sign the results of each radiation output quality
assurance check within 1 month of the date that the check was
performed.
006.17(G)
REQUIRED INTERVALS. The registrant must ensure that
quality assurance checks of therapeutic radiation machines subject to 180 NAC
20-006 are performed at intervals not to exceed 1 month.
006.17(H)
PROHIBITION. Despite the requirements of 180 NAC
20-006.17(F) and
(G), the registrant must ensure that no
therapeutic radiation machine is used to administer radiation to humans unless
the quality assurance checks required by 180 NAC
20-006.17(F) and
(G) have been performed within the 30 day
period immediately prior to that administration.
006.17(I)
PROPER
OPERATION. To satisfy the requirement of 180 NAC
20-006.17(B),
safety quality assurance checks must ensure proper operation of:
(i) Electrical interlocks at each external
beam radiation therapy room entrance;
(ii) The "BEAM-ON" and termination
switches;
(iii) Beam condition
indicator lights on the access door or doors, control console, and in the
radiation therapy room;
(iv)
Viewing systems; and
(v) If
applicable, electrically operated treatment room doors from inside and outside
the treatment room.
006.17(J)
RECORD
MAINTENANCE. The registrant must maintain a record of each quality
assurance check required by 180 NAC
20-006.17(A) and
(G) for three years. The record must include:
(i) The date of the quality assurance
check;
(ii) The manufacturer's
name, model number, and serial number of the therapeutic radiation
machine;
(iii) The manufacture's
name, model number and serial number for the instrument or instruments used to
measure the radiation output of the therapeutic radiation machine;
and
(iv) The signature of the
individual who performed the periodic quality assurance
check.
006.18
OPERATING PROCEDURES. The requirements for operation
procedures are as follows.
006.18(A)
PROHIBITION. The therapeutic radiation machine must
not be used for irradiation of patients unless the requirements of 180 NAC
20-006.16 and
20-006.17 have been met.
006.18(B)
SECURED IF
UNATTENDED. Therapeutic radiation machines must not be left
unattended unless secured according to 180 NAC 20-006.09, item(E).
006.18(C)
MECHANICAL SUPPORT OR
RESTRAINT. When a patient must be held in position for radiation
therapy, mechanical supporting or restraining devices must be used.
006.18(D)
HOLDER
PROTECTION. The tube housing assembly must not be held by an
individual during operation unless the assembly is designed to require such
holding and the peak tube potential of the system does not exceed 50 kilovolts
(kV). In those cases, the holder must wear protective gloves and a protective
apron of not less than 0.5 millimeters lead equivalency at 100 kilovolts
(kV).
006.18(E)
OPERATING AND EMERGENCY PROCEDURES. A copy of the
current operating and emergency procedures must be maintained at the
therapeutic radiation machine control console.
006.18(F)
INDIVIDUALS OTHER THAN
THE PATIENT. No individual other than the patient must be in the
treatment room during exposures from therapeutic radiation machines operating
above 150 kilovolts (kV). At energies less than or equal to 150 kilovolts (kV),
any individual, other than the patient, in the treatment room must be protected
by a barrier sufficient to meet the requirements of 180 NAC 4-005.
