Current through Register 1531, September 27, 2024
(A)
Leakage
Radiation. When the x-ray tube is operated at its maximum rated
tube current for the maximum kV, the leakage air kerma rate shall not exceed
the value specified at the distance specified for that classification of
therapeutic radiation machine:
(1)
5-50 kV Systems. The leakage air kerma rate measured
at any position five centimeters from the tube housing assembly shall not
exceed one mGy (100 mrad) in any one hour.
(2)
>50 and <500 kV
Systems. The leakage air kerma rate measured at a distance of one
meter from the target in any direction shall not exceed one cGy (one rad) in
any one 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 five centimeters from the surface of the tube housing assembly
shall not exceed 30 cGy (30 rad) per hour.
(3) For each therapeutic radiation machine,
the registrant shall determine, or obtain from the manufacturer, the leakage
radiation existing at the positions specified in 105 CMR 120.436(A)(1) and (2)
for the specified operating conditions. Records on leakage radiation
measurements shall be maintained at the installation for inspection by the
Agency.
(B)
Permanent Beam Limiting Devices. Permanent diaphragms
or cones used for limiting the useful beam shall provide at least the same
degree of attenuation as required for the tube housing assembly.
(C)
Adjustable or Removable Beam
Limiting Devices.
(1) All
adjustable or removable beam limiting devices, diaphragms, cones or blocks
shall not transmit more than 5% of the useful beam for the most penetrating
beam used;
(2) When adjustable beam
limiting devices are used, the position and shape of the radiation field shall
be indicated by a light beam.
(D)
Filter System.
The filter system shall be so designed that:
(1) Filters can not be accidentally displaced
at any possible tube orientation;
(2) For equipment installed after July 9,
1999, an interlock system prevents irradiation if the proper filter is not in
place;
(3) The air kerma rate at a
distance of one meter from the filter shall not exceed one cGy (one rad) per
hour under any operating conditions; and,
(4) Each filter shall be marked as to its
material of construction and its thickness.
(E)
Tube
Immobilization.
(1) The x-ray
tube shall be so mounted that it can not accidentally turn or slide with
respect to the housing aperture; and
(2) The tube housing assembly shall be
capable of being immobilized for stationary portal treatments.
(F)
Source
Marking. The tube housing assembly shall be so marked that it is
possible to determine the location of the source to within five millimeters,
and such marking shall be readily accessible for use during calibration
procedures.
(G)
Beam
Block. Contact therapy tube housing assemblies shall have a
removable shield of material, equivalent in attenuation to 0.5 millimeters of
lead at 100 kV, which can be positioned over the entire useful beam exit port
during periods when the beam is not in use.
(H)
Timer. A
suitable irradiation control device shall be provided to terminate the
irradiation after a pre-set time interval.
(1)
A timer which has a display shall be provided at the treatment control panel.
The timer shall have a pre-set time selector and an elapsed time or time
remaining indicator;
(2) The timer
shall be a cumulative timer which 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 shall
be necessary to reset the elapsed time indicator;
(3) The timer shall terminate irradiation
when a pre-selected time has elapsed, if any dose monitoring system present has
not previously terminated irradiation;
(4) The timer shall permit accurate
pre-setting and determination of exposure times as short as one
second;
(5) The timer shall not
permit an exposure if set at zero;
(6) The timer shall 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,
(7) The timer and back-up
timer if present shall be accurate to within 1% of the selected value or one
second, whichever is greater.
(I)
Control Panel
Functions. The control panel, in addition to the displays required
by other provisions in 105 CMR 120.436, shall have:
(1) An indication of whether electrical power
is available at the control panel and if activation of the x-ray tube is
possible;
(2) An indication of
whether x-rays are being produced;
(3) Means for indicating x-ray tube potential
and current;
(4) The means for
terminating an exposure at any time;
(5) A locking device which will prevent
unauthorized use of the therapeutic radiation machine; and
(6) For therapeutic radiation machines
manufactured after July 9, 1999, a positive display of specific filter(s) in
the beam.
(J)
Multiple Tubes. When a control panel is capable of
energizing more than one x-ray tube:
(1) It
shall only be allowable to activate one X-ray tube at any time;
(2) There shall be an indication at the
control panel identifying which x-ray tube is activated; and
(3) There shall be an indication at the tube
housing assembly when that tube is energized.
(K)
Target-to-skin Distance
(TSD). There shall be a means of determining the central axis TSD
to within one centimeter and of reproducing this measurement to within two
millimeters thereafter.
(L)
Shutters. Unless it is possible to bring the x-ray
output to the prescribed exposure parameters within five seconds after the
x-ray "ON" switch is energized, the beam shall 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 shall be
controlled by the operator from the control panel. An indication of shutter
position shall appear at the control panel.
(M)
Low-filtration X-ray
Tubes. Each therapeutic radiation machine equipped with a
beryllium or other low-filtration window shall be clearly labeled as such upon
the tube housing assembly and shall 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.
(N)
Facility Design Requirements
for Therapeutic Radiation Machines Capable of Operating in the Range 50 kV to
500 kV. In addition to shielding adequate to meet requirements of
105 CMR
120.439, the treatment room shall meet the
following design requirements:
(1)
Aural Communication. Provision shall be made for
continuous two-way aural communication between the patient and the operator at
the control panel;
(2)
Viewing Systems. Provision shall be made to permit
continuous observation of the patient during irradiation and the viewing system
shall be so located that the operator can observe the patient from the control
panel. The therapeutic radiation machine shall not be used for patient
irradiation unless at least one viewing system is operational.
(O)
Additional
Requirements. Treatment rooms which contain a therapeutic
radiation machine capable of operating above 150 kV shall meet the following
additional requirements:
(1) All protective
barriers shall be fixed except for entrance doors or beam
interceptors;
(2) The control panel
shall be located outside the treatment room or inside the treatment room within
a totally enclosed booth with protective barrier walls, door(s), ceiling and
floor;
(3) Interlocks shall be
provided such that all entrance doors, including doors to any interior booths,
shall be closed before treatment can be initiated or continued. If the
radiation beam is interrupted by any 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
(4) When any door referred to in 105 CMR
120.436(O)(3) is opened while the x-ray tube is activated, the air kerma rate
at a distance of one meter from the source shall be reduced to less than 1 mGy
(100 mrad) per hour.
(P)
Full Calibration Measurements.
(1) Full calibration of a therapeutic
radiation machine subject to 105 CMR 120.436 shall be performed by, or under
the direct supervision of, a Qualified Medical Physicist:
(a) Before the first medical use following
installation or reinstallation of the therapeutic radiation machine;
(b) At intervals not exceeding one year;
and
(c) Before medical use under
the following conditions:
1. Whenever quality
assurance check measurements indicate that the radiation output differs by more
than 5% 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.
(d)
Notwithstanding the requirements of 105 CMR 120.436(P)(1)(c):
1. Full calibration of therapeutic radiation
machines with multi-energy capabilities is required only for those modes and/or
energies that are not within their acceptable range; and
2. If the repair, replacement or modification
does not affect all energies, full calibration shall 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
against the criteria in 105 CMR 120.436(P)(1)(c)1.
(2) To satisfy the requirement of
105 CMR 120.436(P)(1), full calibration shall include all measurements
recommended for annual calibration by NCRP Report 69, "Dosimetry of X-ray and
Gamma Ray Beams for Radiation Therapy in the Energy Range 10 keV to 50 MeV"
(1981).
(3) The registrant shall
maintain a record of each calibration for the duration of the registration. The
record shall include the date of the calibration, the manufacturer's name,
model number, and serial number for both the therapeutic radiation machine and
the X-ray tube, the model numbers and serial numbers of the instruments used to
calibrate the therapeutic radiation machine, and the signature of the Qualified
Medical Physicist responsible for performing the calibration.
(Q)
Periodic Quality
Assurance Checks.
(1) Periodic
quality assurance checks shall be performed on therapeutic radiation machines
subject to 105 CMR 120.436, which are capable of operation at greater than or
equal to 50 kV.
(2) To satisfy the
requirement of 105 CMR 120.436(Q)(1), quality assurance checks shall meet the
following requirements:
(a) The registrant
shall perform quality assurance checks in accordance with written procedures
established by the Qualified Medical Physicist; and
(b) The quality assurance check procedures
shall specify the frequency at which tests or measurements are to be performed.
The quality assurance check procedures shall specify that the quality assurance
check shall be performed during the calibration specified in 105 CMR
120.436(P)(1). They shall also state the acceptable tolerance for each
parameter measured in the quality assurance check, when compared to the value
for that parameter determined in the calibration specified in 105 CMR
120.436(P)(1), shall be stated.
(3) The cause for a parameter exceeding a
tolerance set by the Qualified Medical Physicist shall be investigated and
corrected before the system is used for patient irradiation;
(4) Whenever a quality assurance check
indicates a significant change in the operating characteristics of a system, as
specified in the Qualified Medical Physicist's quality assurance check
procedures, the system shall be recalibrated as required in 105 CMR
120.436(P)(1);
(5) The registrant
shall use the dosimetry system described in
105
CMR 120.434(C)(2) to make
the quality assurance check required in 105 CMR 120.436(Q)(2);
(6) The registrant shall have the Qualified
Medical Physicist review and sign the results of each radiation output quality
assurance check within 30 days of the date that the check was
performed;
(7) The registrant shall
ensure that safety quality assurance checks of therapeutic radiation machines
subject to 105 CMR 120.436 are performed at intervals not to exceed 30
days;
(8) Notwithstanding the
requirements of 105 CMR 120.436(Q)(6) and (7), the registrant shall ensure that
no therapeutic radiation machine is used to administer radiation to humans
unless the quality assurance checks required by 105 CMR 120.436(Q)(6) and (7)
have been performed within one month period immediately prior to said
administration;
(9) To satisfy the
requirement of 105 CMR 120.436(Q)(7), safety quality assurance checks shall
ensure proper operation of:
(a) Electrical
interlocks at each external beam radiation therapy room entrance;
(b) Proper operation of the "BEAM-ON" and
termination switches;
(c) Beam
condition indicator lights on the access door(s), control console, and in the
radiation therapy room;
(d) Viewing
systems;
(e) If applicable,
electrically operated treatment room doors activated from inside and outside
the treatment room;
(10)
The registrant shall maintain a record of each quality assurance check required
by 105 CMR 120.436(Q)(1) and (7) for three years. The record shall include the
date of the quality assurance check, the manufacturer's name, model number, and
serial number for the therapeutic radiation machine, the manufacturer's name,
model number and serial number of the instrument(s) used to measure the
radiation output of the therapeutic radiation machine, and the signature of the
individual who performed the periodic quality assurance check.
(R)
Operating
Procedures.
(1) The therapeutic
radiation machine shall not be used for irradiation of patients unless and
until the requirements of 105 CMR 120.436(P) and (Q) have been met;
(2) Therapeutic radiation machines shall not
be left unattended unless secured pursuant to 105 CMR 120.436(I)(5);
(3) Mechanical supporting or restraining
devices shall be used when a patient must be held in position for radiation
therapy;
(4) The tube housing
assembly shall 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 kV. In such cases, the holder shall wear protective
gloves and apron of not less than 0.5 millimeters lead equivalency at 100
kV;
(5) A copy of the current
operating and emergency procedures shall be maintained at the therapeutic
radiation machine control console; and
(6) No individual other than the patient
shall be in the treatment room during exposures from therapeutic radiation
machines operating above 150 kV. At energies less than or equal to 150 kV, any
individual, other than the patient, in the treatment room shall be protected by
a barrier sufficient to meet the requirements of
105 CMR
120.211.
(S)
Possession of Survey
Instrument(s). Each facility location authorized to use a
therapeutic radiation machine in accordance with 105 CMR 120.436 shall possess
appropriately calibrated portable monitoring equipment. As a minimum, such
equipment shall include a portable radiation measurement survey instrument
capable of measuring dose rates over the range ten µSv (one mrem) per
hour to ten mSv (1000 mrem) per hour. The survey instrument(s) shall be
operable and calibrated in accordance with
105 CMR
120.438.
