Current through September 24, 2024
1.
Leakage Radiation. When the x-ray tube is operated at its maximum rated tube
current for the maximum kV, the leakage kerma rate shall not exceed the value
specified at the distance specified for that classification of therapeutic
radiation machine:
a. 5-50 kV Systems. The
leakage air kerma rate measured at any position 5 centimeters from the tube
housing assembly shall not exceed 100 mrad (1 mGy) in any one hour.
b. >50 and <500 kV Systems. The leakage
air kerma rate measured at a distance of 1 meter from the source in any
direction shall not exceed 1 rad (1 cGy) 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 5 centimeters from the surface
of the tube housing assembly shall not exceed 30 rad (3O cGy) per
hour.
2. 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.
3 Adjustable or Removable Beam-Limiting
Devices.
a. All adjustable or
removable beam-limiting devices, diaphragms, cones or blocks shall not transmit
more than 5 percent of the useful beam for the most penetrating beam
used.
b. When adjustable
beam-limiting devices are used, the position and shape of the radiation field
shall be indicated by a light beam.
4. Filter System. The filter system shall be
so designed that: a. Filters cannot be accidentally displaced at any possible
tube orientation;
b. For equipment installed
after the effective date of these regulations, an interlock system prevents
irradiation if the proper filter is not in place;
c. The air kerma rate escaping from the
filter slot shall not exceed 1 rad (1 cGy) per hour under any operating
conditions; and d. Each filter shall be marked as to its material of
construction and its thickness.
5 Tube Immobilization.
a. The x-ray tube shall be so mounted that it
cannot accidentally turn or slide with respect to the housing aperture; and
b. The tube housing assembly shall
be capable of being immobilized for stationary portal treatments.
6. Source Marking. The
tube housing assembly shall be so marked that it is possible to determine the
location of the source to within 5 millimeters, and such marking shall be
readily accessible for use during calibration procedures.
7. 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.
8. Timer. A suitable irradiation control
device shall be provided to terminate the irradiation after a preset time
interval.
a. A timer which has a display
shall be provided 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 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;
c. The
timer shall terminate irradiation when a preselected time has elapsed, if any
dose monitoring system present has not previously terminated
irradiation;
d. The timer shall
permit accurate presetting and determination of exposure times as short as 1
second;
e. The timer shall not
permit an exposure if set at zero;
f. 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
g. The timer shall be accurate
to within 1 percent of the selected value o r 1 second, whichever is
greater.
9. Control
Panel Functions. The control panel, in addition to the displays required by
other provisions in 1.15.6 shall 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. Means for indicating
x-ray tube potential and current;
d. The means for terminating an exposure at
any time;
e. A locking device which
will prevent unauthorized use of the therapeutic radiation machine; and
f For therapeutic radiation machines manufactured after
the effective date of these regulations, a positive display of specific
filter(s) in the beam.
10. Multiple Tubes. When a control panel may
energize more than one x-ray tube:
a. It
shall be possible to activate only one x-ray tube at any time;
b. There shall be an indication at the
control panel identifying which x-ray tube is activated; and
c. There shall be an indication at the tube
housing assembly when that tube is energized.
11. Source-to-Skin Distance (SSD). There
shall be a means of determining the central axis SSD to within 1 centimeter and
of reproducing this measurement to within 2 millimeters thereafter.
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 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 electrically by the operator from the control panel. An indication
of shutter position shall appear at the control panel.
13. 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.
14 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 1.15.9, the treatment
room shall meet the following design requirements:
a. Aural Communication. Provision shall be
made for continuous two-way aural communication between the patient and the
operator at the control panel.
b.
Viewing Systems. Provision shall be made to permit continuous observation of
the patient during irradiation and 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.
15.
Additional Requirements. Treatment rooms which contain a therapeutic radiation
machine capable of operating above 150 kV shall meet the following additional
requirements:
a. All protective barriers
shall be fixed except for entrance doors or beam interceptors;
b. The control panel shall be located outside
the treatment room or in a totally enclosed booth, which has a ceiling, inside
the room;
c. 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 d. When any door
referred to in 1.15.6(15)(c) is opened while the x-ray tube is activated, the
air kerma rate at a distance of 1 meter from the source shall be reduced to
less than 100 mrad (1 mGy) per hour.
16 Full Calibration Measurements.
a. Full calibration of a therapeutic
radiation machine subject to 1.15.6 shall be performed by, or under the direct
supervision of, a Radiation Therapy Physicist:
i. Before the first medical use following
installation or reinstallation of the therapeutic radiation machine;
ii. At intervals not exceeding 1 year;
and
iii. Before medical use under
the following conditions:
i. Whenever quality
assurance check measurements indic ate that the radiation output differs by
more than 5 percent from the value obtained at the last full calibration and
the difference cannot be easily discerned; and
ii. Following any component replacement,
major repair, or modification of components that could significantly affect the
characteristics of the radiation beam.
b. To satisfy the requirement of
1.15.6(16)(a), 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).
c. A 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 Radiation Therapy Physicist
responsible for performing the calibration.
17 Periodic Quality Assurance Checks.
a. Periodic quality assurance checks shall be
performed on therapeutic radiation machines subject to 1.15.6, which are
capable of operation at greater than 150 kV.
b. To satisfy the requirement of
1.15.6(17)(a), quality assurance checks shall meet the following requirements:
i. The registrant shall perform quality
assurance checks in accordance with written procedures established by the
Radiation Therapy Physicist; and
ii. 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 1.15.6(16)(a). 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 1.15.6(16)(a) shall be stated.
c. The cause for a parameter exceeding a
tolerance set by the Radiation Therapy Physicist shall be investigated and
corrected before the system is used for patient irradiation.
d. Whenever a quality assurance check
indicates a significant change in the operating characteristics of a system, as
specified in the Radiation Therapy Physicist's quality assurance check
procedures, the system shall be recalibrated as required in
1.15.6(16)(a).
e. The registrant
shall use the dosimetry system described in 1.15.4(3) to make the quality
assurance check required in 1.15.6(17)(b).
f. The registrant shall have the Radiation
Therapy Physicist review and sign the results of each radiation output quality
assurance check at intervals not to exceed 1 month. The Radiation Therapy
Physicist shall promptly notify the registrant in writing of the results of
each radiation output quality assurance check. The registrant shall keep a copy
of each written notification for 3 years.
g. Therapeutic radiation machines subject to
1.15.6 shall have safety quality assurance checks of each external beam
radiation therapy facility performed at intervals not to exceed 1
month.
h. To satisfy the
requirement of 1.15.6(17)(g), safety quality assurance checks shall ensure
proper operation of
i. Electrical
interlocks at each external beam radiation therapy room entrance;
ii. Proper operation of the "BEAM-ON" and
termination switches;
iii. Beam
condition indicator lights on the access door(s), control console, and in the
radiation therapy room;
iv. Viewing
systems; and
v. Electrically operated
treatment room doors from inside and outside the treatment room.
i. The registrant shall promptly repair any
system identified in 1.15.6(17)(h) that is not operating properly.
j. The registrant shall maintain a record of
each quality assurance check required by 1.15.6(17)(a) and 1.15.6(17)(g) for 3
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.
18 Operating Procedures.
a. The therapeutic radiation machine shall
not be used for irradiation of patients unless the requirements of 1.15.6(16)
and 1.15.6(17) have been met;
b.
Therapeutic radiation machines shall not be left unattended unless it is
secured pursuant to 1.15.6(9)(e);
c. When a patient must be held in position
for radiation therapy, mechanical supporting or restraining devices shall be
used;
d. 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;
e. A copy of the current operating and
emergency procedures shall be maintained at the therapeutic radiation machine
control console; and
f. 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 1.4.6 of these regulations.
19. Possession of Survey Instrument(s). The
registrant authorized to use a therapeutic radiation machine in accordance with
1.15.6 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 1 mrem (10 nSv) per
hour to 1000 mrem (10 mSv) per hour. The survey instrument(s) shall be operable
and calibrated in accordance with 1.15.8.
Miss. Code Ann.
§
45-14-11
