Current through Register Vol. 30, No. 38, September 20, 2024
A. Equipment requirements.
1. Leakage radiation. When the x-ray tube is
operated at its maximum rated tube current for the maximum kVp, the leakage air
kerma rate shall not exceed the value specified at the distance specified for
that classification of therapeutic radiation machine. For each therapeutic
radiation machine, the registrant shall determine, or obtain from the
manufacturer, the leakage radiation existing at the positions specified:
a. 5-50 kVp Systems. The leakage air kerma
rate measured at any position 5 centimeters from the tube housing assembly
shall not exceed 1 mGy (100 mrad) in any one hour.
b. Greater than 50 kVp and less than 1MeV
Systems. The leakage air kerma rate measured at a distance of 1 meter from the
target in any direction shall not exceed 1 centigray (1 rad) in any 1 hour.
This air kerma rate measurement may be averaged over areas no larger than 100
square centimeters (100 cm2). In addition, the air kerma rate at a distance of
5 centimeters from the surface of the tube housing assembly shall not exceed 30
centigray (30 rad) per hour.
2. Permanent beam limiting devices. A
registrant shall ensure that fixed diaphragms or cones used for limiting the
useful beam provide the same or higher degree of attenuation as required for
the tube housing assembly.
3.
Removable and adjustable beam-limiting devices. A registrant shall ensure that:
a. Removable and adjustable beam-limiting
devices, for the portion of the useful beam to be blocked by these devices,
transmit not more than 1 percent of the original x-ray beam at the maximum
kilovoltage and maximum treatment filter; and
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. A registrant shall ensure that the filter system is designed so that:
a. Filters cannot be accidentally displaced
from the useful beam at any possible tube orientation;
b. For equipment installed after January 1,
2011, 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 centiGray (1 rad) per hour at
one (1) meter under any operating conditions; and
d. Each filter is marked regarding its
material of construction and its thickness or wedge angle for wedge
filters.
5. X-ray tube
immobilization. A registrant shall ensure that the tube housing assembly is
capable of being immobilized during stationary treatments and the x-ray tube
shall be so mounted that it cannot accidentally turn or slide with respect to
the housing aperture.
6. Focal spot
marking. A registrant shall ensure that the tube housing assembly is marked so
that it is possible to determine the location of the focal spot to within 5
millimeters, and the marking is readily accessible for use during calibration
procedures.
7. Therapy treatment
timers. A registrant shall:
a. Provide a timer
that has a display at the treatment control panel. The timer shall have a
preset time selector and an elapsed time indicator;
b. Ensure that the timer is a cumulative
timer that activates with the radiation, retains its reading after irradiation
is interrupted or terminated, and requires the operator to reset the preset
time selector after irradiation is terminated and before irradiation can be
reinitiated;
c. Ensure that the
timer terminates irradiation when a preselected time has elapsed;
d. Ensure that the timer permits accurate
presetting and determination of exposure times as short as one
second;
e. Ensure that the timer
does not permit an exposure if set at zero; and
f. Ensure that the timer does not activate
until the shutter is opened if irradiation is controlled by a shutter
mechanism.
8. Control
panel functions. In addition to the displays required in other provisions of
this Section, a registrant shall ensure that a control panel has:
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 kVp and x-ray tube
current;
d. A means for terminating
an exposure at any time;
e. A
locking device that will prevent unauthorized use of the x-ray system;
and
f. For x-ray equipment
installed after January 2, 1996, a positive display of specific filters in the
beam.
9. Multiple tubes.
If one control panel is used to energize more than one x-ray tube a registrant
shall ensure that:
a. It is possible to
activate only one x-ray tube during any time interval,
b. There is an indication at the control
panel that identifies which x-ray tube is energized, and
c. There is an indication at the tube housing
assembly when that tube is energized.
10. Source-to-patient distance. A registrant
shall ensure that there is a means of determining the source-to-patient
distance to within 1 centimeter.
11. Shutters. Unless it is possible to bring
the x-ray output to the prescribed exposure parameters within five seconds, a
registrant shall ensure that the entire useful beam is automatically attenuated
by a shutter with a lead equivalency not less than that of the tube housing
assembly. In addition the registrant shall ensure that:
a. After the unit is at operating parameters,
the operator controls the shutter electrically from the control panel;
and
b. An indication of shutter
position appears at the control panel.
12. Low filtration x-ray tubes. A registrant
shall ensure that each x-ray system equipped with a beryllium or other
low-filtration window is clearly labeled as low-filtration equipment on the
tube housing assembly and at the control panel.
B. Facility design requirements. In addition
to shielding necessary to meet the requirements of Article 4 of this Chapter, a
registrant shall ensure that:
1. Warning
lights. A treatment room to which access is possible through more than one
entrance has a warning light, in a readily observable position near the outside
of any access doors, which will indicate when the useful beam is
"on."
2. Voice communication.
Two-way oral communication is possible between the patient and the operator at
the control panel; or where excessive noise levels make oral communication
impractical, another effective method of communication.
3. Viewing systems. Windows, mirrors,
closed-circuit television, or an equivalent system, permits continuous
observation of the patient during irradiation and is located so that the
operator can observe the patient from the control panel. If the primary viewing
system is by electronic means (for example, television), the registrant shall
have an alternate viewing system for use in the event of electronic
failure.
4. Systems above 150 kVp.
For treatment rooms that contain an x-ray system capable of operating above 150
kVp a registrant shall ensure that:
a. All
necessary shielding, except for any beam interceptor, is provided by fixed
barriers;
b. The control panel is
within a protective booth equipped with an interlocked door, or located outside
the treatment rooms;
c. All doors
of the treatment room are electrically connected to the control panel so that
x-ray production cannot occur unless all doors are closed; and
d. Opening of any door to the treatment room
during exposure results in automatic termination of x-ray production or
reduction of radiation levels to an average of no more than 516 nC/kg (2
milliroentgens) per hour and a maximum of 2.6 µC/kg (10 milliroentgens) per
hour at a distance of 1 meter (3.3 feet) from the target in any direction, and
restoration of the machine to full operation is possible only from the control
panel after the termination or reduction.
C. Surveys. A registrant shall ensure that:
1. All facilities, both new and existing, or
not previously surveyed, are surveyed before being put into service for the
treatment of patients by, or under the direction of, a person trained and
experienced in the principles of radiation protection, and perform additional
surveys of a facility after any change in the facility or a facility's
equipment that might cause a significant increase in radiation hazard, before
being put into service for the treatment of patients.
2. The person conducting the survey reports
the survey findings in writing to the individual in charge of the facility and
maintains a copy of the survey report for inspection by the
Department.
3. The installation is
operated in compliance with any limitations indicated by the protection survey
required by subsection (C)(1).
D. Calibrations. A registrant shall ensure
that:
1. The calibration of a therapeutic
x-ray system includes, but is not limited to, the following determinations:
a. Verification that the x-ray system is
operating in compliance with the design specifications;
b. The dose rate equivalent for each
combination of field size, technique factors, filter, and treatment distance
used;
c. The degree of congruence
between the radiation field and the field indicated by the localizing device if
a localizing device is used; and
d.
An evaluation of the uniformity of the radiation field symmetry for the field
sizes used and any dependence upon source housing assembly
orientation;
2. The
calibration of an x-ray system is performed at intervals not to exceed annually
and after any change or replacement of components that could cause a change in
the radiation output;
3. The
calibration of the radiation output of the x-ray system is performed by, or
under the direction of, a person trained and experienced in performing
calibrations, who is physically present at the facility during
calibration;
4. Calibration of the
radiation output of an x-ray system is performed with a calibrated instrument.
The registrant shall ensure that calibration of the instrument is directly
traceable to the National Institute of Standards and Technology (NIST) and that
the instrument has been calibrated within the preceding 24 months;
5. Records of calibration performed under
subsection (D)(3) are maintained for at least three years after completion of
the calibration and are made available for inspection by the Department;
and
6. A copy of the most recent
calibration is available for use by the operator at the control
panel.
E. Spot checks. A
registrant shall ensure that spot checks are performed on therapeutic x-ray
systems capable of operation at greater than 150 kVp. The registrant shall
ensure that spot checks meet the following requirements:
1. The spot-check procedures are in writing
and have been developed by a qualified expert;
2. The measurements taken during the spot
checks demonstrate the degree of consistency of the operating characteristics
that can affect the radiation output of the x-ray system;
3. The written spot-check procedure specifies
the frequency of the tests or measurements, made at intervals not to exceed
monthly;
4. The spot-check
procedure identifies conditions that require recalibration of the system in
accordance with subsection (D)(l); and
5. Records of spot-check measurements
performed as required by subsection (E)(3) are maintained, available for
inspection by the Department, for three years following the
measurements.
F.
Operating procedures. A registrant shall ensure that:
1. Therapeutic x-ray systems are not left
unattended unless the system is secured according to subsection
(A)(8)(e);
2. If a patient must be
held in position for radiation therapy, mechanical supporting or restraining
devices are used;
3. The tube
housing assembly is not held by an individual during exposures; and
4. At 150 kVp or more the patient is the only
person in the treatment room during production of radiation. At less than 150
kVp an individual may be in the room with patient, provided the individual is
protected by a barrier sufficient to meet the requirements of Article 4 of this
Chapter.
G. Electronic
Brachytherapy units are exempt from the requirements of this Section.