| (I) Irradiation shall not be possible until a selection
of energy has been made at the treatment console.
(II) An interlock system shall be provided to prevent
irradiation if any selected operations carried out in the treatment
room do not agree with the selected operations carried out at the
treatment console.
(III) The nominal energy value selected shall be displayed
at the treatment console before and during irradiation.
(xiv) Equipment capable of both stationary beam therapy
and moving beam therapy shall meet the following requirements.
(I) Irradiation shall not be possible until a selection
of stationary beam therapy or moving beam therapy has been made at
the treatment console.
(II) An interlock system shall be provided to prevent
irradiation if any selected operations carried out in the treatment
room do not agree with the selected operations carried out at the
treatment console.
(III) The selection of stationary or moving beam shall
be displayed at the treatment console. An interlock system shall be
provided to ensure that the equipment can only operate in the mode
that has been selected.
(IV) For equipment manufactured after March 1, 1989,
an interlock system shall be provided to terminate irradiation if
movement of the gantry occurs during stationary beam therapy or stops
during moving beam therapy unless such stoppage is a preplanned function.
(V) Moving beam therapy shall be controlled to obtain
the selected relationships between incremental dose monitor units
and incremental angle of movement.
(-a-) For equipment manufactured after March 1, 1989,
an interlock system shall be provided to terminate irradiation if
the number of dose monitor units delivered in any 10 degrees of arc
differs by more than 20% from the selected value.
(-b-) For equipment manufactured after March 1, 1989,
where gantry angle terminates the irradiation in arc therapy, the
dose monitor units shall differ by less than 5.0% from the value calculated
from the absorbed dose per unit angle relationship.
(VI) Where the dose monitor system terminates the irradiation
in moving beam therapy, the termination of irradiation shall be as
required by clause (vii) of this subparagraph.
(xv) For equipment manufactured after March 1, 1989,
a system shall be provided from whose readings the absorbed dose rate
at a reference point in the treatment volume can be calculated. The
radiation detectors specified in subparagraph (iv) of this paragraph
may form part of this system. In addition, the dose monitor unit rate
shall be displayed at the treatment console. If the equipment can
deliver under any conditions an absorbed dose rate at the normal treatment
distance more than twice the maximum value specified by the manufacturer
for any machine parameters utilized, a device shall be provided that
terminates irradiation when the absorbed dose rate exceeds a value
twice the specified maximum. The dose rate at which the irradiation
will be terminated shall be in a record maintained by the registrant
in accordance with subsection (l) of this section for agency inspection.
(xvi) The registrant shall determine, or obtain from
the manufacturer, the location with reference to an accessible point
on the radiation head of the x-ray target or the virtual source of
x-rays and the electron window or the virtual source of electrons
if the system has electron beam capabilities.
(xvii) Capabilities shall be provided so that all radiation
safety interlocks can be checked for correct operation.
(B) Facility and shielding requirements.
(i) Each installation shall be provided with primary
and/or secondary barriers as are necessary to assure compliance with
§289.231(m) and (o) of this title.
(ii) All protective barriers shall be fixed except
for entrance doors or beam interceptors.
(iii) The console shall be located outside the treatment
room and all emergency buttons/switches shall be clearly labeled as
to their functions.
(iv) Windows, mirrors, closed-circuit television, or
an equivalent system shall be provided to permit continuous observation
of the patient following positioning and during irradiation and shall
be so located that the operator may observe the patient from the console.
(I) Should the viewing system described in clause (iv)
of this subparagraph fail or be inoperative, treatment shall not be
performed with the unit until the system is restored.
(II) In a facility that has a primary viewing system
by electronic means and an alternate viewing system, should both viewing
systems described in clause (iv) of this subparagraph fail or be inoperative,
treatment shall not be performed with the unit until one of the systems
is restored.
(v) Provision shall be made for continuous two-way
aural communication between the patient and the operator at the console
independent of the accelerator. However, where excessive noise levels
or treatment requirements make aural communication impractical, other
methods of communication shall be used. When this is the case, a description
of the alternate method shall be submitted to and approved by the
agency.
(vi) Treatment room entrances shall be provided with
a warning light in a readily observable position near the outside
of all access doors to indicate when the useful beam is "on."
(vii) Interlocks shall be provided such that all entrance
doors 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 console.
(C) Surveys, calibrations, spot checks, and operational
requirements.
(i) Surveys shall be performed as follows.
(I) All new and existing facilities not previously
surveyed shall have an initial survey made by a licensed medical physicist
with a specialty in therapeutic radiological physics, who shall provide
a written report of the survey to the registrant. The physicist who
performs the survey shall be a person who did not consult in the design
of the therapeutic radiation machine installation and is not employed
by or within any corporation or partnership with the person who consulted
in the design of the installation. In addition, such surveys shall
be done after any change in the facility or equipment that might cause
a significant increase in radiation hazard.
(II) The survey report shall include, but not be limited
to the following:
(-a-) a diagram of the facility that details building
structures and the position of the console, therapeutic radiation
machine, and associated equipment;
(-b-) a description of the therapeutic radiation system,
including the manufacturer, model and serial number, beam type, and
beam energy;
(-c-) a description of the instrumentation used to
determine radiation measurements, including the date and source of
the most recent calibration for each instrument used;
(-d-) conditions under which radiation measurements
were taken; and
(-e-) survey data including:
(-1-) projected annual TEDE in areas adjacent to the
therapy room; and
(-2-) a description of workload, use, and occupancy
factors employed in determining the projected annual TEDE.
(III) The registrant shall maintain a copy of the survey
report and a copy of the survey report shall be provided to the agency
within 30 days of completion of the survey. Records of the survey
report shall be maintained in accordance with subsection (l) of this
section for inspection by the agency.
(IV) The survey report shall include documentation
of all instances where the installation is in violation of applicable
regulations. Any deficiencies detected during the survey shall be
corrected prior to using the machine.
(ii) Calibrations of therapeutic systems shall be performed
as follows.
(I) The calibration of systems subject to this subsection
shall be performed in accordance with an established calibration protocol
before the system is first used for irradiation of a patient and thereafter
at time intervals that do not exceed 12 months and after any change
that might significantly alter the calibration, spatial distribution,
or other characteristics of the therapy beam. The calibration procedures
shall be in writing, or documented in an electronic reporting system,
and shall have been developed by a licensed medical physicist with
a specialty in therapeutic radiological physics. The calibration protocol
entitled, "Protocol for Clinical Reference Dosimetry of High-Energy
Photon and Electron Beams," Task Group 51, Radiation Therapy Committee,
American Association of Physicists in Medicine, Medical Physics 26(9):
1847 - 1870, September 1999, would be accepted as an established protocol.
At a minimum, the calibration protocol shall include items in subclauses
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