| (73) Scan--The complete process of collecting x-ray
transmission data for the production of a tomogram. Data can be collected
simultaneously during a single scan for the production of one or more
tomograms.
(74) Scan increment--The amount of relative displacement
of the patient with respect to the CT x-ray system between successive
scans measured along the direction of such displacement.
(75) Scan sequence--A preselected set of 2 or more
scans performed consecutively under preselected CT conditions of operation.
(76) Scan time--The period of time between the beginning
and end of x-ray transmission data accumulation for a single scan.
(77) Scattered radiation--Radiation that has been deviated
in direction during passage through matter.
(78) Secondary dose monitoring system--A system which
will terminate irradiation in the event of failure of the primary
dose monitoring system.
(79) Secondary protective barrier (See definition for
protective barrier).
(80) Shutter--A device attached to the tube housing
assembly which can totally intercept the useful beam and which has
a lead equivalency not less than that of the tube housing assembly.
(81) Source-to-skin distance (SSD)--The distance from
the source to the skin of the patient.
(82) Spot check--Those tests and analyses performed
at specified intervals for the purpose of verifying the consistent
output of radiation equipment.
(83) Stationary beam therapy--Radiation therapy without
displacement of one or more mechanical axes relative to the patient
during irradiation.
(84) Supervision--The delegating of the task of applying
radiation in accordance with this section to persons not licensed
in the healing arts or veterinary medicine, who provide services under
the physician's control. The physician or veterinarian assumes full
responsibility for these tasks and shall assure that the tasks will
be administered correctly.
(85) Target--That part of an x-ray tube or accelerator
onto which a beam of accelerated particles is directed to produce
ionizing radiation or other particles.
(86) Termination of irradiation--The stopping of irradiation
in a fashion which will not permit continuance of irradiation without
the resetting of operating conditions at the control panel.
(87) Therapeutic radiation machine--X ray or electron
producing equipment designed and used for external beam radiation
therapy.
(88) Traceable to a national standard--This indicates
that a quantity or a measurement has been compared to a national standard,
for example, National Institute of Standards and Technology, directly
or indirectly through one or more intermediate steps and that all
comparisons have been documented.
(89) Tube housing assembly--The tube housing with tube
installed. It includes high-voltage and/or filament transformers and
other appropriate elements when such are contained within the tube
housing.
(90) Useful beam--Radiation that passes through the
window, aperture, cone, or other collimating device of the source
housing. Also referred to as the primary beam.
(91) Veterinarian--An individual licensed by the Texas
Board of Veterinary Medical Examiners.
(92) Virtual source--A point from which radiation appears
to originate.
(93) Wedge filter--An added filter effecting continuous
progressive attenuation on all or part of the useful beam.
(94) Written directive--An order in writing for the
administration of radiation to a specific patient as specified in
subsection (h)(1)(F)(ii) of this section.
(f) Accelerators used for research and development
and industrial operations.
(1) Registration. Each person possessing an accelerator
for non-human use, shall apply for and receive a certificate of registration
from the agency before beginning use of the accelerator. A person
may energize the accelerator for purposes of installation and acceptance
testing before receiving a certificate of registration from the agency
in accordance with §289.226(i)(1) of this title.
(2) Facility requirements.
(A) Each accelerator facility shall be provided with
primary and/or secondary barriers as are necessary to assure compliance
with §289.231(m) and (o) of this title.
(B) A radiation survey shall be conducted when the
accelerator is registered and is capable of producing radiation to
determine compliance with §289.231(m) and (o) of this title.
(C) Initial surveys shall be performed as follows.
(i) All new and existing facilities not previously
surveyed shall have a survey made by, or under the direction of, the
registrant.
(ii) A survey report shall be made and shall include,
but not be limited to, the following:
(I) a diagram of the facility that details building
structures and the position of the accelerator, control panel, and
associated equipment;
(II) a description of the accelerator including the
manufacturer, model and serial number, beam type, and beam energy;
(III) a description of the instrumentation used to
determine radiation measurements, including the date and source of
the most recent calibration for each instrument used;
(IV) conditions under which radiation measurements
were taken; and
(V) survey data including:
(-a-) projected annual total effective dose equivalent
(TEDE) in areas adjacent to the accelerator; and
(-b-) a description of workload, use, and occupancy
factors employed in determining the projected annual TEDE.
(iii) The registrant shall maintain a copy of the initial
survey report for inspection by the agency in accordance with subsection
(l) of this section.
(iv) The survey report shall include documentation
of all instances where the facility is in violation of applicable
requirements of this chapter. Any deficiencies detected during the
survey shall be corrected prior to using the accelerator.
(3) Safety requirements.
(A) Interlock systems shall comply with the following
requirements.
(i) Instrumentation, readouts, and controls in the
accelerator console shall be clearly identified.
(ii) Each entrance into a target room or other high
radiation area shall be provided with a safety interlock that shuts
down the machine under conditions of barrier penetration.
(iii) When the production of radiation has been interrupted,
it shall only be possible to resume operation of the accelerator by
manually resetting the console.
(iv) Each safety interlock shall be on an electrical
circuit that allows the interlock to operate independently of all
other safety interlocks.
(v) All safety interlocks shall be designed so that
any defect or component failure in the interlock system prevents operation
of the accelerator.
(vi) A scram button or other emergency power cut-off
switches shall be labeled. The scram button or cut-off switches shall
include a manual reset so that the accelerator cannot be restarted
from the accelerator console without resetting the cut-off switch.
(vii) The safety interlock system shall have a visible
or audible alarm that will indicate when any interlock has been activated.
(viii) All interlocks and visible or audible alarms
shall be tested for proper operation at intervals not to exceed three
months.
(ix) If an interlock or alarm is operating improperly,
it shall be immediately labeled as defective and repaired within 7
calendar days.
(x) Records of tests and repairs required by this paragraph
shall be made and maintained in accordance with subsection (l) of
this section for inspection by the agency.
(B) Each registrant shall develop and implement written
operating and safety procedures. The procedures may be documented
in an electronic reporting system and shall include, but not be limited
to, the following:
(i) methods used to secure the accelerator from unauthorized
use;
(ii) methods of testing and training operators in accordance
with paragraph (4) of this subsection;
(iii) procedures for notifying the proper personnel
in the event of an accident;
(iv) posting requirements;
(v) procedures for testing interlocks, entrance controls,
and alarm systems;
(vi) personnel monitoring;
(vii) maintenance of records; and
Cont'd... |
