Or. Admin. R. 333-116-0570 - Full Calibration Measurement
(1) A licensee authorized to use a
teletherapy unit for medical use must perform full calibration measurements on
each teletherapy unit:
(a) Before the first
medical use of the unit; and
(b)
Before medical use under the following conditions:
(A) Whenever spot-check measurements indicate
that the output differs by more than five percent from the output obtained at
the last full calibration corrected mathematically for radioactive
decay;
(B) Following replacement of
the radioactive source or following reinstallation of the teletherapy unit in a
new location;
(C) Following any
repair of the teletherapy unit that includes removal of the radioactive source
or major repair of the components associated with the source exposure assembly;
and
(c) At intervals not
exceeding one year.
(2)
To satisfy the requirement of section (1) of this rule, full calibration
measurements must include determination of:
(a) The output within three percent for the
range of field sizes and for the distance or range of distances used for
medical use;
(b) The coincidence of
the radiation field and the field indicated by the light beam localizing
device;
(c) The uniformity of the
radiation field and its dependence on the orientation of the useful
beam;
(d) Timer accuracy,
constancy, and linearity;
(e)
On-off error; and
(f) The accuracy
of all distance measuring and localization devices in medical
use.
(3) A licensee must
use the dosimetry system described in OAR 333-116-0560(1) to measure the output
for one set of exposure conditions. The remaining radiation measurements
required in subsection (2)(a) of this rule may then be made using a dosimetry
system that indicates relative dose rates.
(4) A licensee must make full calibration
measurements required by section (1) of this rule in accordance with published
protocols accepted by nationally recognized bodies.
(5) A licensee must correct mathematically
the outputs determined in subsection (2)(a) of this rule for physical decay for
intervals not exceeding one month for cobalt-60 and intervals not exceeding six
months for cesium-137, or at intervals consistent with one percent decay for
all other nuclides.
(6) Full
calibration measurements required by section (1) of this rule and physical
decay corrections required by section (5) of this rule must be performed by a
teletherapy or medical physicist certified to perform such measurements and
named on the licensee's license or authorized by a license issued by the
Nuclear Regulatory Commission or an Agreement State to perform such
services.
(7) A licensee must
retain a record of each calibration in accordance with OAR 333-100-0057. The
record must include the date of the calibration, the manufacturer's name, model
number, and serial number for both the teletherapy unit and the source, the
model numbers and serial numbers of the instruments used to calibrate the
teletherapy unit, tables that describe the output of the unit over the range of
field sizes and for the range of distances used in radiation therapy, a
determination of the coincidence of the radiation field and the field indicated
by the light beam localizing device, the measured timer accuracy for a typical
treatment time, the calculated on-off error, the estimated accuracy of each
distance measuring or localization device and the signature of the teletherapy
physicist.
Notes
Statutory/Other Authority: ORS 453.635
Statutes/Other Implemented: ORS 453.605 - 453.807
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