Texas Register, Volume 32, Number 23, Pages 3077-3422, June 8, 2007 Page: 3,161
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(E) results of the autoradiograph required for low dose-
rate remote afterloader unit.
(111) Full calibration measurements on gamma stereotactic ra-
diosurgery units.
(1) A licensee authorized to use a gamma stereotactic ra-
diosurgery unit for medical use shall perform full calibration measure-
ments on each gamma stereotactic radiosurgery unit as follows:
(A) before the first medical use of the unit;
(B) before medical use under the following conditions:
(i) whenever spot check measurements indicate that
the output differs by more than 5.0% from the output obtained at the
last full calibration corrected mathematically for radioactive decay;
(ii) following replacement of the sealed sources or
following reinstallation of the gamma stereotactic radiosurgery unit in
a new location; and
(iii) following any repair of the gamma stereotactic
radiosurgery unit that includes removal of the sealed sources or major
repair of the components associated with the sealed source exposure
assembly; and
(C) at intervals not to exceed one year, with the excep-
tion that relative helmet factors need only be determined before the first
medical use of a helmet and following any damage to a helmet.
(2) Full calibration measurements shall include determina-
tion of the following:
(A) the output within plus or minus 3.0%;
(B) relative helmet factors;
(C) isocenter coincidence;
(D) timer accuracy and linearity over the range of use;
(E) "on-off" error;
(F) trunnion centricity;
(G) treatment table retraction mechanism, using backup
battery power or hydraulic backups with the unit "off";
(H) helmet microswitches;
(I) emergency timing circuits; and
(J) stereotactic frames and localizing devices (trun-
nions).
(3) The licensee shall use the dosimetry system described
in subsection (iii)(1) of this section to measure the output for one set of
exposure conditions. The remaining radiation measurements required
in paragraph (2)(A) of this subsection may be made using a dosimetry
system that indicates relative dose rates.
(4) The licensee shall make full calibration measurements
required by paragraph (1) of this subsection in accordance with pub-
lished protocols accepted by nationally recognized bodies.
(5) The licensee shall mathematically correct the outputs
determined in paragraph (2)(A) of this subsection at intervals not to
exceed one month for cobalt-60 and at intervals consistent with 1.0%
physical decay for all other radionuclides.
(6) Full calibration measurements required by paragraph
(1) of this subsection and physical decay corrections required by para-
graph (5) of this subsection shall be performed by an authorized med-
ical physicist.(7) The licensee shall retain a record of each calibration in
accordance with subsection (www) of this section for inspection by the
agency. The record shall include the following:
(A) date of the calibration;
(B) manufacturer's name, model number, and serial
number for the unit and the unit's sealed source and the instruments
used to calibrate the unit;
(C) results and an assessment of the full calibration; and
(D) signature of the authorized medical physicist who
performed the full calibration.
(mmm) Periodic spot checks for teletherapy units.
(1) A licensee authorized to use teletherapy units for med-
ical use shall perform output spot checks on each teletherapy unit once
in each calendar month that include determination of the following:
(A) timer constancy and linearity over the range of use;
(B) "on-off" error;
(C) the coincidence of the radiation field and the field
indicated by the light beam localizing device;
(D) the accuracy of all distance measuring and localiza-
tion devices used for medical use;
(E) the output for one typical set of operating conditions
measured with the dosimetry system described in subsection (iii)(2) of
this section; and
(F) the difference between the measurement made
in paragraph (1)(E) of this subsection and the anticipated output,
expressed as a percentage of the anticipated output, the value obtained
at last full calibration corrected mathematically for physical decay.
(2) The licensee shall perform measurements required by
paragraph (1) of this subsection in accordance with written procedures
established by an authorized medical physicist. That authorized med-
ical physicist need not actually perform the spot check measurements.
The licensee shall maintain a copy of the written procedures in ac-
cordance with subsection (www) of this section for inspection by the
agency.
(3) The licensee authorized to use a teletherapy unit for
medical use shall perform safety spot checks of each teletherapy fa-
cility once in each calendar month and after each sealed source instal-
lation to assure proper operation of the following:
(A) electrical interlocks at each teletherapy room en-
trance;
(B) electrical or mechanical stops installed for the pur-
pose of limiting use of the primary beam of radiation (restriction of
sealed source housing angulation or elevation, carriage or stand travel
and operation of the beam "on-off" mechanism);
(C) sealed source exposure indicator lights on the
teletherapy unit, on the control console, and in the facility;
(D) viewing and intercom systems;
(E) treatment room doors from inside and outside the
treatment room; and
(F) electrically assisted treatment room doors with the
teletherapy unit electrical power turned "off".
(4) The licensee shall have an authorized medical physicist
review the results of each spot check and submit a written report to the
licensee within 15 days of the spot check.PROPOSED RULES June 8, 2007 32 TexReg 3161
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Texas. Secretary of State. Texas Register, Volume 32, Number 23, Pages 3077-3422, June 8, 2007, periodical, June 8, 2007; Austin, Texas. (https://texashistory.unt.edu/ark:/67531/metapth97400/m1/84/?rotate=90: accessed July 16, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu; crediting UNT Libraries Government Documents Department.