10 CFR 35.632, Full Calibration Measurements On Teletherapy Units

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Full calibration measurements on teletherapy units

a

(a) A licensee authorized to use a teletherapy unit for medical use shall perform full calibration measurements on each teletherapy unit--

(1) Before the first medical use of the unit; and
(2) Before medical use under the following conditions:
(i) Whenever spot-check measurements indicate that the output differs by more than 5 percent from the output obtained at the last full calibration corrected mathematically for radioactive decay;
(ii) Following replacement of the source or following reinstallation of the teletherapy unit in a new location;
(iii) Following any repair of the teletherapy unit that includes removal of the source or major repair of the components associated with the source exposure assembly; and
(3) At intervals not exceeding 1 year.

b

(b) To satisfy the requirement of paragraph (a) of this section, full calibration measurements must include determination of--

(1) The output within +/-3 percent for the range of field sizes and for the distance or range of distances used for medical use;
(2) The coincidence of the radiation field and the field indicated by the light beam localizing device;
(3) The uniformity of the radiation field and its dependence on the orientation of the useful beam;
(4) Timer accuracy and linearity over the range of use;
(5) On-off error; and
(6) The accuracy of all distance measuring and localization devices in medical use.

c

(c) A licensee shall use the dosimetry system described in § 35.630(a) to measure the output for one set of exposure conditions. The remaining radiation measurements required in paragraph (b)(1) of this section may be made using a dosimetry system that indicates relative dose rates.

d

(d) A licensee shall make full calibration measurements required by paragraph (a) of this section in accordance with published protocols accepted by nationally recognized bodies.

e

(e) A licensee shall mathematically correct the outputs determined in paragraph (b)(1) of this section for physical decay for intervals not exceeding 1 month for cobalt-60, 6 months for cesium-137, or at intervals consistent with 1 percent decay for all other nuclides.

f

(f) Full calibration measurements required by paragraph (a) of this section and physical decay corrections required by paragraph (e) of this section must be performed by the authorized medical physicist.

g

(g) A licensee shall retain a record of each calibration in accordance with § 35.2632.


External Links

NRC website 10 CFR 35.632