64E-5.641. Full Calibration Measurements on Teletherapy Units

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

(a) Before the first medical use of the unit;

(b) Before medical use 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;

(c) Before medical use following replacement of the source or following reinstallation of the teletherapy unit in a new location;

(d) Before medical use 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

(e) At least every 12 months.

(2) Full calibration measurements shall include the determination of:

(a) The output within 3 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 constancy and linearity over the range of use;

(e) On-off error; and

(f) The accuracy of all distance measuring and localization devices in medical use.

(3) A licensee shall use the dosimetry system described in Rule 64E-5.640, F.A.C., to measure the output for one set of exposure conditions. The remaining radiation measurements required in paragraph 64E-5.6411(2)(a), F.A.C., may be made using a dosimetry system that indicates relative dose rates.

(4) A licensee shall make full calibration measurements required by subsection 64E-5.6411(1), F.A.C., using the manufacturer’s published protocols, published protocols as accepted by nationally recognized bodies or equivalent procedures that have been submitted to the department. An example of a nationally recognized body is the American Association of Physicists in Medicine.

(5) A licensee shall correct mathematically the outputs determined in paragraph 64E-5.6411(2)(a), F.A.C., for physical decay monthly for cobalt 60 and at least every 6 months for cesium 137.

(6) Full calibration measurements required by subsection 64E-5.6411(1), F.A.C., and physical decay corrections required by subsection 64E-5.6411(5), F.A.C., shall be performed by the authorized medical physicist.

(7) A licensee shall maintain a record of each calibration of each teletherapy unit for three years. The record shall include:

(a) The date of the calibration;

(b) The manufacturer’s name, model number, and serial number for both the teletherapy unit and the source;

(c) The model numbers and serial numbers of the instruments used to calibrate the teletherapy unit;

(d) The results and an assessment of the full calibration to include the following:

1. The tables that describe the output of the unit over the range of field sizes and for the range of distances used in radiation therapy;

2. A determination of the coincidence of the radiation field and the field indicated by the light beam localizing device;

3. The measured timer accuracy for a typical treatment time;

4. The calculated on-off error;

5. The estimated accuracy of each distance measuring or localization device; and

6. The signature of the authorized medical physicist.

Rulemaking Authority 404.022, 404.051, 404.061, 404.071, 404.081, 404.141 FS. Law Implemented 404.022, 404.051(1), (4), (5), (6), (8), (9), (10), (11), 404.061(2), (3), 404.071(1), 404.081, 404.141 FS. History–New 8-25-91, Amended 5-12-93, Formerly 10D-91.760, Amended 2-11-10.