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.