64E-5.6412. Full Calibration Measurements on Gamma Stereotactic Radiosurgery Units

(1) A licensee authorized to use a gamma stereotactic radiosurgery unit for medical use shall perform full calibration measurements on each gamma stereotactic radiosurgery: (a) Before the first medical use of the unit; (b)1. 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; 2. Before medical use following replacement of the source or following reinstallation of the gamma stereotactic radiosurgery unit in a new location; 3. Following any repair of the gamma stereotactic radiosurgery unit that includes removal of the sources or major repair of the components associated with the source assembly; and (c) At intervals not exceeding 1 year, with the exception 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 of the gamma stereotactic radiosurgery unit shall include the determination of: (a) The output within 3 percent; (b) Relative helmet factors; (c) Isocenter coincidence; (d) Timer constancy and linearity over the range of use; (e) On-off errors; (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 (trunnions). (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-5.6412(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-5.6412(1), F.A.C., in accordance with published protocols accepted by nationally recognized bodies. (5) A licensee shall correct mathematically the outputs determined in paragraph 64E-5.6412(2)(a), F.A.C., at intervals not exceeding 1 month for cobalt-60 and at intervals consistent with 1 percent physical decay for all other radionuclides. (6) Full calibration measurements required by subsection 64E-5.6412(1), F.A.C., and physical decay corrections required by subsection 64E-5.6412(5), F.A.C., shall be performed by the authorized medical physicist. (7) A licensee shall maintain a record of each gamma stereotactic radiosurgery unit calibration 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 gamma stereotactic radiosurgery unit and the source; (c) The model numbers and serial numbers of the instruments used to calibrate the gamma stereotactic radiosurgery unit; (d) The results and an assessment of the full calibrations; and (e) The signature of the authorized medical physicist.