Nebraska Administrative Code
Topic - HEALTH AND HUMAN SERVICES SYSTEM
Title 180 - CONTROL OF RADIATION
Chapter 7 - MEDICAL USE OF RADIOACTIVE MATERIAL
Section 180-7-075 - FULL CALIBRATION MEASUREMENTS ON GAMMA STEREOTACTIC RADIOSURGERY UNITS

Universal Citation: 180 NE Admin Rules and Regs ch 7 ยง 075

Current through September 17, 2024

075.01 FREQUENCY. A licensee authorized to use a gamma stereotactic radiosurgery unit for medical use must perform full calibration measurements on each unit:

(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 plus or minus 5% from the output obtained at the last full calibration corrected mathematically for radioactive decay;

(ii) Following replacement of the 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 sources or major repair of the components associated with the source assembly; and

(C) At intervals not exceeding one 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.

075.02 DETERMINANTS. To satisfy the requirement of 180 NAC 7-075.01, full calibration measurements must include determination of:

(A) The output within ±3%;

(B) Relative helmet factors to verify that the helmet material provides the required shielding to the patient;

(C) Isocenter coincidence to confirm the centering accuracy of the radiation beam relative to the alignment helmet openings;

(D) Timer accuracy and linearity over the range of use;

(E) On-off error;

(F) Trunnion centricity to determine the rotational center of the source relative to the alignment helmet openings;

(G) Treatment table retraction mechanism, using backup battery power or hydraulic backups with the unit off;

(H) Helmet microswitches to determine if the switches terminate the radiation beam;

(I) Emergency timing circuits; and

(J) Stereotactic frames, localizing devices and trunnions.

075.03 DOSIMETRY SYSTEM. A licensee must use the dosimetry system described in 180 NAC 7-072.01 to measure the output for one set of exposure conditions. The remaining radiation measurements required in paragraph 180 NAC 7-075.02(A) may be made using a dosimetry system that indicates relative dose rates.

075.04 CALIBRATION MEASUREMENT PROTOCOLS. A licensee must make full calibration measurements required by 180 NAC 7-075.01 according to published protocols accepted by nationally recognized bodies.

075.05 MATHEMATICAL CORRECTION OF OUTPUTS. A licensee must mathematically correct the outputs determined in 180 NAC 7-075.02(A) at intervals not exceeding one month for cobalt-60 and at intervals consistent with one percent physical decay for all other radionuclides.

075.06 AUTHORIZED MEDICAL PHYSICIST. Full calibration measurements required by 180 NAC 7-075.01 and physical decay corrections required by 180 NAC 7-075.05 must be performed by the authorized medical physicist.

075.07 RECORDS. A licensee must retain a record of each calibration according to 180 NAC 7-108.

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