Louisiana Administrative Code
Title 33 - ENVIRONMENTAL QUALITY
Part XV - Radiation Protection
Chapter 7 - Use of Radionuclides in the Healing Arts
Section XV-756 - Full Calibration Measurements on Teletherapy Units, Remote Afterloader Units, and Gamma Stereotactic Radiosurgery Units

Universal Citation: LA Admin Code XV-756

Current through Register Vol. 50, No. 9, September 20, 2024

A. 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 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; and

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

c. at intervals not exceeding one year.

2. To satisfy the requirement of Paragraph A.1 of this Section, full calibration measurements shall include 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 accuracy, constancy, and linearity;

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 LAC 33:XV.755 to measure the output for one set of exposure conditions. The remaining radiation measurements required in Subparagraph A.2.a of this Section may then be made using a dosimetry system that indicates relative dose rates.

4. A licensee shall make full calibration measurements required by Paragraph A.1 of this Section in accordance with the procedures recommended by Task Group 21 of the Radiation Therapy Committee of the American Association of Physicists in Medicine that are described in Medical Physics, vol. 10, number 6, 1983, pp. 741-771, and vol. 11, number 2, 1984, p. 213.

5. A licensee shall correct mathematically the outputs determined in Subparagraph A.2.a of this Section for physical decay for intervals not exceeding one month for cobalt-60 and intervals not exceeding six months for cesium-137.

6. Full calibration measurements required by Paragraph A.1 of this Section and physical decay corrections required by Paragraph A.5 of this Section shall be performed by a teletherapy physicist named on the licensee's license or authorized by a license issued by the U.S. Nuclear Regulatory Commission or an agreement state to perform such services.

7. A licensee shall retain a record of each calibration in accordance with Subsection D of this Section.

B. Full Calibration Measurements on Remote Afterloader Units

1. A licensee authorized to use a remote afterloader unit for medical use shall 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. following replacement of the source or following reinstallation of the unit in a new location outside the facility; and

ii. following any repair of the unit that includes removal of the source or major repair of the components associated with the source exposure assembly;

c. at intervals not exceeding one quarter for high dose-rate, medium dose-rate, and pulsed dose-rate remote afterloader units with sources whose half-life exceeds 75 days; and

d. at intervals not exceeding one year for low dose-rate remote afterloader units.

2. To satisfy the requirement of Paragraph B.1 of this Section, full calibration measurements shall include, as applicable, determination of:
a. the output within 5 percent;

b. source positioning accuracy to within 1 millimeter;

c. source retraction with backup battery upon power failure;

d. length of the source transfer tubes;

e. timer accuracy and linearity over the typical range of use;

f. length of the applicators; and

g. function of the source transfer tubes, applicators, and transfer tube-applicator interfaces.

3. A licensee shall use the dosimetry system described in LAC 33:XV.755.A to measure the output.

4. A licensee shall make the full calibration measurements required by this Subsection in accordance with published protocols accepted by nationally-recognized bodies.

5. In addition to the requirements for full calibrations for low dose-rate remote afterloader units in Paragraph B.2 of this Section, a licensee shall perform an autoradiograph of the sources to verify inventory and source arrangement at intervals not exceeding one quarter.

6. For low dose-rate remote afterloader units, a licensee may use measurements provided by the source manufacturer that are made in accordance with Paragraphs B.1-5 of this Section.

7. A licensee shall mathematically correct the output determined in Subparagraph B.2.a of this Section for physical decay at intervals consistent with 1 percent physical decay.

8. Full calibration measurements required by Paragraph B.1 of this Section and physical decay corrections required by Paragraph B.7 of this Section shall be performed by the authorized medical physicist.

9. A licensee shall retain a record of each calibration in accordance with Subsection D of this Section.

C. 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 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 more than 5 percent 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.

2. To satisfy the requirement of Paragraph C.1 of this Section, full calibration measurements shall include determination of:
a. the output within 3 percent;

b. relative helmet factors;

c. isocenter coincidence;

d. timer accuracy and linearity over the range of use;

e. "on-off" error;

f. trunnion centricity;

g. proper functioning of treatment table retraction mechanism, using backup battery power or hydraulic backups with the unit off;

h. proper functioning of helmet microswitches;

i. proper functioning of emergency timing circuits; and

j. proper functioning of stereotactic frames and localizing devices (trunnions).

3. A licensee shall use the dosimetry system described in LAC 33:XV.755.A to measure the output for one set of exposure conditions. The remaining radiation measurements required in Subparagraph C.2.a of this Section may be made using a dosimetry system that indicates relative dose rates.

4. A licensee shall make the full calibration measurements required by Paragraph C.1 of this Section in accordance with published protocols accepted by nationally-recognized bodies.

5. A licensee shall mathematically correct the outputs determined in Subparagraph C.2.a of this Section at intervals not exceeding one month for cobalt-60 and at intervals consistent with 1 percent physical decay for all other radionuclides.

6. Full calibration measurements required by Paragraph C.1 of this Section and physical decay corrections required by Paragraph C.5 of this Section shall be performed by the authorized medical physicist.

7. A licensee shall retain a record of each calibration in accordance with Subsection D of this Section.

D. Records of Teletherapy Unit, Remote Afterloader Unit, and Gamma Stereotactic Radiosurgery Unit Full Calibrations. A licensee shall maintain a record of the teletherapy unit, remote afterloader unit, and gamma stereotactic radiosurgery unit full calibrations required by Subsections A, B, and C of this Section for three years. The record shall include:

1. the date of the calibration;

2. the manufacturer's name, model number, and serial number of the teletherapy, remote afterloader, or gamma stereotactic radiosurgery unit, the source, and the instruments used to calibrate the unit;

3. the results and an assessment of the full calibrations;

4. the results of the autoradiograph required for low dose-rate remote afterloader units; and

5. the signature of the authorized medical physicist who performed the full calibration.

AUTHORITY NOTE: Promulgated in accordance with R.S. 30:2001 et seq.

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