Minnesota Administrative Rules
Agency 144 - Health Department
Chapter 4731 - RADIATION SAFETY
MEDICAL USE OF RADIOACTIVE MATERIAL
Part 4731.4469 - TELETHERAPY UNITS; FULL CALIBRATION

Universal Citation: MN Rules 4731.4469

Current through Register Vol. 49, No. 13, September 23, 2024

Subpart 1. Calibration required.

A licensee authorized to use a teletherapy unit for medical use must 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:
(1) whenever spot check measurements indicate that the output differs by more than five percent from the output obtained at the last full calibration corrected mathematically for radioactive decay;

(2) following replacement of the source or following reinstallation of the teletherapy unit in a new location; and

(3) 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.

Subp. 2. Required determinations.

To satisfy subpart 1, full calibration measurements must include determination of:

A. the output within plus or minus three 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 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.

Subp. 3. Required system.

A licensee must use the dosimetry system described in part 4731.4468, subpart 1, to measure the output for one set of exposure conditions. The remaining radiation measurements required under subpart 2 may be made using a dosimetry system that indicates relative dose rates.

Subp. 4. Required protocols.

A licensee must make full calibration measurements required under subpart 1 according to published protocols accepted by nationally recognized bodies.

Subp. 5. Required corrections.

A licensee must mathematically correct the outputs determined in subpart 2, item A, for physical decay for intervals not exceeding one month for cobalt-60, six months for cesium-137, or at intervals consistent with one percent decay for all other nuclides.

Subp. 6. Authorized medical physicist.

Full calibration measurements required under subpart 1 and physical decay corrections required under subpart 5 must be performed by the authorized medical physicist.

Subp. 7. Record retention.

A licensee must retain a record of each calibration according to part 4731.4518.

Statutory Authority: MS s 144.1202; 144.1203

Disclaimer: These regulations may not be the most recent version. Minnesota may have more current or accurate information. We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on the state site. Please check official sources.
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.