Wisconsin Legislature: DHS 157.67(8)(a)4.

(7) Full calibration measurements on teletherapy units.

(a) A licensee authorized to use a teletherapy unit for medical use shall perform full calibration measurements on each teletherapy unit under any of the following circumstances:

1. Before the first medical use of the unit.

2. Before medical use under all of the following conditions:

a. Whenever spot-check measurements indicate that the output differs by more than 5% from the output obtained at the last full calibration corrected mathematically for radioactive decay.

b. Following replacement of the source or following reinstallation of the teletherapy unit in a new location.

c. 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.

3. At intervals not exceeding one year.

(b) To satisfy the requirements of par. (a), full calibration measurements shall include determination of all of the following:

1. The output within plus or minus 3% for the range of field sizes and for the distance or range of distances used for medical use.

2. The coincidence of the radiation field and the field indicated by the light beam localizing device.

3. The uniformity of the radiation field and its dependence on the orientation of the useful beam.

4. Timer accuracy and linearity over the range of use.

5. On-off error.

6. The accuracy of all distance measuring and localization devices in medical use.

(c) A licensee shall use the dosimetry system described in sub. (6) (a) to measure the output for one set of exposure conditions. The remaining radiation measurements required in par. (b) may be made using a dosimetry system that indicates relative dose rates.

(d) A licensee shall perform a full calibration required by par. (a) under published protocols accepted by nationally recognized bodies.

Note: An example of such a nationally recognized body is the American Association of Physicists in Medicine.

(e) A licensee shall mathematically correct the outputs determined in par. (b) 1. for physical decay for intervals not exceeding one month for cobalt-60, 6 months for cesium-137 or at intervals consistent with one percent decay for all other nuclides.

(f) Full calibration measurements required by par. (a) and physical decay corrections required by par. (e) shall be performed by an authorized medical physicist.

(g) A licensee shall retain a record of each calibration under s. DHS 157.71 (21).

(8) Full calibration measurements on remote afterloader units.

(a) A licensee authorized to use a remote afterloader unit for medical use shall perform a full calibration measurement on each unit under any of the following circumstances:

1. Before the first medical use of the unit.

2. Before medical use under all the following conditions:

a. Following replacement of any source or following reinstallation of the unit in a new location outside the facility.

b. Following any repair of the unit that includes removal of the source or major repair of the components associated with the source exposure assembly.

3. Each calendar quarter, at intervals not exceeding 100 days for high dose-rate, medium dose-rate and pulsed dose-rate remote afterloader units with sources whose half-life exceeds 75 days.

4. At intervals not exceeding one year for low dose-rate remote afterloader units.

(b) To satisfy the requirement of par. (a), a full calibration measurement shall include, as applicable, determination of all the following:

1. The output within 5%.

2. Source positioning accuracy to within plus or minus one millimeter.

3. Source retraction with backup battery upon power failure.

4. Length of the source transfer tubes.

5. Timer accuracy and linearity over the typical range of use.

6. Length of the applicators.

7. Function of the source transfer tubes, applicators and transfer tube-applicator interfaces.

(c) In addition to the requirement for full calibration for low dose-rate remote afterloader units in par. (b), a licensee shall perform an autoradiograph of the source to verify inventory and source arrangement at intervals not exceeding one calendar quarter.

(d) A licensee shall use the dosimetry system described in sub. (6) (a) to measure the output.

(e) A licensee shall make a full calibration measurement required by par. (a) under published protocols accepted by nationally recognized bodies.

(f) For low dose-rate remote afterloader units, a licensee may use measurements provided by the source manufacturer that are made under pars. (a) to (e).

(g) A licensee shall mathematically correct the outputs determined in par. (b) 1. for physical decay at intervals consistent with one percent physical decay.

(h) A full calibration measurement required by par. (a) and physical decay correction required by par. (g) shall be performed by the authorized medical physicist.

(i) A licensee shall retain a record of each calibration under s. DHS 157.71 (21).

(j) In addition to the requirements for full calibration for low dose rate remote afterloaders, as specified in par. (b), a licensee shall perform an autoradiograph of the source or sources to verify inventory and source arrangement at intervals not to exceed 3 months.

(9) Full calibration measurements on gamma stereotactic radiosurgery units.

(a) A licensee authorized to use a gamma stereotactic radiosurgery unit for medical use shall perform full calibration measurements on each unit under any of the following circumstances:

1. Before the first medical use of the unit.

2. Before medical use under all of the following conditions:

a. Whenever spot-check measurements indicate that the output differs by more than 5% from the output obtained at the last full calibration corrected mathematically for radioactive decay.

b. Following replacement of the sources or following reinstallation of the gamma stereotactic radiosurgery unit in a new location.

c. 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.

3. 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 the helmet.

(b) To satisfy the requirement of par. (a), a full calibration measurement shall include determination of all the following:

1. The output within plus or minus 3%.

2. Relative helmet factors to verify that the helmet material provides the required shielding to the patient.

3. Isocenter coincidence to confirm the centering accuracy of the radiation beam relative to the helmet openings.

4. Timer accuracy and linearity over the range of use.

5. On-off error.

6. Trunnion centricity to determine the rotational center of the source relative to the helmet openings.

7. Treatment table retraction mechanism, using backup battery power or hydraulic backups with the main power to the unit off.

8. Helmet microswitches to determine if the switches terminate the radiation beam when tripped by unintended movement of the helmet.

9. Emergency timing circuits.

10. Stereotactic frames and localizing devices (trunnions).

(c) A licensee shall use the dosimetry system described in sub. (6) (a) to measure the output for one set of exposure conditions. The remaining radiation measurements required in par. (b) 1. may be made using a dosimetry system that indicates relative dose rates.

(d) A licensee shall make a full calibration measurement required by par. (a) under published protocols accepted by nationally recognized bodies.

Note: An example of such a nationally recognized body is the American Association of Physicists in Medicine.

(e) A licensee shall mathematically correct the outputs determined in par. (b) 1. at intervals not exceeding one month for cobalt-60 and at intervals consistent with one percent physical decay for all other radionuclides.

(f) A full calibration measurement required by par. (a) and physical decay correction required by par. (e) shall be performed by an authorized medical physicist.

(g) A licensee shall retain a record of each calibration under s. DHS 157.71 (21).

(10) Periodic spot-checks for teletherapy units.

(a) A licensee authorized to use teletherapy units for medical use shall perform output spot-checks on each teletherapy unit once in each calendar month that include determination of all of the following:

1. Timer constancy and timer linearity over the range of use.

2. On-off error.

3. The coincidence of the radiation field and the field indicated by the light beam localizing device.

4. The accuracy of all distance measuring and localization devices used for medical use.

5. The output for one typical set of operating conditions measured with the dosimetry system described in sub. (6) (b).

6. The difference between the measurement made in this subd. 5. and the anticipated output expressed as a percentage of the anticipated output, which is the value obtained at last full calibration corrected mathematically for physical decay.

(b) A licensee shall perform measurements required by par. (a) under procedures established by the authorized medical physicist. The authorized medical physicist need not actually perform the spot check measurements.

(c) A licensee shall have the authorized medical physicist review the results of each spot-check within 15 working days. The authorized medical physicist shall notify the licensee in writing of the results of each spot-check within 10 working days.

(d) A licensee authorized to use a teletherapy unit for medical use shall perform safety spot-checks of each teletherapy facility once in each calendar month and after each source installation to assure proper operation of all of the following:

1. Electrical interlocks at each teletherapy room entrance.

2. Electrical or mechanical stops installed to limit use of the primary beam of radiation.

Note: Examples of the limitations in subd. 2. include restriction of source housing angulation or elevation, carriage or stand travel and operation of the beam on-off mechanism.

3. Source exposure indicator lights on the teletherapy unit, on the control console and in the facility.

4. Viewing and intercom systems.

5. Treatment room doors from inside and outside the treatment room.

6. Electrically assisted treatment room doors with the teletherapy unit electrical power turned off.