Section 2046. Periodic spot-checks

A. Periodic spot-checks for teletherapy units.

1. Licensees 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:

a. Timer accuracy and timer linearity over the range of use;

b. On-off error;

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

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

e. The output for one typical set of operating conditions measured with the dosimetry system described in 12VAC5-481-2044; and

f. The difference between the measurement made in subdivision 1 e of this subsection and the anticipated output, expressed as a percentage of the anticipated output (i.e. the value obtained at last full calibration corrected mathematically for physical decay).

2. Licensees shall perform measurements required by subdivision 1 of this subsection in accordance with written procedures established by the authorized medical physicist (AMP). That individual need not actually perform the spot-check measurements.

3. Licensees shall have the AMP review the results of each spot-check within 15 days. The shall notify the licensee as soon as possible in writing of the results of each spot-check.

4. Licensees 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:

a. Electrical interlocks at each teletherapy room entrance;

b. Electrical or mechanical stops installed for the purpose of limiting use of the primary beam of radiation (restriction of source housing angulation or elevation, carriage or stand travel, and operation of the beam on-off mechanism);

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

d. Viewing and intercom systems;

e. Treatment room doors from inside and outside the treatment room; and

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

5. If the results of the checks required in subdivision 4 of this subsection indicate the malfunction of any system, a licensee shall lock the control console in the off position and not use the unit except as may be necessary to repair, replace, or check the malfunctioning system.

B. Periodic spot-checks for remote afterloader units.

1. Licensees authorized to use a remote afterloader unit for medical use shall perform spot-checks of each remote afterloader facility and on each unit:

a. Before the first use of a high dose-rate, medium dose-rate, or pulsed dose-rate remote afterloader unit on a given day;

b. Before each patient treatment with a low dose-rate remote afterloader unit; and

c. After each source installation.

2. Licensees shall perform the measurements required by subdivision 1 of this subsection in accordance with written procedures established by the AMP. That individual need not actually perform the spot-check measurements.

3. Licensees shall have the authorized medical physicist review the results of each spot-check within 15 days. The AMP shall notify the licensee as soon as possible in writing of the results of each spot-check.

4. To satisfy the requirements of subdivision 1 of this subsection, spot-checks shall, at a minimum, assure proper operation of:

a. Electrical interlocks at each remote afterloader unit room entrance;

b. Source exposure indicator lights on the remote afterloader unit, on the control console, and in the facility;

c. Viewing and intercom systems in each high dose-rate, medium dose-rate, and pulsed dose-rate remote afterloader facility;

d. Emergency response equipment;

e. Radiation monitors used to indicate the source position;

f. Timer accuracy;

g. Clock (date and time) in the unit's computer; and

h. Decayed sources activity in the unit's computer.

5. If the results of the checks required in subdivision 4 of this subsection indicate the malfunction of any system, a licensee shall lock the control console in the off position and not use the unit except as may be necessary to repair, replace, or check the malfunctioning system.

C. Periodic spot-checks for gamma stereotactic radiosurgery units.

1. Licensees authorized to use a gamma stereotactic radiosurgery unit for medical use shall perform spot-checks of each gamma stereotactic radiosurgery facility and on each unit:

a. Monthly;

b. Before the first use of the unit on a given day; and

c. After each source installation.

2. Licensees shall:

a. Perform the measurements required by subdivision 1 of this subsection in accordance with written procedures established by the AMP. That individual need not actually perform the spot-check measurements.

b. Have the AMP review the results of each spot-check within 15 days. The authorized medical physicist shall notify the licensee as soon as possible in writing of the results of each spot-check.

3. To satisfy the requirements of subdivision 1 a of this subsection, spot-checks shall, at a minimum:

a. Assure proper operation of:

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

(2) Helmet microswitches;

(3) Emergency timing circuits; and

(4) Stereotactic frames and localizing devices (trunnions).

b. Determine the following:

(1) The output for one typical set of operating conditions measured with the dosimetry system described in 12VAC5-481-2044;

(2) The difference between the measurement made in subdivision 3 b (1) of this subsection and the anticipated output, expressed as a percentage of the anticipated output (i.e., the value obtained at last full calibration corrected mathematically for physical decay);

(3) Source output against computer calculation;

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

(5) On-off error; and

(6) Trunnion centricity.

4. To satisfy the requirements of subdivisions 1 b and 1 c of this subsection, spot-checks shall assure proper operation of:

a. Electrical interlocks at each gamma stereotactic radiosurgery room entrance;

b. Source exposure indicator lights on the gamma stereotactic radiosurgery unit, on the control console, and in the facility;

c. Viewing and intercom systems;

d. Timer termination;

e. Radiation monitors used to indicate room exposures; and

f. Emergency off buttons.

5. A licensee shall arrange for the repair of any system identified in subdivision 3 of this subsection that is not operating properly as soon as possible.

6. If the results of the checks required in subdivision 4 of this subsection indicate the malfunction of any system, a licensee shall lock the control console in the off position and not use the unit except as may be necessary to repair, replace, or check the malfunctioning system.

Historical Notes

Derived from Volume 32, Issue 24, eff. August 25, 2016.

Statutory Authority

§ 32.1-229 of the Code of Virginia.