A licensee providing mobile remote afterloader service shall—

Check survey instruments before medical use at each address of use or on each day of use, whichever is more frequent; and

Account for all sources before departure from a client's address of use.

In addition to the periodic spot-checks required by § 35.643, a licensee authorized to use mobile afterloaders for medical use shall perform checks on each remote afterloader unit before use at each address of use. At a minimum, checks must be made to verify the operation of—

Electrical interlocks on treatment area access points;

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

Viewing and intercom systems;

Applicators, source transfer tubes, and transfer tube-applicator interfaces;

Radiation monitors used to indicate room exposures;

Source positioning (accuracy); and

Radiation monitors used to indicate whether the source has returned to a safe shielded position.

In addition to the requirements for checks in paragraph (b) of this section, a licensee shall ensure overall proper operation of the remote afterloader unit by conducting a simulated cycle of treatment before use at each address of use.

If the results of the checks required in paragraph (b) of this section 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.

A licensee shall retain a record of each check required by paragraph (b) of this section in accordance with § 35.2647.