Section 35.647 - Additional technical requirements for mobile remote afterloader units(a) A licensee providing mobile remote afterloader service shall-(1) Check survey instruments before medical use at each address of use or on each day of use, whichever is more frequent; and(2) Account for all sources before departure from a client's address of use.(b) 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-(1) Electrical interlocks on treatment area access points;(2) Source exposure indicator lights on the remote afterloader unit, on the control console, and in the facility;(3) Viewing and intercom systems;(4) Applicators, source transfer tubes, and transfer tube-applicator interfaces;(5) Radiation monitors used to indicate room exposures;(6) Source positioning (accuracy); and(7) Radiation monitors used to indicate whether the source has returned to a safe shielded position.(c) 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.(d) 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.(e) A licensee shall retain a record of each check required by paragraph (b) of this section in accordance with § 35.2647 .