| This notification serves to draw your attention to a recent incident that occurred in a private hospital in which a non-radiation worker of the hospital was inadvertently exposed to radiation in a medical linear accelerator (linac) room.
The incident took place during a quality assurance (QA) session for a 6 MV linac conducted by the physicists of the hospital. The session was somehow interrupted by an unrelated initiating event that eventually led to the scenario where the medical linac was turned on by the QA team who was unaware that a ward assistant was present in the linac room, until the end of the exposure which lasted about 30 seconds and delivered about 154 monitoring units (MU).
Initial post-incident assessment indicated that the dose to the ward assistant might be about 0.1 mSv, due to scattered radiation from a 10 cm by 10 cm beam directed downwards to the QA phantom and some leakage radiation from the linac treatment head.
The Board takes very seriously any incidents that result in unplanned radiation exposure, whether to patients or workers. We would therefore like to remind you, as a licensee licensed for the possession and use of radiotherapy facilities, to exercise due diligence to prevent similar incidents. Please review the current procedures in your Radiotherapy Department, and make sure that a ‘last man out’ procedure, or equivalent ones serving the same purposes, is set up and practiced by all relevant staff. Effective measures should always be instituted to prevent any persons from being exposed to unplanned radiation exposure in medical irradiation facilities, including linacs, afterloading and other brachytherapy installations.
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