Posted on: 07 June 2012
Update 6/4/12: The licensee determined that the radiographer had been distracted by use of her cell phone while performing radiography operations, and her head had been approximately 30 cm (12 inches) below the location of the source for about three minutes, while she set-up the next shot. After exiting the bay, she went to unlock the camera and crank-out the source, but then realized the camera was already unlocked and the source was still cranked out from the previous shot and was positioned inside the collimator. Although she reported carrying a survey meter, she did not perform a proper survey of the camera or the source guide tube after the previous shot. Additionally, another worker had opened a breaker that turned off ventilation fans in the building, but had been unaware that the same breaker also supplied power to the audible and flashing red light alarm for the fixed bay. Thus, when she entered the bay, the light and audible alarm were off and were not able to provide a warning that the source was still in the exposed position. After two reenactments were performed by the radiographer, a review of her mobile phone's call log, and her recollection of events, she believed her entire exposure during set-up to be two-and-a half minutes with her head below the source, and her entire time in the exposure bay to have been three minutes or less. Based on reenactments of the work activities, the highest exposure was to her head. The Radiation Safety Officer calculated the dose to the head at 81 mSv (8.1rem), bringing the radiographer’s total whole body dose for year 2012 to 82 mSv (8.2 rem). Dosimetry results indicated 10 mSv (1.0 rem) deep-dose equivalent (DDE). As a corrective action, the licensee implemented a new employee policy of banning the use of cell phones while performing radiography operations. The licensee also painted, labeled and locked the breaker box that supplied power to the fixed bay alarms.