This event involved an
HDR brachytherapy unit [Varian Medical Systems, Inc. Model GammaMed plus, serial number E159; with sealed source Model GammaMed 232, serial number 24-07-4445-004-082504-11622-71 (connector serial number D24E445)]. The female patients larynx cancer treatment plan called for four
HDR brachytherapy treatments. On October 26, 2004, two
HDR brachytherapy treatments were given. Before the third treatment was to be given, on October 27, 2004, an error was discovered. The prescribing physician stopped the treatment until dosimetry information was completed. The third treatment was not given. The error was caused because a circular tool was used to mark the treatment site. The diameter of the circle was used when the radius should have been applied. As a result, the area treated was 2 cm away from the defined locus instead of 1 cm. The total source length treated was 11 cm, (approximately 1 cm diameter cylinder surrounding the
brachytherapy source placed inside a tracheotomy tube). The prescribed dose was 500 cGy (centiGray) to the entire 11 cm length. The worse case patient dose scenario was that the patient received 2,756 cGy at one dwell position out of 23 dwell positions along the 11 cm treatment length. The dose delivered would have been 551% greater than the prescribed dose at the position respective to the worst-case scenario. The licensee does not anticipate any adverse health affects to the patient. The
Utah Division of Radiation Control is currently investigating this event.