Gamma Knife Incident Reported to the NRC from an Agreement State
An incident (EN44973) involving a Gamma Knife® was recently reported to the NRC from an Agreement State. During a patient treatment, the system experienced an Illegal Couch Sensor error causing the couch to partially retract out of the treatment position. When the licensee staff activated the Emergency Stop, the couch did not fully retract and the shielding doors remained open. The licensee staff then had to manually retract the couch and patient, and use the manual controls to close the shielding doors in order to place the system in a safe condition. Elekta states that this is a known software bug.
NRC is recommending that Gamma Knife® users review the emergency procedures. In the event of an Illegal Couch Sensor error, the Emergency Stop may not put the system in a safe condition. The operator will then need to manually retract the couch and use the manual controls to close the shielding doors.
To view this event and other event information, please visit NRC's event web page.