The following was received from the state of
New Jersey via email:
While treating a patient with a gamma-knife icon unit, there was an apparent activation of the emergency stop. No one admits to touching the emergency stop button, but the sources retracted, the unit doors remained open, and the table functions were frozen. One of the authorized medical physicists (AMP) entered the room and manually retracted the table from the unit, as per emergency procedures. The licensee reported that this is the protocol when the emergency (red) console button is pushed. The AMP and one of the authorized users (AU) helped the patient off the table. The couch lever was pushed back into place and the unit was reset so the doors would close.
The AMP observed the treatment time at the back of the unit. The AMP repeated the sector position check of the unit without incident. The licensee contacted the device manufacturer, Elekta, about the incident. They reported that Elekta informed them it was acceptable to proceed and complete the patient treatment. They then resumed and completed the patient's treatment without further incident. The events were documented in the patient's record.
The manufacturer sent a service technician to the licensee the next day (i.e., today, October 4, 2022) to inspect the unit, make any needed repairs and check the log files. After review of the logs, the
AMP and Elekta believe patient movement triggered the incident. The dose to the
AMP and
AU was estimated to be 0.134 mrem. This was not a medical event, since the planned treatment was completed.