A women was prescribed a breast cancer treatment using an
HDR mammosite balloon
brachytherapy. The dose was delivered in 10 fractions using
Iridium - 192 seeds. During administration of the first fraction, the physicist received an alarm from the
HDR computer, the alarm was overridden based on the judgment of the physicist at the time of the event and the treatment was completed. Additional fraction treatments were also completed as intended.
Subsequent review of the first treatment and the cause of the alarm indicated that a medical event may have occurred. The alarm was indicating that the seed placement was dislodged by 2 centimeters. The physicist thought at the time that the alarm was indicating the seed dislodged by only 2 millimeters. The treatment calculations were revisited and the dislodgment of the seed by 2 centimeters put the seed at the skin entry point of the application catheter. This resulted in an under dose to the target site and an overdose to the skin. Preliminary calculations estimate that the skin in a 7 mm diameter around the catheter entry point may have received a dose of 3700 centigrays based on the strength of the seed (4.47 curies) and the dwell time.
The patient will be notified of the event. The patient's doctor will continue to monitor the skin for any ill effects.
A "Medical Event" may indicate potential problems in a medical facility's use of radioactive materials. It does not necessarily result in harm to the patient.