On October 26, 2006 an incident regarding a high-dose rate (
HDR) mammosite treatment was discovered.
At approximately 15:00 hours the physicist was verifying source positions and dwell times prior to treatment number eight of ten. The physicist noted that the first (most distal) source position was different from previous treatments (94.5 cm vs. 92.3 cm). When he queried the dosimetrists about the change, he was told that a different value was given for the measurement of the overall catheter length. The measured catheter length for the first seven treatments was 96.6 cm, while the most recent measurement gave 96.75 cm. The dosimetrist entered 95.15 cm (subtracting the 1.6 cm correction factor for the actual position of the most distal source dwell point within the catheter). However, this did not explain a 2.2 cm different in the first dwell position.
The subsequent investigation into the discrepancy revealed that the usable catheter length entered into the planning computer was 93.0 cm rather than the correct value of 95 cm. This erroneous usable catheter length was used for the first seven treatments, which resulted in an unplanned dose to tissue proximal to the mammosite balloon. It is presently believed that a typographical error occurred in entering the usable catheter length into the treatment planning computer that was the root cause of the unplanned dose.
The referring physician and patient have been notified of the event. The authorized user (radiation oncologist) is currently evaluating the clinical status of the patient. Further treatments are on hold pending a clinical decision.
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.
- * * UPDATE FROM C. FLANNERY (FSME) TO W. GOTT AT 1641 ON 10/27/06 * * *
This event has been reviewed by the NRC medical review committee and determined to be a reportable medical event.