NMSS-0018: Problems Encountered When Manually Editing Treatment Planning Data on Nucletron Microselectron-HDR Model 105.999

DESCRIPTION

Two misadministrations resulted when a licensee manually edited treatment data for the Nucletron HDR unit. While attempting to manually edit one parameter, unintended and unnoticed changes to the source step size occurred that caused the misadministration. The unintended changes occurred when the licensee attempted to select the dwell positions to be edited, by the inappropriate use of the "Tab" and "arrow" keys,

the other (unrelated) treatment plan parameters were changed. The licensee did not expect those parameters to change. This expectation was reinforced by the lack of any cautions or other instructions, in the Nucletron MicroSelectron-HDR v1.2X manual, that would indicate otherwise. More importantly, the licensee expected to see a confirmation message that would have required it to acknowledge any changes to the treatment plan step size, in accordance with the information on page 4-23 of the user's manual. Secondly, since the licensee did not anticipate that any of the other treatment plan parameters would change, it did not check any parameters other than the source dwell times on the final printed treatment plan.

In order to address this issue,[1]the staff proposed to issue an information notice to all medical licensees authorized to conduct high-dose-rate (HDR) remote afterloading brachytherapy treatments. Furthermore, the staff proposed to work with the FDA and the State of Maryland to have the manufacturer modify the software. Rulemaking or other actions were to be considered if the effort to have the software modified was unsuccessful.

CONCLUSION

Information Notice 99-09[2]was issued to inform medical licensees of the potential problems. The issue was resolved when NRC verified that the manufacturer corrected the software problem.