A review of NRC medical event reports related to brachytherapy, 2005-2024

We analyzed the Nuclear Regulatory Commission event notifications related to brachytherapy events that occurred between January 1, 2005, and December 31, 2024. The events were categorized and their distribution and time evolution analyzed.

A total of 818 events (227 LDR, 203 HDR, 21 intravascular, 367 microsphere) were identified, excluding events that related purely to shipping. We analyzed the events for the whole period and in consecutive 5-year intervals. The total number of events rose by 27% from the first to the last interval (2005-09:179, 2020-24:227), with the LDR events decreasing by 81% (2005-2009:98, 2020-24: 19) and microsphere events increasing by 588% (2005-09:25, 2020-24:172). HDR events decreased by 15% (2005-09:53, 2020-24:45), while intravascular events increased (2005-09:3, 2020-2024:7) but stayed very rare. . For HDR, the three most frequent categories were treatment planning error (26%), transfer tube issues (13%) and other/unknown issues (13%); the frequency of treatment planning events decreased with time (2005-09: 38%, 2020-24: 18%). For LDR, the three most frequent categories were lost or leaking source (39%), other/unknown issues (24%) and permanent implant sources implanted into wrong tissue (18%). For microspheres, most events were related to the sphere remaining in the delivery apparatus and for intravascular brachytherapy, to the source not retracting. The radioisotopes of LDR events were I-125 (72%), Pd-103 (11%), Cs-137 (8%), Ir-192 (4%), Cs-131 (3%) and Sr-90 (2%); no events relating to Ir-192 or Cs-137 occurred in 2020-24.

The reduction in the LDR events is probably explained by the decreased frequency of prostate implants and LDR gynecological procedures. Microspheres now account for most event reports.