Analysis of Medical Events in High-Dose-Rate Brachytherapy

Abstract

The present study reviews medical events (MEs) in high-dose-rate brachytherapy in order to understand the nature of these events and to investigate how to prevent the occurrences of errors in HDR brachytherapy procedures. MEs in HDR brachytherapy reported to the Nuclear Regulatory Commission (NRC) or agreement states from January 1999 to December 2011 are reviewed and divided into five categories based on the nature of the events. From 1999 to 2011, a total of 137 medical event reports involving 181 patients were recorded in the NRC database. The events consist of: (i) wrong treatment site; (ii) treatment planning error; (iii) treatment delivery error; (iv) failure in source retraction mechanism, and (iv) others. The most frequent cause of MEs in HDR brachytherapy is the use of incorrect catheter/transfer tube length (approximately 42%), resulting in missing treatment targets by distances ranging from 4 mm to 30 cm. Unlike permanent brachytherapy in which treatment deliveries can be verified with post-implant dosimetry, errors in HDR brachytherapy can go undetected for multiple fractions or patients. Mistakes can still happen even when a well-established procedure is correctly followed, such as the incorrect measurement of catheter length due to obstruction. A test run using film should be performed for each type of treatment technique to confirm the geometric accuracy. In-vivo dosimetry can be utilized in the first fraction to detect gross target miss or planning error in the early stage of a treatment course.