Radiotherapy error detection by treatment verification sheet

Abstract

Purpose: This study was undertaken to investigate errors in radiation therapy process using the treatment verification sheet as a medium for error detection. Materials and methods: Treatment verification sheets were attached to the patient’s file folder. Each physicist checked and marked the dosimetric part of the treatment verification sheets of each individual patient before transferring the plan to the treatment room. Technologists verified and marked the treatment verification sheets of all the treatment parameters from the radiation oncologist’s prescription chart and treatment plan report before starting the first fraction of treatment. This verification was repeated every week during the whole course of the treatment. All the errors found were corrected immediately, collected and analyzed after the course of treatment had been completed. Results: From May 2010 to February 2012, 1,136 cases were verified. We detected the treatment parameter errors in 150 cases (13.2%). Seventy-one cases (47.3%) out of the errors were from mismatches between the radiation oncologist’s prescription chart and the treatment plan report. However, these errors did not result in significant incorrect dose to the target volume. One case received a 33.7% higher than the intended dose to the skin due to bolus misplacement. There were 2 cases (1.3%) resulted in serious dose errors to the target volumes. These errors were from incorrect dose calculation of Source Axis Distance (SAD) instead of Source Skin Distance (SSD) setting, resulting in maximum dose error of 11.5% under-dosage from the prescribed dose. Conclusion: The treatment verification sheet is a good method for error detection and correction in radiotherapy process. It is easy to perform and early edited before treatment execution.