Complexity index (COMIX) and not type of treatment predicts undetected errors in radiotherapy planning and delivery

Background and Purpose: Quality assurance procedures (QA) may reduce the risk of errors in radiotherapy. The aim of this study was to assess a QA program based on independent check (IC) procedures in patients undergoing 3D, intensity modulated (IMRT) and extracranial stereotactic (ESRT) radiotherapy. Materials and methods: IC for set-up (IC1) and for radiotherapy treatments (IC2) was tested on 622 patients over a year. Fifteen events/parameters and 17 parameters were verified by V and IC2, respectively. A third evaluation check (IC3) was performed before treatment. Potential errors were classified based on their magnitude. Incidents involving only incorrect or incomplete documentation were segregated. Treatments were classified based on a complexity index (COMIX). Results: With IC1, 75 documentation incidents and 31 potential errors were checked, and with IC2 111 documentation incidents and 6 potential errors were checked. During the study period 10 errors undetected by standard procedures (IC1, IC2) were detected by chance or by IC3. The incidence of errors and serious errors undetected by standard procedures was 1.6% and 0.6%, respectively. There was no higher incidence of errors undetected in patients undergoing IMRT or ESRT, while there was a higher incidence of errors undetected in more complex treatments (p < 0.001). Conclusions: Systematic QA procedures can reduce the risk of errors. The risk of errors undetected by standard procedures is not correlated with the treatment technological level (3D versus IMRT/ESRT). (C) 2008 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 89 (2008) 320-329.