Background and purpose: Due to the increased complexity of the radiotherapy process in recent years, many QA procedures have been introduced to improve the quality of the treatment preparation and the treatment delivery. Most of these procedures give no direct information on the efficiency of the overall process in the radiotherapy department. It is quite evident that the frequency of errors will affect the efficiency of the process (for instance manpower to solve the detected problems), but also affect more generally the patients' experience.

Material and methods: To make some objective assessment of the erroneous entries in the process of radiotherapy, a pilot study was initiated to report all problems during a period of 2 months on a dedicated QA form. By registration of these errors, the QA group could trace the main sources of the decrease in efficiency and increased waiting time for patients.

Results and conclusions: For 46% of the patients during the two months at least one QA forms was filled in. With these QA forms 198 erroneous entries including 33 erroneous treatments were reported. Regarding the origin of the problems, the majority (60%) were generated in the planning process, while 56% of the errors were detected at the treatment unit before or during delivery of the first fraction. In total 461 actions were undertaken to recover all the reported errors. This generated time delay for 145 patients. Extrapolating these results to a year, a 0.7 full time equivalent person is spent to recover these errors, while the total patient population waits for about 140 hours. Corrective actions have been undertaken to optimise the overall process.