[Safety in radiotherapy: Control of software and informatics systems]

The development of computerized systems in radiotherapy opens new challenging possibilities. There is however a major risk of specific errors if the use of such systems is not properly controlled. On the other hand, the software sophistication, such as encountered in modern treatment planning systems (TPS), makes it very difficult to set up efficient quality assurance programs compatible with the workload of users in charge of daily routine. From the analysis of previous accidents involving TPS, we can conclude that the major risks are erroneous calculations of monitor units resulting from a poor understanding of the software capabilities combined to a lack of vigilance with respect to the data obtained from a computer. To reduce the risks, it is necessary to setup a comprehensive quality assurance program covering all steps of the process, including commissioning of a new system and systematic checks of individual treatment plans. Such a program offers the users the opportunity to acquire a deeper understanding of the system and avoid potential pitfalls. There is presently a lack of consensus for an international protocol related to quality assurance of computerized systems in radiotherapy. It is therefore important to define protocols at the national level, with special consideration of the aspects which are more likely to generate significant errors.