Evaluation of the technical status of radiotherapy simulators involved in clinical trials

Abstract

Background

Radiotherapy simulators play an important role in the preparation of radiation treatment. Their mechanical and geometrical parameters have to be identical with those of the treatment machines. Therefore, quality control protocols for the simulators should be comprehensive and the tolerance limits as high as those for treatment machines.

Aim

Evaluation of the technical status of radiotherapy simulators involved in clinical trials.

Materials/Methods

In this paper, results of quality control tests conducted in 12 Polish radiotherapy centres are presented. The tests were carried out within the framework of Polish research project KBN No. 6 P05C 032 20. 12 radiotherapy simulators installed in Polish radiotherapy centres were thoroughly tested. In order to control technical conditions of the simulators, a set of 24 tests was elaborated. The tests were divided into six thematic groups. The detailed range of the parameters controlled and the accepted ranges of tolerance limits are given. The values of tolerance limits are based on data found in the available literature.

Results

The control of 12 simulators revealed the violation of accepted tolerance limits for 13 out of 24 controlled parameters. The most frequent violations of accepted tolerance limits occurred in the case of geometrical parameters of light simulation and mechanical parameters of the couch, both very important for the accuracy of the simulation process.

For 2 simulators almost 30% of controlled parameters were outside the tolerance limits.

Conclusions

The control of radiotherapy simulators undertaken within the framework of the clinical trial revealed that in the majority of cases the simulators were in good technical condition. In 2 cases almost 30% of controlled parameters were outside the tolerance limits. In such cases the manufacturers' service should be called urgently for necessary repairs and regulations. After repeated quality control tests a decision should be taken regarding the accepted range of operations which could be used in clinical practice. A QA and QC system for radiotherapy simulators should be introduced in each radiotherapy centre.