Consistency in quality control programmes for electron accelerators in radiotherapy centres

Abstract

Background and purpose: To gain insight into the current practice of quality control (QC) of medical electron accelerators and to reduce possible variations in test frequencies and test procedures. Materials and methods: An extensive questionnaire on QC procedures of medical electron accelerators was distributed and completed by all (21) radiotherapy institutions in The Netherlands. The questions were related to safety systems, mechanical parameters, beam profiles, beam energy, absolute dosimetry, wedge filters, the dose monitor system and radiation leakage. Results: The data of the questionnaire were compared with recommendations given in national and international reports on QC of electron accelerators. Large variations in time spent on QC exist, especially for accelerators having dual energy photon beams and several electron beam energies. This diversity is mainly due to differences in philosophy with regard to QC and the differences in resources and machine time available. Furthermore, large variations in test frequencies and test methodologies were observed. The staffing level involved in the QC measurements was evaluated and compared with recent recommendations provided by EFOMP-ESTRO. Conclusions: From these recommendations and the results of the questionnaire, a set of minimum guidelines for a QC programme could be formulated and implemented in all radiotherapy institutions in The Netherlands.