Quality assurance control in the EORTC cooperative group of radiotherapy. 3. Intercomparison in an anatomical phantom.

Two papers concerning the quality control study organised by the EORTC (European Organisation for Research on Treatment of Cancer) Cooperative Group on Radiotherapy have been published. The medical profile (part 1) and the dosimetric intercomparison (part 2) of the participating institutions were presented. This part (paper 3) presents an integrated clinical and dosimetric investigation in an anatomical phantom. A tonsillar tumour and a homolateral subdigastric node were marked in an anatomical phantom. The institutions were asked to treat the phantom once like an ordinary patient. The phantom was loaded with dosimeters and irradiated. From the results obtained, it can be concluded that we did not find any major dosimetric problem related to absorbed dose calibration or calculation in the phantom. However, several major problems were related to non-optimal planning, treatment technique and dose distribution. The investigation shows the importance of a quality assurance programme for cooperative groups.