PRELIMINARY-RESULTS OF A QUALITY ASSURANCE NETWORK FOR RADIOTHERAPY CENTERS IN EUROPE

Based on the IAEA/WHO experience in mailed dosimetry, a Quality Assurance (QA) Network, sponsored by the EC committee ''Europe Against Cancer'', has been set up in 1991 for European centres, not involved in clinical research. Besides a survey of radiotherapy infrastructure, the project includes three measurement steps: primarily a check of beam output and quality in reference conditions with a mailed TLD-procedure, in a second step the mailed verification of other beam data and dose calculation procedures with a multipurpose phantom and finally in vivo dosimetry al the individual patient levels with mailed dosimeters. The results of infrastructure show good agreement with the data previously published by EORTC for research centres. Until January 1993, a total number of 37 centres (49 X-ray beams and 28 cobalt beams) from Belgium, France, Italy, The Netherlands, Sweden and The Czech and Slovak Republics have participated in the first measurement step. Deviations > 3% and < 6% from the stated dose are found in 17 out of the 79 checked beams. A deviation < 6% from the stated dose is detected in only I out of the 28 cobalt beams, but in 7 of the 49 X-ray beams. The large majority of the beams (23/25) with deviations > 3% belong to centres not having participated in external audits in the previous 5 years. A pilot study for the second step shows larger deviations in non reference conditions, especially for off-axis points and for oblique phantom surface. The third step has yet to be implemented. The initial stage of the project already demonstrates the usefulness of the programme especially for centres which have never before participated in external audits. Four more countries will join the programme and more centres are volunteering to participate than can be measured. A minimal central structure for the programme guarantees uniformity of procedures, interchangeable information, follow-up and joint resolution of specific technical problems.