Search

Purpose: A dummy run was organized to test the compliance of participating centres with the guidelines of EORTC protocol 22931, which compares high dose radiotherapy with concomitant radiochemotherapy in a postoperative setting for patients presenting with locally advanced head and neck carcinomas., Methods: In a first step the participants (seven centres, six replies) were asked to define the planning target volume (PTV) in a given patient on the basis of clinical, surgical and radiological (CT-images) data-sets and according to the protocol guidelines. In a second phase a series of CT-reconstructed slices with on- and off-axis PTV outlines were sent to 11 centres (10 replies), which were asked to plan a treatment following the recommendations made in the frame of the trial., Results: The first step of this dummy run emphasized wide intercentre variations in PTV extensions. This fact raises the question of the reproducibility when pooling patients in multicentric trials. The second step indicated a large variability in the field arrangements which was left to the discretion of the investigators. Only three out of 10 of the institutions followed the ICRU 50 recommendations for dose reporting. Moreover, protocol requirements were not met for dose distribution homogeneity in any centre., Conclusions: In order to reduce intercentre treatment heterogeneities, several actions have been taken by the EORTC Radiotherapy Group, e.g. amendments have been brought to protocol 22931 regarding a better definition of clinical and planning target volumes. Furthermore, a stricter application of the ICRU 50 recommendations for dose reporting has been sought.

The safe application of ionising radiation for diagnosis and therapy requires a high level of knowledge of the underlying processes and of quality assurance. Sophisticated modern equipment can be used effectively for complicated diagnostic and therapeutic techniques only with adequate physics support. In the light of recent analyses and recommendations by national and international societies a joint working group of representatives from ESTRO (European Society for Therapeutic Radiology and Oncology) and from EFOMP (European Federation of Organisations for Medical Physics) was set up to assess the necessary staffing levels for physics support to radiotherapy. The method used to assess the staffing levels, the resulting recommendations and examples of their practical application are described.

The results of a dummy run involving nine centers participating in a study comparing radiotherapy alone with radiotherapy plus hormone therapy in patients with high metastatic risk prostatic cancer (EORTC protocol 22863) show that, in all centers but one, patients are treated in the same way. However, they have also indicated that protocol compliance could be improved by a better assessment of the target volume, by taking into account of the use of protective shields and of variations in radiological density, by determining beam position on a large number of slices, and by the use of CT scan images for treatment planning.

The concept of a Master Protocol for phase III studies was raised at the Steering Committee of the EORTC Radiotherapy Group, in order to make the work of the study coordinators easier, when writing protocols and to give them more homogeneity. The Master Protocol defines and clarifies in a logical order the different steps which must be taken when designing a randomized trial--from the rationale to the references. It pays particular attention to eligibility criteria, volumes of interest defined in agreement with ICRU Report 50 (gross tumor volume, clinical target volume, planning target volume and organs at risk), simulation procedure, treatment technique, normal tissue sparing, dose computation, equipment, dose specification (also in agreement with ICRU Report 50). Last but not least, the different procedures of quality assurance for protocols and patients are also defined (site visits, dummy run procedure, in vivo dosimetry, individual case review) to allow working plans to be made in advance. We are aware that this work is not exhaustive, but hope that the contents will be of help to those who are writing a protocol.

The question of optimal portal separation between two contiguous fields is of importance in radiotherapy. An analytical linear model based on experimental data has been developed for a Co-60 unit (Siemens Gammatron S 65 K). It allows the computation of the separation distance for any combination of field sizes not necessarily having the same source-surface-distance, defined either with penumbra trimmers or focused shaping blocks.