Background and purpose: A geometric check procedure of the reconstruction techniques used in brachytherapy treatment planning systems was developed by the EQUAL (European Quality Laboratory) Laboratory in the framework of the ESTRO's (European Society for Therapeutic Radiology and Oncology) project 'ESQUIRE' (Education Science and QUality assurance In Radiotherapy in Europe [Baumann M, Brada M. Towards equity in turbulent Europe ESTRO, European cooperation and the European Commission. Radiother Oncol 2005;75:251-2. Heeren G. The bright but ephemeral life of a rainbow. A chronical of seventeen years of intensive ESTRO-EU cooperation. Radiother Oncol 2005;75:253-7]) by the task group Braphyqs (Brachytherapy physics quality system).
Patients and methods: The check is performed by using the so-called 'Baltas' phantom, mailed to the participating centres in order to check the local technique of geometric reconstruction used in dose calculation.
Results: To validate the procedures, the check was first tested among the members of the Braphyqs Network. Since November 2002, the system is open to other centres. Until now 152 reconstructions have been checked. Eighty-six percent of the results were within an acceptance level after the first check. For the remaining 14%, a second check has been proposed. The results of the re-checks are in most cases within an acceptance level, except for 2% of the reconstructions.
Conclusions: The geometric check is available from the EQUAL Laboratory for all the brachytherapy centres. The decrease of the deviations observed between the two checks demonstrates the importance of this kind of external audit as some errors were revealed, which were not discovered before with techniques used in clinical quality control routines.