DOSIMETRIC EVALUATION OF THE SIEMENS VIRTUAL WEDGE SYSTEM

"A virtual wedge system", which was recently released by Siemens Oncology Care Systems, has been installed in our Mevatron KD-2 linear accelerators. Siemens Virtual Wedge System is a software/hardware system that allows delivery of a wedge-shaped dose distribution without using a physical wedge during radiation treatment. In this system, one of the collimator jaws moves with a constant speed from almost closed to open field size and produces a dose distribution that is similar to that of a physical wedge. Monitor unit versus jaw position tables have been calculated analytically for each field size. This analytical approach makes the arbitrary wedge angles and asymmetric fields possible. Measurements have been taken in order to evaluate virtual wedge's dosimetrie properties. Percentage depth dose curves were found to be similiar to open field curves and dose profiles along the wedge were similiar to the physical wedge one. 6 MV photon beam fields have been evaluated in this paper.