Quality assurance of Siemen's virtual wedge(TM)by using film dosimetry

A film dosi netry method is proposed for measuring the non-uniform dose distribution generated by Virtual Wedges of a 6 MV Siemens Pr mus accelerator. This method was chosen due to the dose integration capabilities and the improved spatial resolution that films offer, giving the opportunity of measuring dose distribution in a single beam irradiation. Dose profiles were obtained and analyzed using a 16-bit Vidar film scanner and OmniPro-Accept software. Results were compared with corresponding ones measured with an array ionization chamber for both virtual and conventional wedges. A good agreement was found between the two methods for all the examined wedge angles. This study shows that film, dosimetry can be incorporated in a monthly quality asseurance program for virtual wedges in order to reduce the required effort.