A new analytical model for Varian enhanced dynamic wedge factors.

Dynamic and physical (hard) wedges are used in 3D conformal radiotherapy in order to improve dose distribution in patients. Unlike wedge factors for physical wedges that depend on wedge material and thickness, wedge factors for Varian dynamic wedges depend on the relationship between the position of the moving jaw and the number of delivered monitor units. In this study, we describe a new analytical model for dynamic wedge factors. We also review the existing analytical models and compare calculated and measured wedge factors. The comparison is performed for different wedge angles, symmetric and asymmetric fields and two different photon energies. The obtained results indicate that the new dynamic wedge model provides the best overall agreement (within 1%) with the measured wedge factors.