Lateral Electronic Disequilibrium in FFT Convolution Dose Calculationsz

In high energy photon dose calculations, electron transport is an important process especially in low density regions such as lung. Electron transport is captured in time consuming algorithms such as Monte Carlo, scaling of the primary kernels, etc., but not in the eecient FFT convolution dose calculation. We do not want to scale the kernels in order to take advantage of the FFT-we continue to use the water kernels in the inhomogeneous medium. Can we incorporate eeectively such a process into the FFT dose calculation? z The postscript version of this article can be retrieved from