Clinical evaluation of an algorithm for inhomogeneity corrections of electron beam dosimetry

An algorithm for inhomogeneity correction of electron beam dose distributions has been developed at U.T. M. D. Anderson Hospital and Tumor Institute. The enhanced perturbation of the electron beam requires a more rigorous and exact analysis compared to megavoltage photon beams. The algorithm uses a pencil beam calculation model to correct for air gap, tissue inhomogeneity and field shape. Cross sectional computer tomography data provide surface contour and tissue inhomogeneity information. The accuracy of the calculation model has been verified by TLD measurements in tissue substitute phantoms reconstructed from CT patient scans.