Dosimetric evaluation of a computed tomography treatment system

Pixel-by-pixel correction for tissue inhomogeneities was performed with a CT interfaced treatment planning system. The CT number for each pixel was converted to a physical density. Comparison of the resulting data with dose measurements in a RANDO phantom shows that pixel calculation overestimates dose by 5-7% at locations adjoining the lung, where loss of scatter is not taken into account by the algorithm. However, the new system does have some advantages over conventional treatment planning systems.