Potential and limitations of invariant kernel conformal therapy.

A treatment planning methodology was developed to investigate the invariant kernel form of conformal therapy proposed by Brahme. Three-dimensional dose distributions were calculated by convolving a rotationally symmetric, invariant kernel with weighting distributions. Fourier transform convolution techniques implemented on an array processor were used to achieve high calculation speeds, thereby allowing iterative techniques in the spatial and frequency domains for computing dose distributions that asymptotically approach a desired dose distribution. To use rotationally symmetric kernels, the generality of the solution is traded for a fast, deterministic, inverse planning approach. The limitations imposed on the dose distributions by this loss of generality are characterized and tentative conclusions are drawn about the potentials and limits of clinical application of this form of the methodology. Further developments of the concept are suggested.