Evolution of medical tomographic imaging - as seen from a Darwinian perspective

The development of medical tomographic imaging involves appearance of new imaging modalities, progressive change in (or loss of) the existing imaging modalities and devices, their divergence into special-purpose imagers and the convergence of different imaging modalities into devices of similar functions. These features closely resemble aspects of Darwinian evolution, which involves natural selection of inherited variability in life-forms. Thus, if imaging devices are the equivalent of life-forms, then sources of imager variability are imager designs or ideas, which could be considered to be the equivalent of genes; random appearance of new ideas - the equivalent of mutations; mass manufacture - the equivalent of reproduction; integration of different ideas - the equivalent of genetic recombination, the pressures exerted by the marketplace - the equivalent of natural selection. This hypothesis is explored by comparing aspects of the evolution of X-ray, radionuclide, ultrasound, magnetic resonance and several other tomographic imaging modalities. It may be of interest to apply this Darwinian model to help direct the current increasing emphasis on targeted and translational research and in weighting the relative roles of industry, clinical users and academic non-targeted "basic" research.