A source localization principle for linear shift-invariant systems with application to point optical and radioactive sources

The source localization principle is an inequality between the means of scalar fields produced by different sources in any linear shift-invariant system. This principle is presented here as a pair of conditions (spatial and temporal) under which a point source produces a greater mean field over finite source-centered regions than all other sources. Biomedical applications involving point optical sources and radioactive sources are discussed.