In cases where the effect of interest changes the direction of the incoming radiation, the image pixels are no longer decoupled and the sample has to be scanned sequentially using a small focused beam to avoid the information from different regions of the sample being convoluted irreversibly. This chapter describes such scanning methods. Three examples are presented: tomography using fluorescent X-ray radiation, tomography exploiting the absorption fine structure near the absorption edges, and tomography utilizing small-angle scattering from mesoscopic structures within the sample.
Keywords: fluorescence tomography, X-ray absorption tomography, small-angle scattering tomography, image pixels, mesoscopic structures