Refraction and small-angle scattering can provide unique imaging signals in situations where absorption- or other attenuation-based effects are insufficient. Attenuation contrast is low in cases where either the absolute values of the attenuation coefficients of the individual components of the object are low, or the differences between the various components are small. In such cases, other contrast mechanisms have to be employed for imaging such as the phase contrast described in the previous chapter. This chapter discusses two additional contrast mechanisms: refraction tomography and small-angle scattering tomography. Experimental results for both techniques are presented.
Keywords: refraction tomography, small-angle scattering, contrast, absorption-based effects, attenuation-based effects