“…Although the technology of such detectors has not yet reached the same level of maturity as the one used in conventional imaging (CT, SPECT, PET), scientists have proposed and studied in the last decades different bi-dimensional systems, called Compton scattering tomography (CST), see e.g. [23,27,7,1,3,5,6,8,12,13,16,19,25,4,17,30]. It is also possible to consider interior sources, for instance via the insertion of radiotracers like in SPECT.…”