SXR cross-sectional distributions measured in the European reversed field pinch (RFP) experiment RFX by means of a tomographic diagnostic are described. Various reconstruction techniques have been compared. A correction technique to minimize the systematic effect due to the non-identical thicknesses of the material filters has been developed. A number of experimental situations have been explored, and a study of the correlation between the MHD and SXR properties of the plasma has been made. The analysis concentrates both on standard discharges and on the recently discovered quasi-single-helicity states, whose signature is the growth of a sizeable m = 1 structure in the emissivity distributions. Detailed imaging of the plasma in these conditions is presented.