A method for measuring component fractions in a multi-phase flow in a pipe (101, 201), the components forming conductive and/or non-conductive regions in the multi-phase flow, comprising the steps of: - collecting, from an Electric Inductance Tomography system with a plurality of electrodes (121, 131, 220) arranged evenly at the periphery of a cross-section of the pipe (101, 201), resistance measurement data and capacitance measurement data indicative of different areas of the cross-section of the pipe (101, 201), - collecting, from a Gamma Ray Tomography system with at least two gamma source-detector pairs (141-142, 241-242) arranged evenly at the periphery of a cross-section of the pipe (101, 201), gamma detector data, - determining a distribution of the conductive region based on the resistance measurement data, - determining a distribution of the non-conductive region based on the capacitance measurement data, - characterized by determining the fractions of components based on the distribution of the conductive region or non-conductive region corrected by gamma detector data in at least one iteration, wherein: a first estimate of the fraction of one of the components is determined based on the distribution of the conductive or non-conductive region and the first estimate of the fractions of the other components is determined based on the gamma detector data, the estimate of the fractions of the components is determined based on the gamma detector data that is iterated until the difference between estimates in consecutive iterations is below a predetermined threshold. - collecting, from an Electric Inductance Tomography system with a plurality of electrodes (121, 131, 220) arranged evenly at the periphery of a cross-section of the pipe (101, 201), resistance measurement data and capacitance measurement data indicative of different areas of the cross-section of the pipe (101, 201), - collecting, from a Gamma Ray Tomography system with at least two gamma source-detector pairs (141-142, 241-242) arranged evenly at the periphery of a cross-section of the pipe (101, 201), gamma detector data, - determining a distribution of the conductive region based on the resistance measurement data, - determining a distribution of the non-conductive region based on the capacitance measurement data, - characterized by determining the fractions of components based on the distribution of the conductive region or non-conductive region corrected by gamma detector data in at least one iteration, wherein: a first estimate of the fraction of one of the components is determined based on the distribution of the conductive or non-conductive region and the first estimate of the fractions of the other components is determined based on the gamma detector data, the estimate of the fractions of the components is determined based on the gamma detector data that is iterated until the difference between estimates in consecutive iterations is below a predetermined threshold. a first estimate of the fraction of one of the components is determined based on the distribution of the conductive or non-conductive region and the first estimate of the fractions of the other components is determined based on the gamma detector data, the estimate of the fractions of the components is determined based on the gamma detector data that is iterated until the difference between estimates in consecutive iterations is below a predetermined threshold.