In many industrial applications, non-invasive measurements of different flows play an important role. For flows consisting of only one phase, such as water or gas, there are several methods available. Most of these methods, however, are not applicable to multiphase flows, such as paper fiber suspensions or iron ore slurries. The overall goal of this project was to investigate the use of ultrasound tomography for measuring particle distributions and particle mass fractions in multiphase flows. We use a custom-made ultrasound transmitter and receiver array manufactured from PVDF (polyvinylidene fluoride) film. The first part gives an overview of two tomography methods, the filter back projection and the Fourier reconstruction. Then we show with experiments how the reconstructed image can be used to extract information about particle mass fraction as well as particle distribution in a multiphase flow consisting of iron ore powder and water. The results are compared with those obtained from conventional attenuation measurements, and show that we can extract additional information with this technique