Abstract: The present disclosure relates to the field of imaging phantoms and their use in computed tomography (CT) and radiotherapy (RT). In particular, the present disclosure provides novel ink compositions conferring radiation absorbing properties mimicking biological tissue to imaging phantoms. Thus, these novel ink compositions are particularly useful for creating tissue equivalent imaging phantoms, which allow realistically simulating biological tissue over the whole range of photon energies relevant for applications in CT and RT. Accordingly, the present disclosure also provides novel imaging phantoms exhibiting radiation absorbing properties mimicking real biological tissue. The present disclosure further relates to methods of generating imaging phantoms built up of layers making use of the novel ink compositions disclosed herein.