Towards the exploitation of phase effects in clinical synchrotron radiation radiology

The so-called “phase contrast imaging” has been widely investigated by several researchers during the last years. The scientific community is currently convinced that this technique can provide relevant improvements with respect to conventional techniques based on absorption effects, and the first clinical studies are now on the way. Among the three main phase contrast imaging set-ups (interferometry and diffraction-enhanced imaging, both based on the use of crystals, and free space propagation), the last one is probably the simplest and the most straightforward. Hence, the Trieste group has recently upgraded his SYnchrotron Radiation for MEdical Physics (SYRMEP) beamline and will soon be able to perform the first phase contrast mammographic investigations on human patients using this modality, in the framework of the project “Synchrotron X-ray Mammography: Clinical Experimentation”. In this context, it is therefore important to focus on the actual exploitation of phase effects, outlining the extent to which clinical mammography can concretely benefit from the beam spatial coherence. First of all, some side effects connected with the use of the different set-ups will be taken into account and compared. Secondly, some basic issues connected with the detection of calcifications and masses will be addressed. Finally, the concepts of “edge” and “area” contrasts will be critically reviewed, showing among other things that in some cases an effective “area” contrast due to phase effects can effectively be achieved for small objects.