A bibliometric and social network analysis perspective of X-ray phase-contrast imaging in medical imaging

Introduction: Phase-contrast imaging (PCI) is a novel technology that can visualise variations in X-ray refraction (phase contrast) in addition to differences in X-ray attenuation (absorption contrast). Compared to radiography using conventional methods (i.e. absorption-based imaging), PCI techniques can potentially produce images with higher contrast-to-noise ratio and superior spatial resolution at the same or lower radiation doses. This has led PCI to be explored for implementation in medical imaging. While interest in this research field is increasing, the whole body of PCI research in medical imaging has been under-investigated. This paper provides an overview of PCI literature and then focusses on evaluating its development within the scope of medical imaging. Methods: Bibliographic data between 1995 and 2018 were used to visualise collaboration networks between countries, institutions and authors. Social network analysis techniques were implemented to measure these networks in terms of centrality and cohesion. These techniques also assisted in the exploration of underlying research paradigms of clinical X-ray PCI investigations. Results: Forty-one countries, 592 institutions and 2073 authors contributed 796 investigations towards clinical PCI research. The most influential contributors and network collaboration characteristics were identified. Italy was the most influential country, with the European Synchrotron Radiation Facility being the most influential institution. At an author level, F. Pfeiffer was found to be the most influential researcher. Among various PCI techniques, grating interferometry was the most investigated, while computed tomography was the most frequently examined modality. Conclusions: By gaining an understanding of collaborations and trends within clinical X-ray PCI research, the links between existing collaborators were identified, which can aid future collaborations between emerging and established collaborators. Moreover, exploring the paradigm of past investigations can shape future research - well-researched PCI techniques may be studied to bring X-ray PCI closer to clinical implementation, or the potential of seldom-investigated techniques may be explored.