Four‐dimensional computed tomography (4DCT): A review of the current status and applications

Summary The applications of conventional computed tomography ( CT ) have been widely researched and implemented in clinical practice. A recent technological innovation in the field of CT is the emergence of four‐dimensional computed tomography ( 4DCT ), where a three‐dimensional computed tomography volume containing a moving structure is imaged over a period of time, creating a dynamic volume data set. 4DCT has previously been mainly utilised in the setting of radiation therapy planning, but with the development of wide field of view CT , 4DCT has opened major avenues in the diagnostic arena. The aim of this study is to provide a comprehensive narrative review of the literature regarding the current clinical applications of 4DCT . The applications reviewed include both routine diagnostic usage as well as an appraisal of the current research literature. A systematic review of the studies related to 4DCT was conducted. The Medline database was searched using the MeSH subject heading ‘ F our‐ D imensional C omputed T omography’. After excluding non‐human and non‐ E nglish papers, 2598 articles were found. Further exclusion criteria were applied, including date range (since wide field of view CT was introduced in 2007), and exclusion of technical/engineering/physics papers. Further filtration of papers included identification of Review papers. This process yielded 67 papers. Of these, exclusion of papers not specifically discussing 4 DCT (cone beam, 4 D models) yielded 38 papers. As part of the review, the technique for 4DCT is described, with perspectives as to how it has evolved and its benefits in different clinical indications.