Dose optimization in adult pet imaging: a balance between patient exposure and image quality. Literature review and future perspectives

Purpose: the aim of our study is to collect all the measures adopted in clinical daily practice to reduce the patient dose in the different steps (injected activity, CT protocol, reconstruction methods, etc.) and to explore their advantages and limitations. Methods: a comprehensive search of relevant articles was conducted in medical databases (i.e. Embase, Scopus, Web of Science and Medline), using the keywords: dose optimization, computed tomography, PET, radiopharmaceutical, PET/CT, PET/MRI, DRL. Only English and full-text articles were included, without limitations on the year of publication. Results: after the screening, 58 articles were selected that were considered eligible for the analysis. The methods used for dose optimization include: improving reconstruction algorithms; reducing the injected radiotracer activity but increasing the acquisition times, especially in new digital PET scanner; using long-axial field of view (LAFOV) PET/CT tomographs; and modulating CT radiation dose by using artificial intelligence tools. All these approaches are in line with those implemented in our departments. Furthermore, the future trend is prioritizing data collection, in accordance with international guidelines, to better understand PET/CT dose discrepancies while also striving to optimize radiation doses without compromising the quality of PET images. Conclusions: several optimization methods have been developed and implemented to reduce the dose delivered to the patients who undergo PET/CT or PET/MRI examination; in recent years, the advent of digital PET and LAFOV scanners has been an important step in the evolution of molecular imaging and dose optimization and there has also been an increasingly widespread adoption in clinical practice.