New PhD on "The possibilities of reducing radiation dose and improve image quality in CT diagnostics using advanced image processing"

On December 20 2011 Cand.scient. Anne Catrine Trægde Martinsen from The Intervention Centre defended her PhD thesis at Faculty of Medicine, University of Oslo. The trial lecture was held on the 19th with the topic: Can reduced radiation doses in CT scans by use of advanced image processing improve health benefit? On the image from left: Dr Per Kristian Hol, Oslo University Hospital, professor Per Hjalmar Nakstad, Institute for Clinical Medicine, University of Oslo, Dr Gaute Hagen, Oslo University Hospital, Anne Catrine Trægde Martinsen, PhD, Docent Anders Tingberg, Skånes University Hospital Malmø, Sweden, Dr Ellen Schlichting, Oslo University Hospital

Abstract:CT scanners have been more complex both with respect to scanner design and reconstruction techniques. Fast scan times and large coverage enables new types of CT-examinations like cardiac CT, organ perfusion and CT colonography, causing an increase in performed numbers of CT scans. In radiology, CT scans are associated with high patient doses. According to the Norwegian radiation protection authority there has been an increase in the total population radiation exposure in Norway related to CT examinations from 65% in 2002 to 80% in 2008. The benefit of an accurate diagnosis must be balanced against radiation risk. Optimization of CT examinations with respect to diagnostic performance and radiation dose is a legal requirement in Norway. In this study, the impact of both adaptive statistical iterative reconstruction (ASIR) and image postprocessing filters like SharpView on diagnostic performance and the reliability of using absolute HU for diagnostic purposes were evaluated. The results showed that dose reduction of 30-50% for CT liver examinations was possible with new reconstruction techniques, and a substantial interscanner variations in HU were demonstrated. Our results indicated that the use of absolute HU should be used with caution for diagnostic purposes, and new reconstruction- and post-processing filter may be useful tools in improving the diagnostic performance and at the same time reducing the radiation dose from CT.