Dose reduction in oncological staging multidetector CT: effect of iterative reconstruction

Abstract

To compare radiation exposure and image quality of oncological staging multidetector CT (MDCT) examinations of the chest, abdomen and pelvis with and without iterative reconstruction (IR). 40 patients with known malignancy underwent staging CT examinations at two time points. Both CT scans were performed on the same scanner (SOMATOM® Definition Flash, Siemens Healthcare, Forchheim, Germany). For the baseline scan, the tube current-time product was set to 250 mAs [image reconstruction: filtered back projection (FBP)] and for the follow-up scan to 150 mAs [reconstruction: iterative reconstruction (IR)]. Effective radiation doses were estimated based on dose-length products for both baseline and follow-up. Noise measurements in defined regions were compared for FBP and IR. Images were also subjectively evaluated for image quality by three radiologists with different levels of experience. Dose reduction was 44.4±8.2% for reduced-dose CT scans with IR compared with baseline with FBP. Image noise was not significantly different between images reconstructed with FBP and IR. The subjective quality of standard-dose FBP images and reduced-dose iteratively reconstructed CT images were identical. Our results show the dose-reducing potential of IR of CT image data in oncological patients. The algorithm tested in the present scientific study allows a >45% dose reduction at maintained image quality.