New Scanning Technique Using Adaptive Statistical Iteractive Reconstruction (ASIR) Significantly Reduced the Radiation Dose of Cardiac CT

Abstract

Introduction: This study aimed to evaluate the effect of applying Adaptive Statistical Iteractive Reconstruction (ASIR) technique on the radiation dose of cardiac CT.Methods: This was a single centre retrospective observational study looking at all cardiac CT cases archived in our PACS system from 2009 to date. CT scan mode, peak kilovolt (kVp), tube current (mA) and dose length product (DLP) and patient demographics details and scanned heart rate were collected. Quality of scan (good or fair) was determined by two cardiac CT reporters in consensus. All cardiac CT were performed with GE 64-slice CT scanners. Scanning with ASIR was introduced to all scanners on 15th December 2010. All studies were then subcategorised into two cohorts, pre-ASIR and post ASIR. Continuous variables were compared using nonparametric Kruskal-Wallis test while categorical variables were compared using Chi-Square analysis.Results: There were 424 cardiac CT studies were included in this study. There were 368 studies in the pre-ASIR cohort and 54 studies in the post-ASIR. There were no significant different between two cohorts in terms of patients' age and gender, scanned heart rate, kVp and scanned range. However, there were significantly less mA used in the post-ASIR cohort in comparison with pre-ASIR cohort (median tube current 580 mA vs 650 mA respectively, p < 0.001). This has resulted in significant reduction of radiation dose (DLP) in the post-ASIR cohort in comparison with the pre-ASIR cohort (420 mGy/cm vs 585 mGy/cm respectively, p < 0.001). There was no significant difference in the proportion of study with good image quality (76% vs 78%, respectively, p = 0.711).Conclusion: Our preliminary results show that application of ASIR helps to reduce the radiation dose of cardiac CT by nearly 30% without affecting the image quality.