Comparison study of image quality between filtered back projection and iterative reconstruction algorithm for dose reduction in chest CT

Many studies have shown that iterative reconstruction (IR) algorithm is possible to make the tube current and/or voltage in CT imaging lower without a major loss of image quality. However, there are not many studies on the acquisition conditions for low dose CT images using IR algorithm to achieve the same image quality as routine dose images using FBP algorithm. The aim of this study was to investigate the image quality of low dose CT images obtained with IR algorithm. Images were reconstructed with filtered back projection (FBP) and iDose(4) hybrid IR algorithm (Philips Healthcare, Cleveland, OH). CTDIvol for routine protocol and low dose protocol were 5.2 mGy, and 2 mGy, respectively. Images were quantitatively assessed through Hounsfield unit (HU), noise power spectrum (NPS) and contrast to noise ratio (CNR). The results showed that image quality of iDose4 algorithm was improved than that of FBP algorithm. When the same low-dose protocol is used, the IR algorithm provided improved imaging performance compared with the FBP algorithm, and also demonstrated that IR algorithm provides potential for maintaining or improving image quality with much less radiation dose than FBP algorithm with routine dose.