On Dose Reduction and View Number in Computed Tomography

The ultimate goal in improving computed tomography (CT) technology is to reconstruct higher quality images with lower radiation dose, which can help to lower cancer risks to the patients. Inspired by the compressive sensing (CS) theory, few-view reconstruction has been a hot topic for dose reduction in recent years. However, when the radiation dose is fixed, fewer view projections does not always imply higher image quality. Numerical tests are performed in this study to investigate the relationship between image quality and view numbers under a fixed radiation dose level. It is observed that for a fixed dose level, as the view number increases, the image quality increases but then decreases once the view number is sufficiently large. For the dose level and phantom we tested, the optimal view number for best reconstruction quality is around 300 in an equi-angular full scan configuration, which provides a useful hint for practical applications.