Many-view under-sampling (MVUS) technique for low-dose CT

In computed tomography (CT) imaging, radiation dose delivered to the patient is one of the major concerns. Among many technical solutions to lowering radiation dose while preserving clinical utilities of the images, sparse-view CT is promising technique. However, a fast power switching of an X-ray tube, which is needed for the sparse-view sampling, can be challenging in many CT systems. We have recently proposed a novel alternative approach to sparse-view circular CT that can be readily incorporated on the existing CT systems, and have successfully shown its feasibility. Instead of switching the X-ray tube power, one can place an oscillating multi-slit collimator between the X-ray tube and the patient to partially block the X-ray beam thereby reducing the radiation. In this study, an experimental study was performed to evaluate the performance of the proposed XT scan scheme. Industrial CT projection data of a CatPhan® 600 phantom was acquired by use of the oscillating multi-slit collimator. We used a sinusoidal motion of the collimator to the perpendicular direction of the rotation axis for the purpose of obtaining more uniform spatial sampling of the image. For image reconstruction, we used a total-variation minimization (TV) algorithm which has shown its out-performance in many sparse-view CT applications.