Projection-based dynamic tomography.

This paper proposes a 4D dynamic tomography framework that allows a moving sample to be imaged in a tomograph as well as the associated space-time kinematics to be measured with nothing more than a single conventional x-ray scan. The method exploits the consistency of the projection/reconstruction operations through a multi-scale procedure. The procedure is composed of two main parts solved alternatively: a motion-compensated reconstruction algorithm and a projection-based measurement procedure that estimates the displacement field directly on each individual projection. The method is applied to two studies: a numerical simulation of breathing from chest computed tomography (CT) and a clinical cone beam CT of a breathing patient acquired for image-guidance of radiotherapy. The reconstructed volume, initially blurred by the motion, is cleaned from motion artifacts. It results in an improved reconstruction quality showing sharper edges and finer details.