Dynamic platform for moving organ imaging

A multimodality platform (CT, PET, Radiotherapy) has been developed in order to move phantoms (maximum weight: 70kg). This allows the study of the influence of motion on image quality. The translation system (160 mm in the z axis, maximal speed of 50 mm × s -1 ) was controlled by a computer via a NI Motion Controller PCI 7344 (National Instrument, TX, USA). As an initial experiment, an anthropomorphic cardiac CT phantom (QRM, Moehrendorf, Germany) was moved linearly with speeds of 5, 10 and 20 mm × s -1 . Acquisitions were done on a Siemens Somatom Volume Zoom CT Scanner. To compare dynamic and static images, mutual information, correlation coefficient, standard deviation, volume computation and radiologist scoring were conducted. The mean position error of the platform was 0.1mm ± 0.04. Automatic evaluation of the image quality and/or the blurring is not easy. As predicted, we found an increase in artifacts with the speed of the phantom. The platform allows us to simulate physiological motions (respiratory and cardiac) in order to study their real influence on image quality and to correct them. We can already produce z axis physiological motion with the platform. More degrees of freedom (y and z rotations, x and y translations) will be added to improve the simulation of physiological motions.