Multisource x-ray system for artifact reduction in dedicated breast CT

Abstract

This study examines the potential of a multisource x-ray system to reduce cone beam artifacts in a dedicated breast CT acquisition geometry. A breast CT scanner (Doheny), built at our institution, was used to demonstrate the potential of multiple x-ray sources in a single x-ray tube housing. Both 3 focal spot and 5 focal spot thermionic systems were physically simulated in this study. The x-ray tube is mounted on a vertical actuator on the breast CT system gantry, allowing the single x-ray source to be positioned at different vertical locations in the field of view. Five acquisition geometries were used to acquire raw cone beam CT data with the x-ray source locations placed at 2 cm intervals. Data was collected using a 15-cm tall Defrise phantom. The individual acquisitions of raw CT data were reconstructed using filtered back projection, aligned and summed. The reconstructed CT volume data set using three sources and five sources were compared to that produced from a single source. Both multi-source datasets demonstrated less visible cone beam artifact, and the contrast clearly improved. The resolvable field of view in the vertical direction was extended by 50% when comparing the one source to the three source geometry and extended by 120% when comparing the one source to the five source geometry. This physical simulation of a multisource x-ray CT system successfully demonstrated that a reduction in cone beam CT artifacts could be achieved using a multi-source x-ray tube on a breast CT scanner.