A CT scanner apparatus includes an X-ray source mounted on a gantry of the CT scanner apparatus and configured to emit X-rays, and at least one magnetic field gradient circuit. The at least one magnetic field gradient circuit and the X-ray source rotate together. The CT scanner apparatus also includes a CT detector mounted on the gantry in fixed orbital opposition to the X-ray source. The CT detector is configured to detect the X-rays, wherein the CT detector and the X-ray source are configured to rotate along a first orbital path. The CT scanner apparatus also includes an array of fixed PCD assemblies arranged in a ring inside the first orbital path. Each PCD assembly is configured to rotatably actuate about a gantry support from a first position to a second position to reduce blockage of emitted X-rays when the magnetic field gradient circuit rotates within a predetermined distance of the PCD assembly.
