Cone-beam CT with a noncircular (sine-on-sphere) orbit: imaging performance of a clinical system for image-guided interventions

Abstract

To compare the image quality characteristics of a cone-beam CT (CBCT) imaging system with noncircular scan protocols (Sine-on-Sphere) to a conventional circular orbit. A phantom was used to assess image uniformity, image noise, and noise-power spectrum (NPS) for a biplane C-arm (Icono; Siemens Healthineers) that could perform CBCT with either a circular or non-circular orbit (Sine-on-Sphere, “SineSpin”). The non-circular orbit used a sinusoidal motion with an amplitude of ±10º during the orbit. Uniformity and quantum noise were similar for the circular and non-circular orbits. A slight increase in cupping artifact for the noncircular orbit was observed and attributed to slightly increased path lengths (increased scatter-to-primary ratio) for oblique rays through the cylindrical phantom. The NPS clearly depicted closing of the “null cone” about the fz spatial frequency axis owing to improved sampling with the non-circular orbit. A non-circular orbit for CBCT resulted in improved sampling with similar noise magnitude and uniformity compared to a circular orbit.