In Silico Investigation of an Innovative Cone-Beam CT Configuration for Quantitative Imaging

Quantitative evaluations in 3D images acquired via Cone-Beam Computed Tomography (CBCT) are limited by the scatter abundance and cone-beam artifacts. This work investigates benefits in using an innovative scanning geometry in CBCT (eCT), which replaces each projection of the conventional scanning protocol with a series of collimated projections (Np) acquired over an oscillating trajectory, realized either with an oscillating source or a multi-spot array. In silico tests employed a cylindrical water phantom embodying inserts of four biological materials. 1 mm-thick bone slabs were sandwiched between 9 mm water slabs to evaluate the image conspicuity. eCT improved the Hounsfield Unit (HU) accuracy, with a direct relation with Np. eCT with Np = 10 reduced the bias of the estimated HU more than two times when compared to CBCT. Increasing the Np presented a large impact on the image conspicuity for portions of the field of view (FOV) distant from the central axial plane, with the signal-to-noise ratio between water and bone slabs increasing by a factor of 18 for Np = 10 compared to CBCT. The proposed eCT configuration is expected to be adopted in applications without strict demand for scanning time and projection number, such as dentomaxillofacial and intrasurgical imaging, imaging of the extremities, and image-guided radiotherapy.