Feasibility of CT-based 3D anatomic mapping with a scanning-beam digital x-ray (SBDX) system

Abstract

This study investigates the feasibility of obtaining CT-derived 3D surfaces from data provided by the scanning-beam digital x-ray (SBDX) system. Simulated SBDX short-scan acquisitions of a Shepp-Logan and a thorax phantom containing a high contrast spherical volume were generated. 3D reconstructions were performed using a penalized weighted least squares method with total variation regularization (PWLS-TV), as well as a more efficient variant employing gridding of projection data to parallel rays (gPWLS-TV). Voxel noise, edge blurring, and surface accuracy were compared to gridded filtered back projection (gFBP). PWLS reconstruction of a noise-free reduced-size Shepp-Logan phantom had 1.4% rRMSE. In noisy gPWLS-TV reconstructions of a reduced-size thorax phantom, 99% of points on the segmented sphere perimeter were within 0.33, 0.47, and 0.70 mm of the ground truth, respectively, for fluences comparable to imaging through 18.0, 27.2, and 34.6 cm acrylic. Surface accuracies of gFBP and gPWLS-TV were similar at high fluences, while gPWLS-TV offered improvement at the lowest fluence. The gPWLS-TV voxel noise was reduced by 60% relative to gFBP, on average. High-contrast linespread functions measured 1.25 mm and 0.96 mm (FWHM) for gPWLS-TV and gFBP. In a simulation of gated and truncated projection data from a full-sized thorax, gPWLS-TV reconstruction yielded segmented surface points which were within 1.41 mm of ground truth. Results support the feasibility of 3D surface segmentation with SBDX. Further investigation of artifacts caused by data truncation and patient motion is warranted.

Single-view geometric calibration for C-arm inverse geometry CT

“…Recently, the feasibility of CT-based 3-D cardiac chamber mapping with SBDX was demonstrated through numerical simulations. 7 , 8 An SBDX-derived cardiac chamber surface map could potentially be displayed along with the real-time SBDX 3-D catheter tracking results to facilitate device navigation during an interventional procedure, such as radiofrequency catheter ablation for atrial fibrillation. In practical C-arm-based inverse geometry CT (IGCT), uncertainties in the imaging geometry may exist due to manufacturing tolerances, nonideal source and detector alignment, or C-arm deflection during rotation.…”

A geometric calibration method for inverse geometry computed tomography using P-matrices

“…6 In practical C-arm based inverse geometry CT, uncertainties in the imaging geometry may exist due to manufacturing tolerances, non-ideal source and detector alignment, or C-arm deflection during rotation. An incorrect mapping between the assumed 3D object coordinate system and the projection acquisition system has been shown to degrade spatial resolution and can introduce image artifacts.…”