Automatic intraoperative stitching of nonoverlapping cone‐beam CT acquisitions

Abstract

Purpose Cone-Beam Computed Tomography (CBCT) is one of the primary imaging modalities in radiation therapy, dentistry, and orthopedic interventions. While CBCT provides crucial intraoperative information, it is bounded by a limited imaging volume, resulting in reduced effectiveness. This paper introduces an approach allowing real-time intraoperative stitching of overlapping and non-overlapping CBCT volumes to enable 3D measurements on large anatomical structures. Methods A CBCT-capable mobile C-arm is augmented with a Red-Green-Blue-Depth (RGBD) camera. An off-line co-calibration of the two imaging modalities results in co-registered video, infrared, and X-ray views of the surgical scene. Then, automatic stitching of multiple small, non-overlapping CBCT volumes is possible by recovering the relative motion of the C-arm with respect to the patient based on the camera observations. We propose three methods to recover the relative pose: RGB-based tracking of visual markers that are placed near the surgical site, RGBD-based simultaneous localization and mapping (SLAM) of the surgical scene which incorporates both color and depth information for pose estimation, and surface tracking of the patient using only depth data provided by the RGBD sensor. Results On an animal cadaver, we show stitching errors as low as 0.33 mm, 0.91 mm, and 1.72mm when the visual marker, RGBD SLAM, and surface data are used for tracking, respectively. Conclusions The proposed method overcomes one of the major limitations of CBCT C-arm systems by integrating vision-based tracking and expanding the imaging volume without any intraoperative use of calibration grids or external tracking systems. We believe this solution to be most appropriate for 3D intraoperative verification of several orthopedic procedures.

Computer‐aided Design of Distal Femoral Osteotomy for the Valgus Knee and Effect of Correction Angle on Joint Loading by Finite Element Analysis

“…The goal of DFO is to restore the balance of loading between two compartments of the knee. 22 , 23 Performing DFO for correcting valgus deformity is a good surgical option for severe cases. 2 , 24 , 25 Shivji et al .…”

“…The goal of DFO is to restore the balance of loading between two compartments of the knee. 22,23 Performing DFO for correcting valgus deformity is a good surgical option for severe cases. 2,24,25 Shivji et al 26 reported that 86 patients with an average age of 48 years were treated with DFO due to valgus knee deformity combined with lateralcompartment OA.…”

Automatic Registration and Error Color Maps to Improve Accuracy for Navigated Bone Tumor Surgery Using Intraoperative Cone-Beam CT

“…The mean separation of our UTTs, at 9.9 cm, facilitated a minimal TRE. Ensuring that the UTT registration spheres lie completely within the CBCT volume (in this study, 25 × 25 × 18 cm) may be challenging in obese patients or those with large, deep tumors; however, 1 possible solution would be to automatically stitch together 2 acquisitions to encompass a larger volume 40 . Using 1 UTT provided wide coverage but the spheres did not encircle the target, leading to a higher TRE of >1 mm (Fig.…”

From Perspective X-ray Imaging to Parallax-Robust Orthographic Stitching

“…With the availability of 3D intra-operative imaging, instead of 2D X-ray image stitching, recent works suggested stitching of tomographic volumes reconstructed from X-ray images acquired on a circular trajectory [10,9]. While volumetric data do not suffer from the effects of parallax and can, therefore, be stitched easily, circular shortscans required for 3D tomographic reconstruction expose the patient to much higher radiation doses compared to simple X-ray acquisitions, suggesting that these methods are best employed only once, e.g., for verification.…”