Source-detector trajectory optimization in cone-beam computed tomography: a comprehensive review on today’s state-of-the-art

Abstract

Cone-beam computed tomography (CBCT) imaging is becoming increasingly important for a wide range of applications such as image-guided surgery, image-guided radiation therapy as well as diagnostic imaging such as breast and orthopaedic imaging. The potential benefits of non-circular source-detector trajectories was recognized in early work to improve the completeness of CBCT sampling and extend the field of view (FOV). Another important feature of interventional imaging is that prior knowledge of patient anatomy such as a preoperative CBCT or prior CT is commonly available. This provides the opportunity to integrate such prior information into the image acquisition process by customized CBCT source-detector trajectories. Such customized trajectories can be designed in order to optimize task-specific imaging performance, providing intervention or patient-specific imaging settings. The recently developed robotic CBCT C-arms as well as novel multi-source CBCT imaging systems with additional degrees of freedom provide the possibility to largely expand the scanning geometries beyond the conventional circular source-detector trajectory. This recent development has inspired the research community to innovate enhanced image quality by modifying image geometry, as opposed to hardware or algorithms. The recently proposed techniques in this field facilitate image quality improvement, FOV extension, radiation dose reduction, metal artifact reduction as well as 3D imaging under kinematic constraints. Because of the great practical value and the increasing importance of CBCT imaging in image-guided therapy for clinical and preclinical applications as well as in industry, this paper focuses on the review and discussion of the available literature in the CBCT trajectory optimization field. To the best of our knowledge, this paper is the first study that provides an exhaustive literature review regarding customized CBCT algorithms and tries to update the community with the clarification of in-depth information on the current progress and future trends.

Revealing pelvic structures in the presence of metal hip prostheses via non-circular CBCT orbits

“…Despite the success of such interpolation algorithms, their ability to recapture fine structure located in close proximity to metal hardware remains a limiting factor. An alternative and complimentary method is to take advantage of the flexibility of modern robotic CBCT imaging systems and implement non-circular orbits that are designed to traverse in and out of the rotation plane, directly avoiding imaging through metal implants and surgical tools in the field of view [4][5][6][7] . For example, the ability of non-circular orbits to significantly reduce metal artifacts when imaging pedicle screws placed in the spine has been previously demonstrated on clinical imaging hardware 7,8 .…”

Cone-beam CT trajectory optimization for metal artifact avoidance using ellipsoidal object parameterizations

“…A general method to design metal artifact minimizing non-circular orbits has been proposed which treats projections through metal as missing data and maximizes sampling and data completeness [4]. Most customized trajectory planning algorithms rely on prior knowledge of the scene, such as a pre-operative CT or a known 3D model [5]. Instead of prior knowledge, another method predicts the next best view during the acquisition [6].…”

Technical note: Extended longitudinal and lateral 3D imaging with a continuous dual‐isocenter CBCT scan

“…This prevents 3D‐3D registration between the anatomy in the operating room with the anatomy in the planning images acquired prior to the procedure, as well as intraoperative assessment before the procedure is completed. To address these issues, efforts have been directed towards expanding the CBCT field‐of‐view 5 . However, most work completed to date on robotic CBCT systems has been focused on single direction expansion (i.e., only lateral or longitudinal expansion).…”

“…To address these issues, efforts have been directed towards expanding the CBCT field-of -view. 5 However, most work completed to date on robotic CBCT systems has been focused on single direction expansion (i.e., only lateral or longitudinal expansion). For example, lateral CBCT expansion on robotic CBCT systems has been previously demonstrated using offset 6 and rotated detector 7 configurations.…”