Spherical acquisition trajectories for x-ray computed tomography with a robotic sample holder

Abstract

This work presents methods for the seamless execution of arbitrary spherical trajectories with a seven-degree-of-freedom robotic arm as a sample holder.
 The sample holder is integrated into an existing X-ray computed tomography setup.
 We optimized the path planning and robot control algorithms for the seamless execution of spherical trajectories.
 A precision-manufactured sample holder part is attached to the robotic arm for the calibration procedure.
 Different designs of this part are tested and compared to each other for optimal coverage of trajectories and reconstruction image quality.

 We present experimental results with the robotic sample holder where a sample measurement on a spherical trajectory achieves improved reconstruction quality compared to a conventional circular trajectory.
 Our results demonstrate the superiority of the discussed system as it outperforms single-axis systems by reaching nearly 82\% of all possible rotations.

 The proposed system is a step towards higher image reconstruction quality in flexible X-ray CT systems.
 It will enable reduced scan times and radiation dose exposure with task-specific trajectories in the future, as it can capture information from various sample angles.

Runtime optimization of acquisition trajectories for x-ray computed tomography with a robotic sample holder

“…After introducing the simulation environment and an overview of the optimization pipeline, we describe more specific aspects like reconstruction volume segmentation, score update, and trajectory pose sampling. We also refer interested readers to our previous publications [1,2] for a more detailed introduction to the robotic sample holder for x-ray CT.…”

“…We based our simulation environment on the software package demonstrated in [1] and [2]. The simulation integrates the FRANKA EMIKA Panda robotic arm with suitable motion planning and x-ray computed tomography components in a unified software package.…”

“…Reachability is a well-defined but complex metric dependent on a range of factors, such as the physical properties of the arm and its operating environment. We extensively study the reachability of the seven DoF robotic arms for a wide range of operating conditions in our previous work [2].…”

“…In recent work, we introduced a flexible robotic arm with seven degrees of freedom (DoF) as a sample holder within a laboratory x-ray computed tomography (CT) setup [1]. Subsequently, we provided an extensive study on our system's ability to execute spherical trajectories [2]. The arm adds flexibility to the setup as a sample holder by enabling arbitrary rotations and placement of the sample.…”

“…In this work, we use the results from our previous publications (see [1,2]) to improve reconstruction image quality further when using the seven DoF robotic arm as a sample holder by introducing optimized spherical trajectories. We aim to introduce a method that is easy to use and does not require prior knowledge about the provided sample.…”