2023
Pekel, Erdal
X-ray Computed Tomography with a Robotic Sample Holder PhD Thesis
Technische Universität München, 2023.
Abstract | Links | BibTeX | Tags:
@phdthesis{dissertation,
title = {X-ray Computed Tomography with a Robotic Sample Holder},
author = {Erdal Pekel},
url = {https://mediatum.ub.tum.de/?id=1712965},
year = {2023},
date = {2023-12-08},
urldate = {2023-12-08},
pages = {155},
school = {Technische Universität München},
abstract = {We present a robotic sample holder that offers superior flexibility for X-ray computed tomography compared to conventional, static sample mounting mechanisms. We introduce a suitable calibration algorithm and an intermediate, custom designed gripper part that improves the reach of the arm. We also develop a trajectory optimization routine that reduces radiation dose and measurement time and improves reconstruction image quality at runtime without prior knowledge about the measured sample.},
keywords = {},
pubstate = {published},
tppubtype = {phdthesis}
}
We present a robotic sample holder that offers superior flexibility for X-ray computed tomography compared to conventional, static sample mounting mechanisms. We introduce a suitable calibration algorithm and an intermediate, custom designed gripper part that improves the reach of the arm. We also develop a trajectory optimization routine that reduces radiation dose and measurement time and improves reconstruction image quality at runtime without prior knowledge about the measured sample.
Pekel, Erdal; Lavilla, María Lancho; Pfeiffer, Franz; Lasser, Tobias
Runtime optimization of acquisition trajectories for x-ray computed tomography with a robotic sample holder Journal Article
In: Engineering Research Express, vol. 5, no. 4, pp. 045058, 2023.
Abstract | Links | BibTeX | Tags:
@article{Pekel_2023b,
title = {Runtime optimization of acquisition trajectories for x-ray computed tomography with a robotic sample holder},
author = {Erdal Pekel and María Lancho Lavilla and Franz Pfeiffer and Tobias Lasser},
url = {https://dx.doi.org/10.1088/2631-8695/ad08fd},
doi = {10.1088/2631-8695/ad08fd},
year = {2023},
date = {2023-11-01},
journal = {Engineering Research Express},
volume = {5},
number = {4},
pages = {045058},
publisher = {IOP Publishing},
abstract = {Tomographic imaging systems are expected to work with a wide range of samples that house complex structures and challenging material compositions, which can influence image quality in a bad way. Complex samples increase total measurement duration and may introduce beam-hardening artifacts that lead to poor reconstruction image quality. This work presents an online trajectory optimization method for an x-ray computed tomography system with a robotic sample holder. The proposed method reduces measurement time and increases reconstruction image quality by generating an optimized spherical trajectory for the given sample without prior knowledge. The trajectory is generated successively at runtime based on intermediate sample measurements. We present experimental results with the robotic sample holder where two sample measurements using an optimized spherical trajectory achieve improved reconstruction quality compared to a conventional spherical trajectory. Our results demonstrate the ability of our system to increase reconstruction image quality and avoid artifacts at runtime when no prior information about the sample is provided.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Tomographic imaging systems are expected to work with a wide range of samples that house complex structures and challenging material compositions, which can influence image quality in a bad way. Complex samples increase total measurement duration and may introduce beam-hardening artifacts that lead to poor reconstruction image quality. This work presents an online trajectory optimization method for an x-ray computed tomography system with a robotic sample holder. The proposed method reduces measurement time and increases reconstruction image quality by generating an optimized spherical trajectory for the given sample without prior knowledge. The trajectory is generated successively at runtime based on intermediate sample measurements. We present experimental results with the robotic sample holder where two sample measurements using an optimized spherical trajectory achieve improved reconstruction quality compared to a conventional spherical trajectory. Our results demonstrate the ability of our system to increase reconstruction image quality and avoid artifacts at runtime when no prior information about the sample is provided.
Pekel, Erdal; Dierolf, Martin; Pfeiffer, Franz; Lasser, Tobias
Spherical acquisition trajectories for x-ray computed tomography with a robotic sample holder Journal Article
In: Engineering Research Express, vol. 5, no. 3, pp. 035045, 2023.
Abstract | Links | BibTeX | Tags:
@article{Pekel_2023,
title = {Spherical acquisition trajectories for x-ray computed tomography with a robotic sample holder},
author = {Erdal Pekel and Martin Dierolf and Franz Pfeiffer and Tobias Lasser},
url = {https://dx.doi.org/10.1088/2631-8695/acefad},
doi = {10.1088/2631-8695/acefad},
year = {2023},
date = {2023-08-01},
urldate = {2023-08-01},
journal = {Engineering Research Express},
volume = {5},
number = {3},
pages = {035045},
publisher = {IOP Publishing},
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.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
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.
M. Dierolf E. Pekel, F. Pfeiffer
Spherical acquisition trajectories for X-ray Computed Tomography with a robotic sample holder Conference
Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine (Fully 3D), Stony Brook, USA, 2023.
@conference{Pekel2023,
title = {Spherical acquisition trajectories for X-ray Computed Tomography with a robotic sample holder},
author = {E. Pekel, M. Dierolf, F. Pfeiffer, T. Lasser},
year = {2023},
date = {2023-07-16},
urldate = {2023-07-16},
booktitle = {Fully Three-Dimensional Image Reconstruction in Radiology and Nuclear Medicine (Fully 3D)},
address = {Stony Brook, USA},
abstract = {In this work we present an X-ray computed tomography setup that integrates a seven degree of freedom robotic arm as a sample holder. The path planning and robot control algorithms are optimized for seamless execution of spherical trajectories. A precision manufactured sample holder part is attached to the robotic arm for the calibration procedure. We present experimental results with the robotic sample holder where a sample measurement on a spherical trajectory achieves superior reconstruction quality compared to a conventional circular trajectory. The proposed system is a step towards higher image reconstruction quality in X-ray CT systems.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
In this work we present an X-ray computed tomography setup that integrates a seven degree of freedom robotic arm as a sample holder. The path planning and robot control algorithms are optimized for seamless execution of spherical trajectories. A precision manufactured sample holder part is attached to the robotic arm for the calibration procedure. We present experimental results with the robotic sample holder where a sample measurement on a spherical trajectory achieves superior reconstruction quality compared to a conventional circular trajectory. The proposed system is a step towards higher image reconstruction quality in X-ray CT systems.
2022
Pekel, Erdal; Schaff, Florian; Dierolf, Martin; Pfeiffer, Franz; Lasser, Tobias
Geometric calibration of seven degree of freedom robotic sample holder for x-ray CT Conference
7th International Conference on Image Formation in X-Ray Computed Tomography, Baltimore, USA, 2022.
Abstract | Links | BibTeX | Tags:
@conference{ctmeeting2022,
title = {Geometric calibration of seven degree of freedom robotic sample holder for x-ray CT},
author = {Erdal Pekel and Florian Schaff and Martin Dierolf and Franz Pfeiffer and Tobias Lasser},
url = {https://doi.org/10.1117/12.2646492},
doi = {10.1117/12.2646492},
year = {2022},
date = {2022-10-17},
urldate = {2022-10-17},
booktitle = {7th International Conference on Image Formation in X-Ray Computed Tomography},
address = {Baltimore, USA},
abstract = {We present a geometric calibration method for integrating a seven degrees of freedom robotic arm as a sample holder within an existing laboratory X-ray computed tomography setup. We aim to provide a flexible sample holder that is able to execute non-standard and task-specific trajectories for complex samples. The calibration is necessary to identify the accurate pose of the sample which deviates from the expected pose due to inaccurate placement of the robotic arm. The robotic arm is integrated with a unified software package that allows for path planning, collision detection, geometric calibration and reconstruction of the sample. With our software the user is able to command the robotic arm to execute arbitrary trajectories for a given sample in a safe manner and output its reconstruction to the user. We present experimental results with a circular trajectory where the robotic sample holder achieves identical visual quality compared to a conventional sample holder.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
We present a geometric calibration method for integrating a seven degrees of freedom robotic arm as a sample holder within an existing laboratory X-ray computed tomography setup. We aim to provide a flexible sample holder that is able to execute non-standard and task-specific trajectories for complex samples. The calibration is necessary to identify the accurate pose of the sample which deviates from the expected pose due to inaccurate placement of the robotic arm. The robotic arm is integrated with a unified software package that allows for path planning, collision detection, geometric calibration and reconstruction of the sample. With our software the user is able to command the robotic arm to execute arbitrary trajectories for a given sample in a safe manner and output its reconstruction to the user. We present experimental results with a circular trajectory where the robotic sample holder achieves identical visual quality compared to a conventional sample holder.
Pekel, Erdal; Schaff, Florian; Dierolf, Martin; Pfeiffer, Franz; Lasser, Tobias
X-ray computed tomography with seven degree of freedom robotic sample holder Journal Article
In: Engineering Research Express, vol. 4, no. 3, 2022.
Abstract | Links | BibTeX | Tags:
@article{10.1088/2631-8695/ac8224,
title = {X-ray computed tomography with seven degree of freedom robotic sample holder},
author = {Erdal Pekel and Florian Schaff and Martin Dierolf and Franz Pfeiffer and Tobias Lasser},
url = {http://iopscience.iop.org/article/10.1088/2631-8695/ac8224},
doi = {10.1088/2631-8695/ac8224},
year = {2022},
date = {2022-08-05},
urldate = {2022-08-05},
journal = {Engineering Research Express},
volume = {4},
number = {3},
abstract = {We present an X-ray Computed Tomography setup that integrates a seven degrees of freedom robotic arm as a sample holder within an existing laboratory X-ray computed tomography setup. We aim to provide a flexible sample holder that is able to execute non-standard and task-specific trajectories for complex samples. The robotic arm is integrated with a unified software package that allows for path planning, collision detection, geometric calibration and reconstruction of the sample. The calibration is necessary to identify the accurate pose of the sample which deviates from the expected pose due to inaccurate placement of the robotic arm. With our software the user is able to command the robotic arm to execute arbitrary trajectories for a given sample in a safe manner and output its reconstruction to the user. We present experimental results with a circular trajectory where the robotic sample holder achieves identical visual quality compared to a conventional sample holder.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present an X-ray Computed Tomography setup that integrates a seven degrees of freedom robotic arm as a sample holder within an existing laboratory X-ray computed tomography setup. We aim to provide a flexible sample holder that is able to execute non-standard and task-specific trajectories for complex samples. The robotic arm is integrated with a unified software package that allows for path planning, collision detection, geometric calibration and reconstruction of the sample. The calibration is necessary to identify the accurate pose of the sample which deviates from the expected pose due to inaccurate placement of the robotic arm. With our software the user is able to command the robotic arm to execute arbitrary trajectories for a given sample in a safe manner and output its reconstruction to the user. We present experimental results with a circular trajectory where the robotic sample holder achieves identical visual quality compared to a conventional sample holder.
2020
Pekel, Erdal; Dierolf, Martin; Pfeiffer, Franz; Lasser, Tobias
X-ray Computed Tomography with a Robotic Sample Holder Conference
International Conference on Image Formation in X-ray Computed Tomography (CT Meeting), Regensburg, Germany, 2020.
Abstract | Links | BibTeX | Tags:
@conference{ctmeeting2020,
title = {X-ray Computed Tomography with a Robotic Sample Holder},
author = {Erdal Pekel and Martin Dierolf and Franz Pfeiffer and Tobias Lasser},
url = {https://ct-meeting.org/wp-content/uploads/2021/11/ProceedingsCTMeeting2020.pdf},
year = {2020},
date = {2020-08-03},
urldate = {2020-08-03},
booktitle = {International Conference on Image Formation in X-ray Computed Tomography (CT Meeting)},
address = {Regensburg, Germany},
abstract = {In this work we present the integration of a robotic arm with seven degrees of freedom as a sample holder within an experimental X-ray computed tomography setup. The robot enables arbitrary rotations of the sample and hence different non-standard acquisition trajectories that are not possible with conventional sample holding mechanisms. Our framework provides a programmatic interface for trajectory inputs and their motion planning, a robotic arm calibration mechanism for accurate target placement utilizing a single RGB camera, and both passive and active collision detection mechanisms based on a set of depth cameras. We elaborate on the challenges of precisely positioning samples into the X-ray beam and propose a method together with a discussion on its current limitations, in particular in view of performing X-ray computed tomography.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
In this work we present the integration of a robotic arm with seven degrees of freedom as a sample holder within an experimental X-ray computed tomography setup. The robot enables arbitrary rotations of the sample and hence different non-standard acquisition trajectories that are not possible with conventional sample holding mechanisms. Our framework provides a programmatic interface for trajectory inputs and their motion planning, a robotic arm calibration mechanism for accurate target placement utilizing a single RGB camera, and both passive and active collision detection mechanisms based on a set of depth cameras. We elaborate on the challenges of precisely positioning samples into the X-ray beam and propose a method together with a discussion on its current limitations, in particular in view of performing X-ray computed tomography.