Non-circular CBCT orbit design and realization on a clinical robotic C-arm for metal artifact reduction

Yiqun, Q.; Gang, Grace J.; Ehtiati, Tina; Reynolds, Tess; Russ, Tom; Wang, Wenying; Weiss, Clifford R.; Theodore, Nicholas; Hong, Kelvin; Siewerdsen, Jeffrey H.; Stayman, J. Webster

doi:10.1117/12.2612448

Cited by 8 publications

(18 citation statements)

References 8 publications

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“…Previously, we have investigated several types of non-circular orbits that can largely eliminate metal artifacts including sinusoidal and multiple-arc trajectories. [5][6][7] In this work we consider simplified versions of two orbit types: sawtooth orbits and double-circle-plus-arc (DCArc) orbits. (See Figure 1).…”

Section: Orbit Design and Implementationmentioning

confidence: 99%

“…The test bench includes an X-ray tube (Varex Rad-94), a flat-panel detector (Varex PaxScan 4343CB), a 6 degree-of-freedom (DoF) hexapod (PI H-900K Series) and rotation stage (PI PRS-200) (Figure 2), which enables precise emulation of arbitrary source-detector trajectories. In previous work, 7 inaccuracies in positioning of a Siemens Artis Zeego were identified. We found systematic inaccuracies in the system encoded positions in LAO/RAO angle, CRAN/CAUD angle, isocenter, and a slight in-plane panel rotation around its normal axis, but also found that the C-arm was sufficiently rigid that we could assume a fixed source-detector distance and piercing point.…”

Section: Bench Experiments Implementationmentioning

confidence: 99%

“…We found systematic inaccuracies in the system encoded positions in LAO/RAO angle, CRAN/CAUD angle, isocenter, and a slight in-plane panel rotation around its normal axis, but also found that the C-arm was sufficiently rigid that we could assume a fixed source-detector distance and piercing point. 7,9 In our bench studies, we emulated a C-arm system whose source remained fixed relative to the detector but had similar isocenter shifts and angular inaccuracies. These inaccuracies were added to an ideal sawtooth orbit (Figure 1A) and were realized by the hexapod using 3 DoF linear motions and 3 DoF rotations in roll, pitch, and yaw.…”

Section: Bench Experiments Implementationmentioning

confidence: 99%

“…robotic C-arms) have enabled the exploration of more advanced non-circular orbits for added benefits including increased field-of-view (FOV) size, 1 improved image quality and/or dose reduction, 2 weight-bearing extremity imaging, 3 and metal artifact reduction. [4][5][6][7] Despite the increased interest, non-circular orbits that require more complex motion remain difficult to implement and research on clinical systems. There are several challenges -especially when many new orbits are desired including those that are customized to be patient-and/or task-specific.…”

Section: Introductionmentioning

confidence: 99%

“…To date, we have relied on largely manual controls to achieve non-circular orbits on robotic C-arms. 4,7,8 Second, the manual element in the data acquisition leads to irreproducible scans. Additionally, the system geometry parameters recorded by the robot are not accurate enough to be used for 3D reconstructions due to system vibrations and gravity-induced strain on mechanical parts.…”

Section: Introductionmentioning

confidence: 99%

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Practical workflow for arbitrary non-circular orbits for CT with clinical robotic C-arms

Yiqun

Gang²,

Reynolds³

et al. 2022

7th International Conference on Image Formation in X-Ray Computed Tomography

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Non-circular orbits in cone-beam CT (CBCT) imaging are increasingly being studied for potential benefits in field-of-view, dose reduction, improved image quality, minimal interference in guided procedures, metal artifact reduction, and more. While modern imaging systems such as robotic C-arms are enabling more freedom in potential orbit designs, practical implementation on such clinical systems remains challenging due to obstacles in critical stages of the workflow, including orbit realization, geometric calibration, and reconstruction. In this work, we build upon previous successes in clinical implementation and address key challenges in the geometric calibration stage with a novel calibration method. The resulting workflow eliminates the need for prior patient scans or dedicated calibration phantoms, and can be conducted in clinically relevant processing times.

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Section: Orbit Design and Implementationmentioning

confidence: 99%

Section: Bench Experiments Implementationmentioning

confidence: 99%

Section: Bench Experiments Implementationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Practical workflow for arbitrary non-circular orbits for CT with clinical robotic C-arms

Yiqun

Gang²,

Reynolds³

et al. 2022

7th International Conference on Image Formation in X-Ray Computed Tomography

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Reduction of cone‐beam CT artifacts in a robotic CBCT device using saddle trajectories with integrated infrared tracking

Wei,

Albrecht,

Rit

et al. 2024

Medical Physics

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BackgroundCone beam computed tomography (CBCT) is widely used in many medical fields. However, conventional CBCT circular scans suffer from cone beam (CB) artifacts that limit the quality and reliability of the reconstructed images due to incomplete data.PurposeSaddle trajectories in theory might be able to improve the CBCT image quality by providing a larger region with complete data. Therefore, we investigated the feasibility and performance of saddle trajectory CBCT scans and compared them to circular trajectory scans.MethodsWe performed circular and saddle trajectory scans using a novel robotic CBCT scanner (Mobile ImagingRing (IRm); medPhoton, Salzburg, Austria). For the saddle trajectory, the gantry executed yaw motion up to using motorized wheels driving on the floor. An infrared (IR) tracking device with reflective markers was used for online geometric calibration correction (mainly floor unevenness). All images were reconstructed using penalized least‐squares minimization with the conjugate gradient algorithm from RTK with voxel size. A disk phantom and an Alderson phantom were scanned to assess the image quality. Results were correlated with the local incompleteness value represented by , which was calculated at each voxel as a function of the source trajectory and the voxel's 3D coordinates. We assessed the magnitude of CB artifacts using the full width half maximum (FWHM) of each disk profile in the axial center of the reconstructed images. Spatial resolution was also quantified by the modulation transfer function at 10% (MTF10).ResultsWhen using the saddle trajectory, the region without CB artifacts was increased from 43 to 190 mm in the SI direction compared to the circular trajectory. This region coincided with low values for . When was larger than 0.02, we found there was a linear relationship between the FWHM and . For the saddle, IR tracking allowed the increase of MTF10 from 0.37 to 0.98 lp/mm.ConclusionsWe achieved saddle trajectory CBCT scans with a novel CBCT system combined with IR tracking. The results show that the saddle trajectory provides a larger region with reliable reconstruction compared to the circular trajectory. The proposed method can be used to evaluate other non‐circular trajectories.

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Fully automatic online geometric calibration for non‐circular cone‐beam CT orbits using fiducials with unknown placement

Ma,

Reynolds,

Ehtiati

et al. 2024

Medical Physics

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BackgroundCone‐beam CT (CBCT) with non‐circular scanning orbits can improve image quality for 3D intraoperative image guidance. However, geometric calibration of such scans can be challenging. Existing methods typically require a prior image, specialized phantoms, presumed repeatable orbits, or long computation time.PurposeWe propose a novel fully automatic online geometric calibration algorithm that does not require prior knowledge of fiducial configuration. The algorithm is fast, accurate, and can accommodate arbitrary scanning orbits and fiducial configurations.MethodsThe algorithm uses an automatic initialization process to eliminate human intervention in fiducial localization and an iterative refinement process to ensure robustness and accuracy. We provide a detailed explanation and implementation of the proposed algorithm. Physical experiments on a lab test bench and a clinical robotic C‐arm scanner were conducted to evaluate spatial resolution performance and robustness under realistic constraints.ResultsQualitative and quantitative results from the physical experiments demonstrate high accuracy, efficiency, and robustness of the proposed method. The spatial resolution performance matched that of our existing benchmark method, which used a 3D‐2D registration‐based geometric calibration algorithm.ConclusionsWe have demonstrated an automatic online geometric calibration method that delivers high spatial resolution and robustness performance. This methodology enables arbitrary scan trajectories and should facilitate translation of such acquisition methods in a clinical setting.

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Non-circular CBCT orbit design and realization on a clinical robotic C-arm for metal artifact reduction

Cited by 8 publications

References 8 publications

Practical workflow for arbitrary non-circular orbits for CT with clinical robotic C-arms

Practical workflow for arbitrary non-circular orbits for CT with clinical robotic C-arms

Reduction of cone‐beam CT artifacts in a robotic CBCT device using saddle trajectories with integrated infrared tracking

Fully automatic online geometric calibration for non‐circular cone‐beam CT orbits using fiducials with unknown placement

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