Initial Assessment of a Prototype 3D Cone-Beam Computed Tomography System for Imaging of the Lumbar Spine, Evaluating Human Cadaveric Specimens in the Upright Position

Benz, Robyn Melanie; Harder, Dorothee; Amsler, Felix; Voigt, Johannes M.; Fieselmann, Andreas; Falkowski, Anna L.; Stieltjes, Bram; Hirschmann, Anna

doi:10.1097/rli.0000000000000495

Cited by 18 publications

(13 citation statements)

References 27 publications

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“…Since dedicated extremity scanners became commercially available during the last decade, CBCT is also increasingly used in musculoskeletal imaging. While current literature is mainly focused on weight-bearing scans of spine (10), knee (11), and ankle (12À14) in upright position, patients with upper extremity injuries can also benefit from the upsides of the cone-beam technology (15À18).…”

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confidence: 99%

Evaluation of Ultra-High-Resolution Cone-Beam CT Prototype of Twin Robotic Radiography System for Cadaveric Wrist Imaging

et al. 2021

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Rationale and Objectives: Cone-beam CT (CBCT) applications possess potential for dose reduction in musculoskeletal imaging. This study evaluates the ultra-high-resolution CBCT prototype of a twin robotic X-ray system in wrist examinations compared to high-resolution multidetector CT (MDCT).Materials and Methods: Sixteen wrists of body donors were examined with the CBCT scan mode and a 384 slice MDCT system. Radiation-equivalent low-dose (CTDI vol(16cm) = 3.3 mGy) and full-dose protocols (CTDI vol(16cm) = 13.8 mGy) were used for both systems. Two observers assessed image quality on a seven-point Likert scale. In addition, software-assisted quantification of signal intensity fractions in cancellous bone was performed. Fewer pixels with intermediate signal intensity were considered to indicate superior depiction of bone microarchitecture.Results: Subjective image quality in CBCT was superior to dose equivalent MDCT with p 0.03 for full-dose and p < 0.001 for low-dose scans, respectively. Median Likert values were 7/7 (reader 1 / reader 2) in full-dose CBCT, 6/6 in full-dose MDCT, 5/6 in low-dose CBCT and 3/3 in low-dose MDCT. Intraclass correlation coefficient was 0.936 (95% confidence interval, 0.897-0.961; p < 0.001), indicating excellent reliability. Objective analysis displayed smaller fractions of "indecisive" pixels with intermediate signal intensity for full-dose CBCT (0.57 [interquartile range 0.13]) compared to full-dose MDCT (0.68 [0.21]), low-dose CBCT (0.72 [0.19]), and low-dose MDCT (0.80 [0.15]) studies. No significant difference was observed between low-dose CBCT and full-dose MDCT. Conclusion:The new CBCT prototype provides superior image quality for trabecula and bone marrow in cadaveric wrist studies and enables dose reduction up to 75% compared to high-resolution MDCT.

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confidence: 99%

Evaluation of Ultra-High-Resolution Cone-Beam CT Prototype of Twin Robotic Radiography System for Cadaveric Wrist Imaging

et al. 2021

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“…A high-fidelity 3D CBCT simulation framework described in detail and validated in Refs. [24,25] was used to assess the image quality in the proposed tilted axis CBCT acquisitions.…”

Section: C1 Cbct Simulation Frameworkmentioning

confidence: 99%

“…In Refs. [24,25], the simulation framework was validated for simple horizontal CBCT orbits and shown to yield accurate estimates of projection noise power spectra (NPS) and of scatter-induced cupping in 3D reconstructions (simulated cupping of 13.8% compared to measured value of 14.6%).…”

Section: C2 Validation Of the Cbct Simulation Frameworkmentioning

confidence: 99%

Cone‐beam imaging with tilted rotation axis: Method and performance evaluation

et al. 2020

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The recently introduced robotic x-ray systems provide the flexibility to acquire cone-beam computed tomography (CBCT) data using customized, application-specific source-detector trajectories. We exploit this capability to mitigate the effects of x-ray scatter and noise in CBCT imaging of weight-bearing foot and cervical spine (C-spine) using scan orbits with a tilted rotation axis. Methods: We used an advanced CBCT simulator implementing accurate models of x-ray scatter, primary attenuation, and noise to investigate the effects of the orbital tilt angle in upright foot and Cspine imaging. The system model was parameterized using a laboratory version of a three-dimensional (3D) robotic x-ray system (Multitom RAX, Siemens Healthineers). We considered a generalized tilted axis scan configuration, where the detector remained parallel to patient's long body axis during the acquisition, but the elevation of source and detector was changing. A modified Feldkamp-Davis-Kress (FDK) algorithm was developed for reconstruction in this configuration, which departs from the FDK assumption of a detector that is perpendicular to the scan plane. The simulated foot scans involved source-detector distance (SDD) of 1386 mm, orbital tilt angles ranging 10°to 40°, and 400 views at 1 mAs/view and 0.5°increment; the C-spine scans involved À25°to À45°tilt angles, SDD of 1090 mm, and 202 views at 1.3 mAs and 1°increment The imaging performance was assessed by projection-domain measurements of the scatter-to-primary ratio (SPR) and by reconstruction-domain measurements of contrast, noise and generalized contrast-to-noise ratio (gCNR, accounting for both image noise and background nonuniformity) of the metatarsals (foot imaging) and cervical vertebrae (spine imaging). The effects of scatter correction were also compared for horizontal and tilted scans using an ideal Monte Carlo (MC)-based scatter correction and a frame-byframe mean scatter correction. Results: The proposed modified FDK, involving projection resampling, mitigated streak artifacts caused by the misalignment between the filtering direction and the detector rows. For foot imaging (no grids), an optimized 20°tilted orbit reduced the maximum SPR from~1.5 in a horizontal scan to <0.5. The gCNR of the second metatarsal was enhanced twofold compared to a horizontal orbit. For the C-spine (with vertical grids), imaging with a tilted orbit avoided highly attenuating x-ray paths through the lower cervical vertebrae and shoulders. A À35°tilted orbit yielded improved image quality and visualization of the lower cervical spine: the SPR of lower cervical vertebrae was reduced from~10 (horizontal orbit) to <6 (tilted orbit), and the gCNR for C5-C7 increased by a factor of 2. Furthermore, tilted orbits showed potential benefits over horizontal orbits by enabling scatter correction with a simple frame-by-frame mean correction without substantial increase in noise-induced artifacts after the correction. Conclusions: Tilted scan trajectories, enabled by the emerging robotic x-ray system technolo...

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“…CTDI vol was calculated after a modified (to account for geometric inequality) scanning of a 16 cm standard head phantom (data not shown, see [22]). CTDI vol was calculated following the IEC (International Electrotechnical Commission) 60601-2-44 A1 standard method [23].…”

Section: Estimation Of Radiation Exposurementioning

confidence: 99%

Cone Beam CT Imaging of the Paranasal Region with a Multipurpose X-ray System—Image Quality and Radiation Exposure

et al. 2020

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Besides X-ray and fluoroscopy, a previously introduced X-ray scanner offers a 3D cone beam option (Multitom Rax, Siemens Healthcare). The aim of this study was to evaluate various scan parameters and post-processing steps to optimize image quality and radiation exposure for imaging of the parasinus region. Four human cadaver heads were examined with different tube voltages (90–121 kV), dose levels (DLs) (278–2180 nGy) and pre-filtration methods (none, Cu 0.2 mm, Cu 0.3 mm and Sn 0.4 mm). All images were reconstructed in 2 mm slice thickness with and without a metal artifact reduction algorithm in three different kernels. In total, 80 different scan protocols and 480 datasets were evaluated. Image quality was rated on a 5-point Likert scale. Radiation exposure (mean computed tomography volume index (CTDIvol) and effective dose) was calculated for each scan. The most dose-effective combination for the diagnosis of sinusitis was 121 kV/DL of 278/0.3 mm copper (CTDIvol 1.70 mGy, effective dose 77 µSv). Scan protocols with 121 kV/DL1090/0.3 mm copper were rated sufficient for preoperative sinus surgery planning (CTDIvol 4.66 mGy, effective dose 212 µSv). Therefore, sinusitis and preoperative sinus surgery planning can be performed in diagnostic image quality at low radiation dose levels with a multipurpose X-ray system.

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Initial Assessment of a Prototype 3D Cone-Beam Computed Tomography System for Imaging of the Lumbar Spine, Evaluating Human Cadaveric Specimens in the Upright Position

Cited by 18 publications

References 27 publications

Evaluation of Ultra-High-Resolution Cone-Beam CT Prototype of Twin Robotic Radiography System for Cadaveric Wrist Imaging

Evaluation of Ultra-High-Resolution Cone-Beam CT Prototype of Twin Robotic Radiography System for Cadaveric Wrist Imaging

Cone‐beam imaging with tilted rotation axis: Method and performance evaluation

Cone Beam CT Imaging of the Paranasal Region with a Multipurpose X-ray System—Image Quality and Radiation Exposure

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