Metal artifact reduction in cone beam computed tomography using forward projected reconstruction information

Meilinger, Manuel; Schmidgunst, Christian; Schütz, O.; Lang, Elmar

doi:10.1016/j.zemedi.2011.03.002

Cited by 45 publications

(40 citation statements)

References 14 publications

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“…CBCT technology is still being actively researched in the academic arena, with the current areas of interest being low-dose iterative reconstruction, [28][29][30] scatter correction, 31-34 lag correction, [35][36][37][38] and metal artifact reduction. [39][40][41] Conclusion In summary, we suggest that multislice helical CT for the initial diagnostic workup should be the first choice of imaging, whereas CBCT should be assigned for evaluation of the proximate pre-or intraoperative status or for follow-up patients. Nevertheless, since an ultimate conclusion regarding the best imaging tool for the management of temporal bone diseases cannot be made based on cadaver temporal bone imaging alone, the specifications of protocols adequate for clinical otologic CBCT require further study.…”

Section: Discussionmentioning

confidence: 95%

Intraoperative Cone‐Beam Computed Tomography and Multi‐Slice Computed Tomography in Temporal Bone Imaging for Surgical Treatment

Erovic

Chan

Daly

et al. 2013

Otolaryngol.--head neck surg.

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Section: Discussionmentioning

confidence: 95%

Intraoperative Cone‐Beam Computed Tomography and Multi‐Slice Computed Tomography in Temporal Bone Imaging for Surgical Treatment

Erovic

Chan

Daly

et al. 2013

Otolaryngol.--head neck surg.

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“…One procedure involves the segmentation of metal regions in reconstructed images, forwardprojection of those regions to localize the projection data that have been contaminated by the metal implants, replacement of the affected projection data, and reconstruction of the corrected data. 5-8, 23, 26, 27 The maximum a posteriori (MAP) reconstruction combining the iterative reconstruction with projection completion, 23 the fractional-order curvature diffusion-based method, 26 and the forward projected reconstruction-based method 27 utilized this strategy. The advantage of this procedure is that once the metal region is segmented in the reconstructed image, the projection data contaminated by the metal implants can be consistently determined among all projection views through forwardprojection.…”

Section: Introductionmentioning

confidence: 99%

Clinical evaluation of a commercial orthopedic metal artifact reduction tool for CT simulations in radiation therapy

et al. 2012

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Purpose: Severe artifacts in kilovoltage-CT simulation images caused by large metallic implants can significantly degrade the conspicuity and apparent CT Hounsfield number of targets and anatomic structures, jeopardize the confidence of anatomical segmentation, and introduce inaccuracies into the radiation therapy treatment planning process. This study evaluated the performance of the first commercial orthopedic metal artifact reduction function (O-MAR) for radiation therapy, and investigated its clinical applications in treatment planning. Methods: Both phantom and clinical data were used for the evaluation. The CIRS electron density phantom with known physical (and electron) density plugs and removable titanium implants was scanned on a Philips Brilliance Big Bore 16-slice CT simulator. The CT Hounsfield numbers of density plugs on both uncorrected and O-MAR corrected images were compared. Treatment planning accuracy was evaluated by comparing simulated dose distributions computed using the true density images, uncorrected images, and O-MAR corrected images. Ten CT image sets of patients with large hip implants were processed with the O-MAR function and evaluated by two radiation oncologists using a five-point score for overall image quality, anatomical conspicuity, and CT Hounsfield number accuracy. By utilizing the same structure contours delineated from the O-MAR corrected images, clinical IMRT treatment plans for five patients were computed on the uncorrected and O-MAR corrected images, respectively, and compared. Results: Results of the phantom study indicated that CT Hounsfield number accuracy and noise were improved on the O-MAR corrected images, especially for images with bilateral metal implants. The γ pass rates of the simulated dose distributions computed on the uncorrected and O-MAR corrected images referenced to those of the true densities were higher than 99.9% (even when using 1% and 3 mm distance-to-agreement criterion), suggesting that dose distributions were clinically identical. In all patient cases, radiation oncologists rated O-MAR corrected images as higher quality. Formerly obscured critical structures were able to be visualized. The overall image quality and the conspicuity in critical organs were significantly improved compared with the uncorrected images: overall quality score (1.35 vs 3.25, P = 0.0022); bladder (2.15 vs 3.7, P = 0.0023); prostate and seminal vesicles/vagina (1.3 vs 3.275, P = 0.0020); rectum (2.8 vs 3.9, P = 0.0021). The noise levels of the selected ROIs were reduced from 93.7 to 38.2 HU. On most cases (8/10), the average CT Hounsfield numbers of the prostate/vagina on the O-MAR corrected images were closer to the referenced value (41.2 HU, an average measured from patients without metal implants) than those on the uncorrected images. High γ pass rates of the five IMRT dose distribution pairs indicated that the dose distributions were not significantly affected by the CT image improvements. Conclusions: Overall, this study indicated that the O-MAR function can remark...

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“…Besides, metal objects such as metal implants, dental fillings, and prostheses possess high densities, therefore the presence of high-density objects in field of view (FOV) can lead to the severe metal artifacts which seriously degrade image diagnosis value 19–21 . Generally, noise, exponential edge gradient effect, beam hardening artifacts, and scatter artifacts are all the causes of metal artifacts 19 .…”

Section: Introductionmentioning

confidence: 99%

John’s Equation-based Consistency Condition and Corrupted Projection Restoration in Circular Trajectory Cone Beam CT

et al. 2017

Sci Rep

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In transmitted X-ray tomography imaging, the acquired projections may be corrupted for various reasons, such as defective detector cells and beam-stop array scatter correction problems. In this study, we derive a consistency condition for cone-beam projections and propose a method to restore lost data in corrupted projections. In particular, the relationship of the geometry parameters in circular trajectory cone-beam computed tomography (CBCT) is utilized to convert an ultra-hyperbolic partial differential equation (PDE) into a second-order PDE. The second-order PDE is then transformed into a first-order ordinary differential equation in the frequency domain. The left side of the equation for the newly derived consistency condition is the projection derivative of the current and adjacent views, whereas the right side is the projection derivative of the geometry parameters. A projection restoration method is established based on the newly derived equation to restore corrupted data in projections in circular trajectory CBCT. The proposed method is tested in beam-stop array scatter correction, metal artifact reduction, and abnormal pixel correction cases to evaluate the performance of the consistency condition and corrupted projection restoration method. Qualitative and quantitative results demonstrate that the present method has considerable potential in restoring lost data in corrupted projections.

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Metal artifact reduction in cone beam computed tomography using forward projected reconstruction information

Cited by 45 publications

References 14 publications

Intraoperative Cone‐Beam Computed Tomography and Multi‐Slice Computed Tomography in Temporal Bone Imaging for Surgical Treatment

Intraoperative Cone‐Beam Computed Tomography and Multi‐Slice Computed Tomography in Temporal Bone Imaging for Surgical Treatment

Clinical evaluation of a commercial orthopedic metal artifact reduction tool for CT simulations in radiation therapy

John’s Equation-based Consistency Condition and Corrupted Projection Restoration in Circular Trajectory Cone Beam CT

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