Reducing metal artifacts in cone-beam CT images by preprocessing projection data

Zhang, Yongbin; Zhang, Lifei; Zhu, Xiangxin; Lee, Andrew K.; Chambers, Mark S.; Dong, Lei

doi:10.1016/j.ijrobp.2006.09.045

Cited by 190 publications

(151 citation statements)

References 30 publications

Supporting

Mentioning

144

Contrasting

Unclassified

Order By: Relevance

“…26 Related studies show a high correlation between image quality, accuracy of linear measurement and image artefacts. Future studies have to evaluate the further development of image artefact-reducing algorithms and the approval of beam-hardening artefacts in CBCT.…”

Section: Discussionmentioning

confidence: 98%

Accuracy of peri-implant bone evaluation using cone beam CT, digital intra-oral radiographs and histology

Ritter

Elger²,

Rothamel³

et al. 2014

Dentomaxillofacial Radiology

104

121

View full text Add to dashboard Cite

Objectives: The present study assesses the accuracy of three-dimensional (3D) cone beam CT (CBCT) and intra-oral radiography (CR) in visualizing peri-implant bone compared with histology. Methods: 26 titanium dental implants were placed in dog jaws with chronic type vestibular defects. After a healing period of 2 and 8 weeks (n 5 12 dogs) the animals were sacrificed. CBCT scans and CR of the specimen were recorded. Dissected blocks were prepared, and histomorphometric analysis was performed. Both modalities were measured twice by two observers and compared with histomorphometry regarding bone levels and thickness around implants as well as length and diameter of implants. Results: Measurements of CBCT correlated well with histomorphometry of the vestibular bone level, oral bone thickness and implant length (all p-values ,0.05). Compared with histomorphometry, the mean differences between CBCT and histomorphometry were between 0.06 and 2.61 mm. Mesial bone level (MBL) and distal bone level (DBL) were underestimated by both CR and CBCT. CR and histology measurements were only significantly correlated for implant length measurements. All intraclass correlations were highly significant. Conclusions: 3D CBCT provides usable information about bone in all dimensions around implants with varying accuracy. CR and CBCT perform similar in assessing MBL and DBL, but, within its limits, the CBCT can assess oral and buccal bone. Metallic artefacts limit the visualization quality of bone around implants and further research could elucidate the value of post-processing algorithms. When information about osseous perforation of implants is needed, CBCT may still provide clinically valuable information.

show abstract

Section: Discussionmentioning

confidence: 98%

Accuracy of peri-implant bone evaluation using cone beam CT, digital intra-oral radiographs and histology

Ritter

Elger²,

Rothamel³

et al. 2014

Dentomaxillofacial Radiology

104

121

View full text Add to dashboard Cite

show abstract

“…The metal artifacts caused by gold markers may be reduced using proposed metal artifact reduction algorithms for helical CT 22 or using the image registration technique between helical CT image and cone beam CT image with metal artifact removed 23 . The proton range precision with these metal-artifact-free CTs should be investigated in future.…”

Section: Discussionmentioning

confidence: 99%

Biological effect of dose distortion by fiducial markers in spot‐scanning proton therapy with a limited number of fields: A simulation study

et al. 2012

View full text Add to dashboard Cite

Purpose: In accurate proton spot-scanning therapy, continuous target tracking by fluoroscopic X-ray during irradiation is beneficial not only for respiratory moving tumors of lung and liver but also for relatively stationary tumors of prostate. Implanted gold markers have been used with great effect for positioning the target volume by a fluoroscopy, especially for the cases of liver and prostate with the targets surrounded by water-equivalent tissues.However, recent studies have revealed that gold markers can cause a significant underdose in proton therapy. This paper focuses on prostate cancer and explores the possibility that multiple-field irradiation improves the underdose effect by markers on Tumor Control Probability (TCP). Methods:A Monte Carlo simulation was performed to evaluate the dose distortion effect. A spherical gold marker was placed at several characteristic points in a water phantom. Markers were with two different diameters of 2 mm and 1.5 mm, both visible on fluoroscopy. Three beam arrangements of SFUD (single-field uniform dose)were examined: one lateral field, two opposite lateral fields, and three fields (two opposite lateral fields + anterior field). The Relative Biological Effectiveness (RBE) was set to 1.1 and a dose of 74 Gy (RBE) was delivered to the target of a typical prostate size in 37 fractions. The ratios of TCP to that without the marker (TCP r ) were compared with the parameters of the marker sizes, number of fields, and marker positions. To take into account the dependence of biological parameters in TCP model,  values of 1.5, 3, and 10 Gy (RBE) were considered.Results: It was found that the marker of 1.5 mm diameter does not affect the TCPs with all  values when two or more fields are used. On the other hand, if the marker size is 2 mm, more than two irradiation fields are required to suppress the decrease in TCP from TCP r by less than 3%. This is especially true when multiple (two or three) markers are used for alignment of a patient. Conclusions:It is recommended that 1.5 mm markers be used to avoid the reduction of TCP as well as to spare the surrounding critical organs, as long as the markers are visible on X-ray fluoroscopy. When 2 mm markers are implanted, more than two fields should be used and the markers should not be placed close to the distal edge of any of the beams.

show abstract

“…7 All these factors in the measurement and reconstruction process introduce artefacts into the cone beam datasets. 12,29,30 The technique to determine the MTFs for CT or CBCT scanners resembles the technique used for X-ray detectors. Initially, a measurement must be performed to obtain either the point spread function or the LSF.…”

Section: Resolution Of the Two-dimensional Detectormentioning

confidence: 99%

Spatial resolution in CBCT machines for dental/maxillofacial applications—what do we know today?

Brüllmann

Schulze²

2015

Dentomaxillofacial Radiology

152

126

View full text Add to dashboard Cite

Spatial resolution is one of the most important parameters objectively defining image quality, particularly in dental imaging, where fine details often have to be depicted. Here, we review the current status on assessment parameters for spatial resolution and on published data regarding spatial resolution in CBCT images. The current concepts of visual [line-pair (lp) measurements] and automated [modulation transfer function (MTF)] assessment of spatial resolution in CBCT images are summarized and reviewed. Published measurement data on spatial resolution in CBCT are evaluated and analysed. Effective (i.e. actual) spatial resolution available in CBCT images is being influenced by the two-dimensional detector, the threedimensional reconstruction process, patient movement during the scan and various other parameters. In the literature, the values range between 0.6 and 2.8 lp mm 21 (visual assessment; median, 1.7 lp mm ). Spatial resolution of CBCT images is approximately one order of magnitude lower than that of intraoral radiographs. Considering movement, scatter effects and other influences in real-world scans of living patients, a realistic spatial resolution of just above 1 lp mm 21 could be expected.

show abstract

Reducing metal artifacts in cone-beam CT images by preprocessing projection data

Cited by 190 publications

References 30 publications

Accuracy of peri-implant bone evaluation using cone beam CT, digital intra-oral radiographs and histology

Accuracy of peri-implant bone evaluation using cone beam CT, digital intra-oral radiographs and histology

Biological effect of dose distortion by fiducial markers in spot‐scanning proton therapy with a limited number of fields: A simulation study

Spatial resolution in CBCT machines for dental/maxillofacial applications—what do we know today?

Contact Info

Product

Resources

About