Prospects for quantitative computed tomography imaging in the presence of foreign metal bodies using statistical image reconstruction

Williamson, Jeffrey F.; Whiting, Bruce R.; Benac, Jasenka; Murphy, Ryan J.; Blaine, G. James; O'Sullivan, Joseph A.; Politte, David G.; Snyder, Donald L.

doi:10.1118/1.1509443

Cited by 86 publications

(93 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is an extension of the method described by Wang, et al [38] for iterative deblurring in the presence of high density attenuators with known attenuation maps. Our results using this approach have been extremely encouraging; see Williamson, et al [41].…”

Section: Discussionmentioning

confidence: 56%

“…We present the results of simulations in this section, demonstrating some key features of the proposed algorithm, namely its ability to account for polyenergetic models and for background events (see also [41]). …”

Section: Simulation Resultsmentioning

confidence: 99%

“…In order to focus on the new algorithm, the images shown below were computed using the full iterations from Subsection 4.1. We have implemented the ordered subset version with promising results [41].…”

Section: Ordered Subsets Alternating Minimization Algorithmsmentioning

confidence: 99%

“…with known linear attenuation coefficients μ i (E) in mm −1 and relative partial densities c i (x) [41]. For pure linear combinations, the relative partial densities are nonnegative and sum to one.…”

Section: Polyenergetic Image Reconstruction Problemmentioning

confidence: 99%

See 3 more Smart Citations

Alternating Minimization Algorithms for Transmission Tomography

O'Sullivan

Benac

2007

IEEE Trans. Med. Imaging

Self Cite

145

153

View full text Add to dashboard Cite

A family of alternating minimization algorithms for finding maximum likelihood estimates of attenuation functions in transmission x-ray tomography is described. The model from which the algorithms are derived includes polyenergetic photon spectra, background events, and nonideal point spread functions. The maximum likelihood image reconstruction problem is reformulated as a double minimization of the I-divergence. A novel application of the convex decomposition lemma results in an alternating minimization algorithm that monotonically decreases the objective function. Each step of the minimization is in closed form. The family of algorithms includes variations that use ordered subset techniques for increasing the speed of convergence. Simulations demonstrate the ability to correct the cupping artifact due to beam hardening and the ability to reduce streaking artifacts that arise from beam hardening and background events.

show abstract

Section: Discussionmentioning

confidence: 56%

Section: Simulation Resultsmentioning

confidence: 99%

Section: Ordered Subsets Alternating Minimization Algorithmsmentioning

confidence: 99%

Section: Polyenergetic Image Reconstruction Problemmentioning

confidence: 99%

See 2 more Smart Citations

Alternating Minimization Algorithms for Transmission Tomography

O'Sullivan

Benac

2007

IEEE Trans. Med. Imaging

Self Cite

145

153

View full text Add to dashboard Cite

show abstract

“…Artifacts in kVCT images from high‐density objects were shown by Williamson et al (13) to be due primarily to mismatches between the simplified model of CT detector response embodied in the filtered backprojection (FBP) reconstruction algorithm and the physical processes of signal acquisition. They demonstrated that their alternating minimization (AM) iterative algorithm performed significantly better than FBP or other iterative algorithms.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of MVCT images with skin collimation for electron beam treatment planning

Beardmore

Rosen

Cheek

et al. 2008

J Applied Clin Med Phys

View full text Add to dashboard Cite

This study assessed the potential of using megavoltage CT (MVCT) images taken with high density skin collimation in place for electron beam treatment planning. MVCT images were taken using the TomoTherapy Hi‐Art system (TomoTherapy Inc., Madison, WI), and the CT numbers were converted to density by calibrating the Hi‐Art system using an electron density phantom. Doses were computed using MVCT images and kVCT images and compared by calculating dose differences in the uniform dose region false(>90%, excluding buildup region) and calculating distance‐to‐agreement (DTA) in high dose‐gradient regions (penumbra and distal falloff, 90%–10%). For 9 and 16 MeV electron beams of 10×10 cm calculated on a homogeneous CIRS Plastic Water (Computerized Imaging Research Systems Inc., Norfolk, VA) phantom without skin collimation, the maximum dose differences were 2.3% and the maximum DTAs were 2.0 mm for both beams. The same phantom was then MVCT scanned nine times with square skin collimators of Cerrobend on its surface ‐ field sizes of 3×3, 6×6, and 10×10 cm and thicknesses of 6, 8, and 10 mm. Using the Philips Pinnacle 3 treatment planning system (Philips Medical Systems, N.A., Bothwell, WA), a treatment plan was created for combinations of electron energies of 6, 9, 12, and 16 MeV and each field size. The same treatment plans were calculated using kVCT images of the phantom with regions‐of‐interest (ROI) manually drawn to duplicate the sizes, shapes, and density of the skin collimators. With few exceptions, the maximum dose differences exceeded ±5% and the DTAs exceeded 2 mm. We determined that the dose differences were due to small distortions in the MVCT images created by the high density material and manifested as errors in the phantom CT numbers and in the shape of the skin collimator edges. These results suggest that MVCT images without skin collimation have potential for use in patient electron beam treatment planning. However, the small distortion in images with skin collimation makes them unsuitable for clinical use.PACS: 87.53.Tf, 87.59.Fm, 87.53.Fs

show abstract

An additional tilted‐scan‐based CT metal‐artifact‐reduction method for radiation therapy planning

Kim

Pua

Lee

et al. 2018

J Applied Clin Med Phys

View full text Add to dashboard Cite

PurposeAs computed tomography (CT) imaging is the most commonly used modality for treatment planning in radiation therapy, metal artifacts in the planning CT images may complicate the target delineation and reduce the dose calculation accuracy. Although current CT scanners do provide certain correction steps, it is a common understanding that there is not a universal solution yet to the metal artifact reduction (MAR) in general. Particularly noting the importance of MAR for radiation treatment planning, we propose a novel MAR method in this work that recruits an additional tilted CT scan and synthesizes nearly metal‐artifact‐free CT images.MethodsThe proposed method is based on the facts that the most pronounced metal artifacts in CT images show up along the x‐ray beam direction traversing multiple metallic objects and that a tilted CT scan can provide complementary information free of such metal artifacts in the earlier scan. Although the tilted CT scan would contain its own metal artifacts in the images, the artifacts may manifest in a different fashion leaving a chance to concatenate the two CT images with the metal artifacts much suppressed. We developed an image processing technique that uses the structural similarity (SSIM) for suppressing the metal artifacts. On top of the additional scan, we proposed to use an existing MAR method for each scan if necessary to further suppress the metal artifacts.ResultsThe proposed method was validated by a simulation study using the pelvic region of an XCAT numerical phantom and also by an experimental study using the head part of the Rando phantom. The proposed method was found to effectively reduce the metal artifacts. Quantitative analyses revealed that the proposed method reduced the mean absolute percentages of the error by up to 86% and 89% in the simulation and experimental studies, respectively.ConclusionsIt was confirmed that the proposed method, using complementary information acquired from an additional tilted CT scan, can provide nearly metal‐artifact‐free images for the treatment planning.

show abstract

Prospects for quantitative computed tomography imaging in the presence of foreign metal bodies using statistical image reconstruction

Cited by 86 publications

References 53 publications

Alternating Minimization Algorithms for Transmission Tomography

Alternating Minimization Algorithms for Transmission Tomography

Evaluation of MVCT images with skin collimation for electron beam treatment planning

An additional tilted‐scan‐based CT metal‐artifact‐reduction method for radiation therapy planning

Contact Info

Product

Resources

About