Improvements to image quality using hybrid and model-based iterative reconstructions: a phantom study

Aurumskjöld, Marie-Louise; Ydström, Kristina; Tingberg, Anders; Söderberg, Marcus

doi:10.1177/0284185116631180

Cited by 19 publications

(14 citation statements)

References 15 publications

(36 reference statements)

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“…Noise and uniformity within all image acquisition protocols also conformed to the requirements of the American College of Radiology [15]. In agreement with a previous study utilizing a Catphan image quality phantom [22], image quality assessment demonstrated that CT numbers were not affected by IR settings.…”

Section: Discussionsupporting

confidence: 87%

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The Acceptability of Iterative Reconstruction Algorithms in Head CT: An Assessment of Sinogram Affirmed Iterative Reconstruction (SAFIRE) vs. Filtered Back Projection (FBP) Using Phantoms

Harris

Huckle

Anthony

et al. 2017

Journal of Medical Imaging and Radiation Sciences

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Background: Computed tomography (CT) is the primary imaging investigation for many neurologic conditions with a proportion of patients incurring cumulative doses. Iterative reconstruction (IR) allows dose optimization, but head CT presents unique image quality complexities and may lead to strong reader preferences. Objectives: This study evaluates the relationships between image quality metrics, image texture, and applied radiation dose within the context of IR head CT protocol optimization in the simulated patient setting. A secondary objective was to determine the influence of optimized protocols on diagnostic confidence using a custom phantom. Methods and Setting: A three-phase phantom study was performed to characterize reconstruction methods at the local reference standard and a range of exposures. CT numbers and pixel noise were quantified supplemented by noise uniformity, noise power spectrum, contrast-to-noise ratio (CNR), high-and low-contrast resolution. Reviewers scored optimized protocol images based on established reporting criteria. Results: Increasing strengths of IR resulted in lower pixel noise, lower noise variance, and increased CNR. At the reference standard, the image noise was reduced by 1.5 standard deviation and CNR increased by 2.0. Image quality was maintained at 24% relative dose reduction. With the exception of image sharpness, there were no significant differences between grading for IR and filtered back projection reconstructions. Conclusions: IR has the potential to influence pixel noise, CNR, and noise variance (image texture); however, systematically optimized IR protocols can maintain the image quality of filtered back projection. This work has guided local application and acceptance of lower dose head CT protocols.

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Section: Discussionsupporting

confidence: 87%

“…However, other institutions prefer to practice on the side of caution and report only 15% dose reduction for CT head [25]. With the combination of novel dose-reducing strategies such as model-based reconstruction methods [22,26] and noise efficient detectors [27], there is likely to be further significant dose reduction in the future.…”

Section: Discussionmentioning

confidence: 99%

The Acceptability of Iterative Reconstruction Algorithms in Head CT: An Assessment of Sinogram Affirmed Iterative Reconstruction (SAFIRE) vs. Filtered Back Projection (FBP) Using Phantoms

Harris

Huckle

Anthony

et al. 2017

Journal of Medical Imaging and Radiation Sciences

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“…[8][9][10][11] Phantoms have been widely applied in medical imaging, especially in CT systems, commonly for both quantitative and qualitative assessments of image quality. Many prior studies [12][13][14] have highlighted the advantages of using phantoms, especially when the investigations involve multiple radiation exposures with different acquisitions settings. One of the most common phantoms used for the investigations of CT protocols is the anthropomorphic chest phantom (Kyoto Kagaku, Japan).…”

Section: Introductionmentioning

confidence: 99%

Development of an organ‐specific insert phantom generated using a 3D printer for investigations of cardiac computed tomography protocols

Abdullah

McEntee

Reed

et al. 2018

J of Medical Radiation Sci

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IntroductionAn ideal organ‐specific insert phantom should be able to simulate the anatomical features with appropriate appearances in the resultant computed tomography (CT) images. This study investigated a 3D printing technology to develop a novel and cost‐effective cardiac insert phantom derived from volumetric CT image datasets of anthropomorphic chest phantom.MethodsCardiac insert volumes were segmented from CT image datasets, derived from an anthropomorphic chest phantom of Lungman N‐01 (Kyoto Kagaku, Japan). These segmented datasets were converted to a virtual 3D‐isosurface of heart‐shaped shell, while two other removable inserts were included using computer‐aided design (CAD) software program. This newly designed cardiac insert phantom was later printed by using a fused deposition modelling (FDM) process via a Creatbot DM Plus 3D printer. Then, several selected filling materials, such as contrast media, oil, water and jelly, were loaded into designated spaces in the 3D‐printed phantom. The 3D‐printed cardiac insert phantom was positioned within the anthropomorphic chest phantom and 30 repeated CT acquisitions performed using a multi‐detector scanner at 120‐kVp tube potential. Attenuation (Hounsfield Unit, HU) values were measured and compared to the image datasets of real‐patient and Catphan® 500 phantom.ResultsThe output of the 3D‐printed cardiac insert phantom was a solid acrylic plastic material, which was strong, light in weight and cost‐effective. HU values of the filling materials were comparable to the image datasets of real‐patient and Catphan® 500 phantom.ConclusionsA novel and cost‐effective cardiac insert phantom for anthropomorphic chest phantom was developed using volumetric CT image datasets with a 3D printer. Hence, this suggested the printing methodology could be applied to generate other phantoms for CT imaging studies.

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“…Imaging phantoms are widely used as a tool for assessing the performance of IR algorithms for dose reduction in CCTA scans. Many phantoms, such as the Catphan â (The Phantom Laboratory, Salem, NY) phantom, used in the previous studies [9][10][11] to provide a good first-order approximation of image quality. However, it is possible that such phantoms are not fully adequate to assess the impact of IR algorithms due to their current shape, the complexity of IR algorithms and the different types of patient body habitus, which can influence the radiation dose during CCTA scans.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of an integrated 3D‐printed phantom for coronary CT angiography using iterative reconstruction algorithm

Abdullah

McEntee

Reed

et al. 2020

J of Medical Radiation Sci

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Introduction 3D‐printed imaging phantoms are now increasingly available and used for computed tomography (CT) dose optimisation study and image quality analysis. The aim of this study was to evaluate the integrated 3D‐printed cardiac insert phantom when evaluating iterative reconstruction (IR) algorithm in coronary CT angiography (CCTA) protocols. Methods The 3D‐printed cardiac insert phantom was positioned into a chest phantom and scanned with a 16‐slice CT scanner. Acquisitions were performed with CCTA protocols using 120 kVp at four different tube currents, 300, 200, 100 and 50 mA (protocols A, B, C and D, respectively). The image data sets were reconstructed with a filtered back projection (FBP) and three different IR algorithm strengths. The image quality metrics of image noise, signal–noise ratio (SNR) and contrast–noise ratio (CNR) were calculated for each protocol. Results Decrease in dose levels has significantly increased the image noise, compared to FBP of protocol A (P < 0.001). As a result, the SNR and CNR were significantly decreased (P < 0.001). For FBP, the highest noise with poor SNR and CNR was protocol D with 19.0 ± 1.6 HU, 18.9 ± 2.5 and 25.1 ± 3.6, respectively. For IR algorithm, the highest strength (AIDR3Dstrong) yielded the lowest noise with excellent SNR and CNR. Conclusions The use of IR algorithm and increasing its strengths have reduced noise significantly and thus increased the SNR and CNR when compared to FBP. Therefore, this integrated 3D‐printed phantom approach could be used for dose optimisation study and image quality analysis in CCTA protocols.

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Improvements to image quality using hybrid and model-based iterative reconstructions: a phantom study

Abstract: There is great potential to reduce noise and thereby improve image quality by using hybrid or, in particular, model-based iterative reconstruction methods, or to lower radiation dose and maintain image quality.

Cited by 19 publications

References 15 publications

The Acceptability of Iterative Reconstruction Algorithms in Head CT: An Assessment of Sinogram Affirmed Iterative Reconstruction (SAFIRE) vs. Filtered Back Projection (FBP) Using Phantoms

The Acceptability of Iterative Reconstruction Algorithms in Head CT: An Assessment of Sinogram Affirmed Iterative Reconstruction (SAFIRE) vs. Filtered Back Projection (FBP) Using Phantoms

Development of an organ‐specific insert phantom generated using a 3D printer for investigations of cardiac computed tomography protocols

Evaluation of an integrated 3D‐printed phantom for coronary CT angiography using iterative reconstruction algorithm

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