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Larsen T, Tseng HW, Trinate R, Fu Z, Alan Chiang JT, Karellas A, Vedantham S. Maximizing microcalcification detectability in low-dose dedicated cone-beam breast CT: parallel cascades-based theoretical analysis. J Med Imaging (Bellingham) 2024; 11:033501. [PMID: 38756437 PMCID: PMC11095120 DOI: 10.1117/1.jmi.11.3.033501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 04/22/2024] [Accepted: 04/29/2024] [Indexed: 05/18/2024] Open
Abstract
Purpose We aim to determine the combination of X-ray spectrum and detector scintillator thickness that maximizes the detectability of microcalcification clusters in dedicated cone-beam breast CT. Approach A cascaded linear system analysis was implemented in the spatial frequency domain and was used to determine the detectability index using numerical observers for the imaging task of detecting a microcalcification cluster with 0.17 mm diameter calcium carbonate spheres. The analysis considered a thallium-doped cesium iodide scintillator coupled to a complementary metal-oxide semiconductor detector and an analytical filtered-back-projection reconstruction algorithm. Independent system parameters considered were the scintillator thickness, applied X-ray tube voltage, and X-ray beam filtration. The combination of these parameters that maximized the detectability index was considered optimal. Results Prewhitening, nonprewhitening, and nonprewhitening with eye filter numerical observers indicate that the combination of 0.525 to 0.6 mm thick scintillator, 70 kV, and 0.25 to 0.4 mm added copper filtration maximized the detectability index at a mean glandular dose (MGD) of 4.5 mGy. Conclusion Using parallel cascade systems' analysis, the combination of parameters that could maximize the detection of microcalcifications was identified. The analysis indicates that a harder beam than that used in current practice may be beneficial for the task of detecting microcalcifications at an MGD suitable for breast cancer screening.
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Affiliation(s)
- Thomas Larsen
- University of Arizona, Department of Biomedical Engineering, Tucson, Arizona, United States
| | - Hsin Wu Tseng
- University of Arizona, Department of Medical Imaging, Tucson, Arizona, United States
| | - Rachawadee Trinate
- University of Arizona, Department of Biomedical Engineering, Tucson, Arizona, United States
| | - Zhiyang Fu
- University of Arizona, Department of Medical Imaging, Tucson, Arizona, United States
| | - Jing-Tzyh Alan Chiang
- University of Arizona, Department of Medical Imaging, Tucson, Arizona, United States
| | - Andrew Karellas
- University of Arizona, Department of Medical Imaging, Tucson, Arizona, United States
| | - Srinivasan Vedantham
- University of Arizona, Department of Biomedical Engineering, Tucson, Arizona, United States
- University of Arizona, Department of Medical Imaging, Tucson, Arizona, United States
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Vedantham S. Contrast-enhanced breast computed tomography: can lymph node metastasis be predicted from primary tumor? Eur Radiol 2024; 34:2574-2575. [PMID: 37930415 DOI: 10.1007/s00330-023-10399-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 09/29/2023] [Accepted: 10/14/2023] [Indexed: 11/07/2023]
Affiliation(s)
- Srinivasan Vedantham
- Department of Medical Imaging, The University of Arizona, 1501 N Campbell Avenue, Tucson, AZ, 85724, USA.
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Brahimetaj R, Cornelis J, Van Ongeval C, De Mey J, Jansen B. The impact of (simulated) resolution on breast cancer diagnosis based on high-resolution 3D micro-CT microcalcification images. Med Phys 2024; 51:1754-1762. [PMID: 37698346 DOI: 10.1002/mp.16708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 08/09/2023] [Accepted: 08/23/2023] [Indexed: 09/13/2023] Open
Abstract
BACKGROUND Breast microcalcifications (MCs) are considered to be a robust marker of breast cancer. A machine learning model can provide breast cancer diagnosis based on properties of individual MCs - if their characteristics are captured at high resolution and in 3D. PURPOSE The main purpose of the study was to explore the impact of image resolution (8 µm, 16 µm, 32 µm, 64 µm) when diagnosing breast cancer using radiomics features extracted from individual high resolution 3D micro-CT MC images. METHODS Breast MCs extracted from 86 female patients were analyzed at four different spatial resolutions: 8 µm (original resolution) and 16 µm, 32 µm, 64 µm (simulated image resolutions). Radiomic features were extracted at each image resolution in an attempt, to find a compact feature signature allowing to distinguish benign and malignant MCs. Machine learning algorithms were used for classifying individual MCs and samples (i.e., patients). For sample diagnosis, a custom-based thresholding approach was used to combine individual MC results into sample results. We conducted classification experiments when using (a) the same MCs visible in 8 µm, 16 µm, 32 µm, and 64 µm resolution; (b) the same MCs visible in 8 µm, 16 µm, and 32 µm resolution; (c) the same MCs visible in 8 µm and 16 µm resolution; (d) all MCs visible in 8 µm, 16 µm, 32 µm, and 64 µm resolution. Accuracy, sensitivity, specificity, AUC, and F1 score were computed for each experiment. RESULTS The individual MC results yielded an accuracy of 77.27%, AUC of 83.83%, F1 score of 77.25%, sensitivity of 80.86%, and specificity of 72.2% at 8 µm resolution. For the individual MC classifications we report for the F1 scores: a 2.29% drop when using 16 µm instead of 8 µm, a 4.01% drop when using 32 µm instead of 8 µm, a 10.69% drop when using 64 µm instead of 8 µm. The sample results yielded an accuracy and F1 score of 81.4%, sensitivity of 80.43%, and specificity value of 82.5% at 8 µm. For the sample classifications we report for F1 score values: a 6.3% drop when using 16 µm instead of 8 µm, a 4.91% drop when using 32 µm instead of 8 µm, and a 6.3% drop when using 64 µm instead of 8 µm. CONCLUSIONS The highest classification results are obtained at the highest resolution (8 µm). If breast MCs characteristics could be visualized/captured in 3D at a higher resolution compared to what is used nowadays in digital mammograms (approximately 70 µm), breast cancer diagnosis will be improved.
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Affiliation(s)
- Redona Brahimetaj
- Department of Electronics and Informatics (ETRO), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Jan Cornelis
- Department of Electronics and Informatics (ETRO), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Chantal Van Ongeval
- Department of Radiology, Universitair Ziekenhuis Leuven, KU Leuven, Leuven, Belgium
| | - Johan De Mey
- Department of Radiology, Universitair Ziekenhuis Brussel, Brussels, Belgium
| | - Bart Jansen
- Department of Electronics and Informatics (ETRO), Vrije Universiteit Brussel (VUB), Brussels, Belgium
- IMEC, Leuven, Belgium
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Mettivier G, Lai Y, Jia X, Russo P. Virtual dosimetry study with three cone-beam breast computed tomography scanners using a fast GPU-based Monte Carlo code. Phys Med Biol 2024; 69:045028. [PMID: 38237186 DOI: 10.1088/1361-6560/ad2012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 01/18/2024] [Indexed: 02/15/2024]
Abstract
Objective. To compare the dosimetric performance of three cone-beam breast computed tomography (BCT) scanners, using real-time Monte Carlo-based dose estimates obtained with the virtual clinical trials (VCT)-BREAST graphical processing unit (GPU)-accelerated platform dedicated to VCT in breast imaging. Approach. A GPU-based Monte Carlo (MC) code was developed for replicatingin silicothe geometric, x-ray spectra and detector setups adopted, respectively, in two research scanners and one commercial BCT scanner, adopting 80 kV, 60 kV and 49 kV tube voltage, respectively. Our cohort of virtual breasts included 16 anthropomorphic voxelized breast phantoms from a publicly available dataset. For each virtual patient, we simulated exams on the three scanners, up to a nominal simulated mean glandular dose of 5 mGy (primary photons launched, in the order of 1011-1012per scan). Simulated 3D dose maps (recorded for skin, adipose and glandular tissues) were compared for the same phantom, on the three scanners. MC simulations were implemented on a single NVIDIA GeForce RTX 3090 graphics card.Main results.Using the spread of the dose distribution as a figure of merit, we showed that, in the investigated phantoms, the glandular dose is more uniform within less dense breasts, and it is more uniformly distributed for scans at 80 kV and 60 kV, than at 49 kV. A realistic virtual study of each breast phantom was completed in about 3.0 h with less than 1% statistical uncertainty, with 109primary photons processed in 3.6 s computing time.Significance. We reported the first dosimetric study of the VCT-BREAST platform, a fast MC simulation tool for real-time virtual dosimetry and imaging trials in BCT, investigating the dose delivery performance of three clinical BCT scanners. This tool can be adopted to investigate also the effects on the 3D dose distribution produced by changes in the geometrical and spectrum characteristics of a cone-beam BCT scanner.
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Affiliation(s)
- Giovanni Mettivier
- Dipartimento di Fisica 'Ettore Pancini', Università di Napoli Federico II, I-80126 Naples, Italy
- INFN Sezione di Napoli, I-80126 Naples, Italy
| | - Youfang Lai
- Innovative Technology of Radiotherapy Computation and Hardware (iTORCH) Laboratory, Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 752878, United States of America
| | - Xun Jia
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, Baltimore, MD 21224, United States of America
| | - Paolo Russo
- Dipartimento di Fisica 'Ettore Pancini', Università di Napoli Federico II, I-80126 Naples, Italy
- INFN Sezione di Napoli, I-80126 Naples, Italy
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Lyu SH, Abbey CK, Hernandez AM, Boone JM. Microcalcification detectability in breast CT images using CNN observers. Med Phys 2024; 51:933-945. [PMID: 38154070 PMCID: PMC10922367 DOI: 10.1002/mp.16922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/16/2023] [Accepted: 12/16/2023] [Indexed: 12/30/2023] Open
Abstract
BACKGROUND Breast computed tomography (CT) is an emerging breast imaging modality, and ongoing developments aim to improve breast CT's ability to detect microcalcifications. To understand the effects of different parameters on microcalcification detectability, a virtual clinical trial study was conducted using hybrid images and convolutional neural network (CNN)-based model observers. Mathematically generated microcalcifications were embedded into breast CT data sets acquired at our institution, and parameters related to calcification size, calcification contrast, cluster diameter, cluster density, and image display method (i.e., single slices, slice averaging, and maximum-intensity projections) were evaluated for their influence on microcalcification detectability. PURPOSE To investigate the individual effects and the interplay of parameters affecting microcalcification detectability in breast CT. METHODS Spherical microcalcifications of varying diameters (0.04, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40 mm) and native intensities were computer simulated to portray the partial volume effects of the imaging system. Calcifications were mathematically embedded into 109 patient breast CT volume data sets as individual calcifications or as clusters of calcifications. Six numbers of calcifications (1, 3, 5, 7, 10, 15) distributed within six cluster diameters (1, 3, 5, 6, 8, 10 mm) were simulated to study the effect of cluster density. To study the role of image display method, 2D regions of interest (ROIs) and 3D volumes of interest (VOIs) were generated using single slice extraction, slice averaging, and maximum-intensity projection (MIP). 2D and 3D CNNs were trained on the ROIs and VOIs, and receiver operating characteristic (ROC) curve analysis was used to evaluate detection performance. The area under the ROC curve (AUC) was used as the primary performance metric. RESULTS Detection performance decreased with increasing section thickness, and peak detection performance occurred using the native section thickness (0.2 mm) and MIP display. The MIP display method, despite using a single slice, yielded comparable performance to the native section thickness, which employed 50 slices. Reduction in slices did not sacrifice detection accuracy and provided significant computational advantages over multi-slice image volumes. Larger cluster diameters resulted in reduced overall detectability, while smaller cluster diameters led to increased detectability. Additionally, we observed that the presence of more calcifications within a cluster improved the overall detectability, while fewer calcifications decreased it. CONCLUSIONS As breast CT is still a relatively new breast imaging modality, there is an ongoing need to identify optimal imaging protocols. This work demonstrated the utility of MIP presentation for displaying image volumes containing microcalcification clusters. It is likely that human observers may also benefit from viewing MIPs compared to individual slices. The results of this investigation begin to elucidate how model observers interact with microcalcification clusters in a 3D volume, and will be useful for future studies investigating a broader set of parameters related to breast CT.
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Affiliation(s)
- Su Hyun Lyu
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95618, USA
- Department of Radiology, University of California Davis, Sacramento, CA, 95817, USA
| | - Craig K. Abbey
- Department of Psychological and Brain Sciences, UC Santa Barbara, Santa Barbara, CA, 93106 USA
| | - Andrew M. Hernandez
- Department of Radiology, University of California Davis, Sacramento, CA, 95817, USA
| | - John M. Boone
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95618, USA
- Department of Radiology, University of California Davis, Sacramento, CA, 95817, USA
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Fu Z, Tseng HW, Vedantham S. An attenuation field network for dedicated cone beam breast CT with short scan and offset detector geometry. Sci Rep 2024; 14:319. [PMID: 38172250 PMCID: PMC10764954 DOI: 10.1038/s41598-023-51077-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 12/30/2023] [Indexed: 01/05/2024] Open
Abstract
The feasibility of full-scan, offset-detector geometry cone-beam CT has been demonstrated for several clinical applications. For full-scan acquisition with offset-detector geometry, data redundancy from complementary views can be exploited during image reconstruction. Envisioning an upright breast CT system, we propose to acquire short-scan data in conjunction with offset-detector geometry. To tackle the resulting incomplete data, we have developed a self-supervised attenuation field network (AFN). AFN leverages the inherent redundancy of cone-beam CT data through coordinate-based representation and known imaging physics. A trained AFN can query attenuation coefficients using their respective coordinates or synthesize projection data including the missing projections. The AFN was evaluated using clinical cone-beam breast CT datasets (n = 50). While conventional analytical and iterative reconstruction methods failed to reconstruct the incomplete data, AFN reconstruction was not statistically different from the reference reconstruction obtained using full-scan, full-detector data in terms of image noise, image contrast, and the full width at half maximum of calcifications. This study indicates the feasibility of a simultaneous short-scan and offset-detector geometry for dedicated breast CT imaging. The proposed AFN technique can potentially be expanded to other cone-beam CT applications.
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Affiliation(s)
- Zhiyang Fu
- Department of Medical Imaging, The University of Arizona, 1501 N. Campbell Ave, Tucson, AZ, 85724, USA
| | - Hsin Wu Tseng
- Department of Medical Imaging, The University of Arizona, 1501 N. Campbell Ave, Tucson, AZ, 85724, USA
| | - Srinivasan Vedantham
- Department of Medical Imaging, The University of Arizona, 1501 N. Campbell Ave, Tucson, AZ, 85724, USA.
- Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, USA.
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Lyu SH, Abbey CK, Hernandez AM, Boone JM. Pre-whitened matched filter and convolutional neural network based model observer performance for mass lesion detection in non-contrast breast CT. Med Phys 2023; 50:7558-7567. [PMID: 37646463 PMCID: PMC10841056 DOI: 10.1002/mp.16685] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/27/2023] [Accepted: 08/06/2023] [Indexed: 09/01/2023] Open
Abstract
BACKGROUND Mathematical model observers have been shown to reasonably predict human observer performance and are useful when human observer studies are infeasible. Recently, convolutional neural networks (CNNs) have also been used as substitutes for human observers, and studies have shown their utility as an optimal observer. In this study, a CNN model observer is compared to the pre-whitened matched filter (PWMF) model observer in detecting simulated mass lesions inserted into 253 acquired breast computed tomography (bCT) images from patients imaged at our institution. PURPOSE To compare CNN and PWMF model observers for detecting signal-known-exactly (SKE) location-known-exactly (LKE) simulated lesions in bCT images with real anatomical backgrounds, and to use these model observers collectively to optimize parameters and understand trends in performance with breast CT. METHODS Spherical lesions with different diameters (1, 3, 5, 9 mm) were mathematically inserted into reconstructed patient bCT image data sets to mimic 3D mass lesions in the breast. 2D images were generated by extracting the center slice along the axial dimension or by slice averaging across adjacent slices to model thicker sections (0.4, 1.2, 2.0, 6.0, 12.4, 20.4 mm). The role of breast density was retrospectively studied using the range of breast densities intrinsic to the patient bCT data sets. In addition, mass lesions were mathematically inserted into Gaussian images matched to the mean and noise power spectrum of the bCT images to better understand the performance of the CNN in the context of a known ideal observer (the PWMF). The simulated Gaussian and bCT images were divided into training and testing data sets. Each training data set consisted of 91 600 images, and each testing data set consisted of 96 000 images. A CNN and PWMF was trained on the Gaussian training images, and a different CNN and PWMF was trained on the bCT training images. The trained model observers were tested, and receiver operating characteristic (ROC) curve analysis was used to evaluate detection performance. The area under the ROC curve (AUC) was the primary performance metric used to compare the model observers. RESULTS In the Gaussian background, the CNN performed essentially identically to the PWMF across lesion sizes and section thicknesses. In the bCT background, the CNN outperformed the PWMF across lesion size, breast density, and most section thicknesses. These findings suggest that there are higher-order features in bCT images that are harnessed by the CNN observer but are inaccessible to the PWMF. CONCLUSIONS The CNN performed equivalently to the ideal observer in Gaussian textures. In bCT background, the CNN captures more diagnostic information than the PWMF and may be a more pertinent observer when conducting optimal performance studies in breast CT images.
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Affiliation(s)
- Su Hyun Lyu
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95618, USA
- Department of Radiology, University of California Davis, Sacramento, CA, 95817, USA
| | - Craig K. Abbey
- Department of Psychological and Brain Sciences, UC Santa Barbara, Santa Barbara, CA, 93106 USA
| | - Andrew M. Hernandez
- Department of Radiology, University of California Davis, Sacramento, CA, 95817, USA
| | - John M. Boone
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95618, USA
- Department of Radiology, University of California Davis, Sacramento, CA, 95817, USA
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Vedantham S, Tseng HW, Fu Z, Chow HHS. Dedicated Cone-Beam Breast CT: Reproducibility of Volumetric Glandular Fraction with Advanced Image Reconstruction Methods. Tomography 2023; 9:2039-2051. [PMID: 37987346 PMCID: PMC10661286 DOI: 10.3390/tomography9060160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 10/06/2023] [Accepted: 10/20/2023] [Indexed: 11/22/2023] Open
Abstract
Dedicated cone-beam breast computed tomography (CBBCT) is an emerging modality and provides fully three-dimensional (3D) images of the uncompressed breast at an isotropic voxel resolution. In an effort to translate this modality to breast cancer screening, advanced image reconstruction methods are being pursued. Since radiographic breast density is an established risk factor for breast cancer and CBBCT provides volumetric data, this study investigates the reproducibility of the volumetric glandular fraction (VGF), defined as the proportion of fibroglandular tissue volume relative to the total breast volume excluding the skin. Four image reconstruction methods were investigated: the analytical Feldkamp-Davis-Kress (FDK), a compressed sensing-based fast, regularized, iterative statistical technique (FRIST), a fully supervised deep learning approach using a multi-scale residual dense network (MS-RDN), and a self-supervised approach based on Noise-to-Noise (N2N) learning. Projection datasets from 106 women who participated in a prior clinical trial were reconstructed using each of these algorithms at a fixed isotropic voxel size of (0.273 mm3). Each reconstructed breast volume was segmented into skin, adipose, and fibroglandular tissues, and the VGF was computed. The VGF did not differ among the four reconstruction methods (p = 0.167), and none of the three advanced image reconstruction algorithms differed from the standard FDK reconstruction (p > 0.862). Advanced reconstruction algorithms developed for low-dose CBBCT reproduce the VGF to provide quantitative breast density, which can be used for risk estimation.
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Affiliation(s)
- Srinivasan Vedantham
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724, USA; (H.W.T.); (Z.F.)
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ 85724, USA
| | - Hsin Wu Tseng
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724, USA; (H.W.T.); (Z.F.)
| | - Zhiyang Fu
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724, USA; (H.W.T.); (Z.F.)
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Lyu SH, Hernandez AM, Shakeri SA, Abbey CK, Boone JM. Model observer performance in contrast-enhanced lesions in breast CT: The influence of contrast concentration on detectability. Med Phys 2023; 50:6748-6761. [PMID: 37639329 PMCID: PMC10847956 DOI: 10.1002/mp.16667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 07/13/2023] [Accepted: 07/15/2023] [Indexed: 08/31/2023] Open
Abstract
BACKGROUND The use of iodine-based contrast agent for better delineation of tumors in breast CT (bCT) has been shown to be compelling, similar to the tumor enhancement in contrast-enhanced breast MRI. Contrast-enhanced bCT (CE-bCT) is a relatively new tool, and a structured evaluation of different imaging parameters at play has yet to be conducted. In this investigation, data sets of acquired bCT images from 253 patients imaged at our institution were used in concert with simulated mathematically inserted spherical contrast-enhanced lesions to study the role of contrast enhancement on detectability. PURPOSE To quantitatively evaluate the improvement in lesion detectability due to contrast enhancement across lesion diameter, section thickness, view plane, and breast density using a pre-whitened matched filter (PWMF) model observer. METHODS The relationship between iodine concentration and Hounsfield units (HU) was measured using spectral modeling. The lesion enhancement from clinical CE-bCT images in 22 patients was evaluated, and the average contrast enhancement (ΔHU) was determined. Mathematically generated spherical mass lesions of varying diameters (1, 3, 5, 9, 11, 15 mm) and contrast enhancement levels (0, 0.25, 0.50, 0.75, 1) were inserted at random locations in 253 actual patient bCT datasets. Images with varying thicknesses (0.4-19.8 mm) were generated by slice averaging, and the role of view plane (coronal and axial planes) was studied. A PWMF was used to generate receiver operating characteristic (ROC) curves across parameters of lesion diameter, contrast enhancement, section thickness, view plane, and breast density. The area under the ROC curve (AUC) was used as the primary performance metric, generated from over 90,000 simulated lesions. RESULTS An average 20% improvement (ΔAUC = 0.1) in lesion detectability due to contrast enhancement was observed across lesion diameter, section thickness, breast density, and view plane. A larger improvement was observed when stratifying patients based on breast density. For patients with VGF ≤ 40%, detection performance improved up to 20% (until AUC →1), and for patients with denser breasts (VGF > 40%), detection performance improved more drastically, ranging from 20% to 80% for 1- and 5-mm lesions. For the 1 mm lesion, detection performance raised slightly at the 1.2 mm section thickness before falling off as thickness increased. For larger lesions, detection performance was generally unaffected as section thickness increased up until it reached 5.8 mm, where performance began to decline. Detection performance was higher in the axial plane compared to the coronal plane for smaller lesions and thicker sections. CONCLUSIONS For emerging diagnostic tools like CE-bCT, it is important to optimize imaging protocols for lesion detection. In this study, we found that intravenous contrast can be used to detect small lesions in dense breasts. Optimal section thickness for detectability has dependencies on breast density and lesion size, therefore, display thickness should be adjusted in real-time using display software. These findings may be useful for the development of CE-bCT as well as other x-ray-based breast imaging modalities.
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Affiliation(s)
- Su Hyun Lyu
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95618, USA
- Department of Radiology, University of California Davis, Sacramento, CA, 95817, USA
| | - Andrew M. Hernandez
- Department of Radiology, University of California Davis, Sacramento, CA, 95817, USA
| | | | - Craig K. Abbey
- Department of Psychological and Brain Sciences, UC Santa Barbara, Santa Barbara, CA, 93106 USA
| | - John M. Boone
- Department of Biomedical Engineering, University of California Davis, Davis, CA, 95618, USA
- Department of Radiology, University of California Davis, Sacramento, CA, 95817, USA
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Weaver OO, Kornecki A, Yang WT. Reply to: "Expanding Biopsy Options for Suspicious Breast Lesions: CT-Guided Biopsy Using a 3D-Printed Device". AJR Am J Roentgenol 2023; 221:402. [PMID: 37406201 DOI: 10.2214/ajr.23.29476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2023]
Affiliation(s)
- Olena O Weaver
- The University of Texas MD Anderson Cancer Center, Houston, TX, , @OWeaverMD
| | - Anat Kornecki
- Western University, St. Joseph Health Care, London, ON, Canada
| | - Wei T Yang
- The University of Texas MD Anderson Cancer Center, Houston, TX
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Physical and digital phantoms for 2D and 3D x-ray breast imaging: Review on the state-of-the-art and future prospects. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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12
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Tseng HW, Karellas A, Vedantham S. Cone-beam breast CT using an offset detector: effect of detector offset and image reconstruction algorithm. Phys Med Biol 2022; 67. [PMID: 35316793 PMCID: PMC9045275 DOI: 10.1088/1361-6560/ac5fe1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 03/22/2022] [Indexed: 11/12/2022]
Abstract
Objective.A dedicated cone-beam breast computed tomography (BCT) using a high-resolution, low-noise detector operating in offset-detector geometry has been developed. This study investigates the effects of varying detector offsets and image reconstruction algorithms to determine the appropriate combination of detector offset and reconstruction algorithm.Approach.Projection datasets (300 projections in 360°) of 30 breasts containing calcified lesions that were acquired using a prototype cone-beam BCT system comprising a 40 × 30 cm flat-panel detector with 1024 × 768 detector pixels were reconstructed using Feldkamp-Davis-Kress (FDK) algorithm and served as the reference. The projection datasets were retrospectively truncated to emulate cone-beam datasets with sinograms of 768×768 and 640×768 detector pixels, corresponding to 5 cm and 7.5 cm lateral offsets, respectively. These datasets were reconstructed using the FDK algorithm with appropriate weights and an ASD-POCS-based Fast, total variation-Regularized, Iterative, Statistical reconstruction Technique (FRIST), resulting in a total of 4 offset-detector reconstructions (2 detector offsets × 2 reconstruction methods). Signal difference-to-noise ratio (SDNR), variance, and full-width at half-maximum (FWHM) of calcifications in two orthogonal directions were determined from all reconstructions. All quantitative measurements were performed on images in units of linear attenuation coefficient (1/cm).Results.The FWHM of calcifications did not differ (P > 0.262) among reconstruction algorithms and detector formats, implying comparable spatial resolution. For a chosen detector offset, the FRIST algorithm outperformed FDK in terms of variance and SDNR (P < 0.0001). For a given reconstruction method, the 5 cm offset provided better results.Significance.This study indicates the feasibility of using the compressed sensing-based, FRIST algorithm to reconstruct sinograms from offset-detectors. Among the reconstruction methods and detector offsets studied, FRIST reconstructions corresponding to a 30 cm × 30 cm with 5 cm lateral offset, achieved the best performance. A clinical prototype using such an offset geometry has been developed and installed for clinical trials.
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Affiliation(s)
- Hsin Wu Tseng
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, United States of America
| | - Andrew Karellas
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, United States of America
| | - Srinivasan Vedantham
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, United States of America.,Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, United States of America
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13
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Sarno A, Mettivier G, Bliznakova K, Hernandez AM, Boone JM, Russo P. Comparisons of glandular breast dose between digital mammography, tomosynthesis and breast CT based on anthropomorphic patient-derived breast phantoms. Phys Med 2022; 97:50-58. [PMID: 35395535 DOI: 10.1016/j.ejmp.2022.03.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/17/2022] [Accepted: 03/26/2022] [Indexed: 11/30/2022] Open
Abstract
PURPOSE To evaluate the bias to the mean glandular dose (MGD) estimates introduced by the homogeneous breast models in digital breast tomosynthesis (DBT) and to have an insight into the glandular dose distributions in 2D (digital mammography, DM) and 3D (DBT and breast dedicated CT, BCT) x-ray breast imaging by employing breast models with realistic glandular tissue distribution and organ silhouette. METHODS A Monte Carlo software for DM, DBT and BCT simulations was adopted for the evaluation of glandular dose distribution in 60 computational anthropomorphic phantoms. These computational phantoms were derived from 3D breast images acquired via a clinical BCT scanner. RESULTS g·c·s·T conversion coefficients based on homogeneous breast model led to a MGD overestimate of 18% in DBT when compared to MGD estimated via anthropomorphic phantoms; this overestimate increased up to 21% for recently computed DgNDBT conversion coefficients. The standard deviation of the glandular dose distribution in BCT resulted 60% lower than in DM and 55% lower than in DBT. The glandular dose peak - evaluated as the average value over the 5% of the gland receiving the highest dose - is 2.8 times the MGD in DM, this factor reducing to 2.6 and 1.6 in DBT and BCT, respectively. CONCLUSIONS Conventional conversion coefficients for MGD estimates based on homogeneous breast models overestimate MGD by 18%, when compared to MGD estimated via anthropomorphic phantoms. The ratio between the peak glandular dose and the MGD is 2.8 in DM. This ratio is 8% and 75% higher than in DBT and BCT, respectively.
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Affiliation(s)
- Antonio Sarno
- University of Naples Federico II, Dept. of Physics "Ettore Pancini", Naples, Italy; INFN Division of Naples, Naples, Italy.
| | - Giovanni Mettivier
- University of Naples Federico II, Dept. of Physics "Ettore Pancini", Naples, Italy; INFN Division of Naples, Naples, Italy
| | | | | | - John M Boone
- University of California Davis Medical Center, Sacramento, CA, USA
| | - Paolo Russo
- University of Naples Federico II, Dept. of Physics "Ettore Pancini", Naples, Italy; INFN Division of Naples, Naples, Italy
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Ghazi P, Youssefian S, Ghazi T. A novel hardware duo of beam modulation and shielding to reduce scatter acquisition and dose in cone-beam breast CT. Med Phys 2021; 49:169-185. [PMID: 34825715 DOI: 10.1002/mp.15374] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 11/07/2021] [Accepted: 11/12/2021] [Indexed: 12/12/2022] Open
Abstract
PURPOSE In cone-beam breast CT, scattered photons form a large portion of the acquired signal, adversely impacting image quality throughout the frequency response of the imaging system. Prior simulation studies provided proof of concept for utilization of a hardware solution to prevent scatter acquisition. Here, we report the design, implementation, and characterization of an auxiliary apparatus of fluence modulation and scatter shielding that does indeed lead to projections with a reduced level of scatter. METHODS An apparatus was designed for permanent installation within an existing cone-beam CT system. The apparatus is composed of two primary assemblies: a "Fluence Modulator" (FM) and a "Scatter Shield" (SS). The design of the assemblies enables them to operate in synchrony during image acquisition, converting the sourced x-rays into a moving narrow beam. During a projection, this narrow beam sweeps the entire fan angle coverage of the imaging system. As the two assemblies are contingent on one another, their joint implementation is described in the singular as apparatus FM-SS. The FM and the SS assemblies are each comprised a metal housing, a sensory system, and a robotic system. A controller unit handles their relative movements. A series of comparative studies were conducted to evaluate the performance of a cone-beam CT system in two "modes" of operation: with and without FM-SS installed, and to compare the results of physical implementation with those previously simulated. The dynamic range requirements of the utilized detector in the cone-beam CT imaging system were first characterized, independent of the mode of operation. We then characterized and compared the spatial resolution of the imaging system with, and without, FM-SS. A physical breast phantom, representative of an average size breast, was developed and imaged. Actual differences in signal level obtained with, versus without, FM-SS were then compared to the expected level gains based on previously reported simulations. Following these initial assessments, the scatter acquisition in each projection in both modes of operation was investigated. Finally, as an initial study of the impact of FM-SS on radiation dose in an average size breast, a series of Monte Carlo simulations were coupled with physical measurements of air kerma, with and without FM-SS. RESULTS With implementation of FM-SS, the detector's required dynamic range was reduced by a factor of 5.5. Substantial reduction in the acquisition of the scattered rays, by a factor of 5.1 was achieved. With the implementation of FM-SS, deposited dose was reduced by 27% in the studied breast. CONCLUSIONS The disclosed implementation of FM-SS, within a cone-beam breast CT system, results in reduction of scatter-components in acquired projections, reduction of dose deposit to the breast, and relaxation of requirements for the detector's dynamic range. Controlling or correcting for patient motion occurring during image acquisition remains an open problem to be solved prior to practical clinical usage of FM-SS cone-beam breast CT.
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Fahrig R, Jaffray DA, Sechopoulos I, Webster Stayman J. Flat-panel conebeam CT in the clinic: history and current state. J Med Imaging (Bellingham) 2021; 8:052115. [PMID: 34722795 DOI: 10.1117/1.jmi.8.5.052115] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 09/27/2021] [Indexed: 11/14/2022] Open
Abstract
Research into conebeam CT concepts began as soon as the first clinical single-slice CT scanner was conceived. Early implementations of conebeam CT in the 1980s focused on high-contrast applications where concurrent high resolution ( < 200 μ m ), for visualization of small contrast-filled vessels, bones, or teeth, was an imaging requirement that could not be met by the contemporaneous CT scanners. However, the use of nonlinear imagers, e.g., x-ray image intensifiers, limited the clinical utility of the earliest diagnostic conebeam CT systems. The development of consumer-electronics large-area displays provided a technical foundation that was leveraged in the 1990s to first produce large-area digital x-ray detectors for use in radiography and then compact flat panels suitable for high-resolution and high-frame-rate conebeam CT. In this review, we show the concurrent evolution of digital flat panel (DFP) technology and clinical conebeam CT. We give a brief summary of conebeam CT reconstruction, followed by a brief review of the correction approaches for DFP-specific artifacts. The historical development and current status of flat-panel conebeam CT in four clinical areas-breast, fixed C-arm, image-guided radiation therapy, and extremity/head-is presented. Advances in DFP technology over the past two decades have led to improved visualization of high-contrast, high-resolution clinical tasks, and image quality now approaches the soft-tissue contrast resolution that is the standard in clinical CT. Future technical developments in DFPs will enable an even broader range of clinical applications; research in the arena of flat-panel CT shows no signs of slowing down.
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Affiliation(s)
- Rebecca Fahrig
- Innovation, Advanced Therapies, Siemens Healthcare GmbH, Forchheim, Germany.,Friedrich-Alexander Universitat, Department of Computer Science 5, Erlangen, Germany
| | - David A Jaffray
- MD Anderson Cancer Center, Departments of Radiation Physics and Imaging Physics, Houston, Texas, United States
| | - Ioannis Sechopoulos
- Radboud University Medical Center, Department of Medical Imaging, Nijmegen, The Netherlands.,Dutch Expert Center for Screening (LRCB), Nijmegen, The Netherlands.,University of Twente, Technical Medical Center, Enschede, The Netherlands
| | - J Webster Stayman
- Johns Hopkins University, Department of Biomedical Engineering, Baltimore, Maryland, United States
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16
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Dedicated breast CT: state of the art-Part I. Historical evolution and technical aspects. Eur Radiol 2021; 32:1579-1589. [PMID: 34342694 DOI: 10.1007/s00330-021-08179-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 06/19/2021] [Accepted: 06/29/2021] [Indexed: 12/24/2022]
Abstract
Dedicated breast CT is an emerging 3D isotropic imaging technology for breast, which overcomes the limitations of 2D compression mammography and limited angle tomosynthesis while providing some of the advantages of magnetic resonance imaging. This first installment in a 2-part review describes the evolution of dedicated breast CT beginning with a historical perspective and progressing to the present day. Moreover, it provides an overview of state-of-the-art technology. Particular emphasis is placed on technical limitations in scan protocol, radiation dose, breast coverage, patient comfort, and image artifact. Proposed methods of how to address these technical challenges are also discussed. KEY POINTS: • Advantages of breast CT include no tissue overlap, improved patient comfort, rapid acquisition, and concurrent assessment of microcalcifications and contrast enhancement. • Current clinical and prototype dedicated breast CT systems differ in acquisition modes, imaging techniques, and detector types. • There are still details to be decided regarding breast CT techniques, such as scan protocol, radiation dose, breast coverage, patient comfort, and image artifact.
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17
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Tseng HW, Karellas A, Vedantham S. Radiation dosimetry of a clinical prototype dedicated cone-beam breast CT system with offset detector. Med Phys 2021; 48:1079-1088. [PMID: 33501686 DOI: 10.1002/mp.14688] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 12/27/2022] Open
Abstract
PURPOSE A clinical-prototype, dedicated, cone-beam breast computed tomography (CBBCT) system with offset detector is undergoing clinical evaluation at our institution. This study is to estimate the normalized glandular dose coefficients ( DgN CT ) that provide air kerma-to-mean glandular dose conversion factors using Monte Carlo simulations. MATERIALS AND METHODS The clinical prototype CBBCT system uses 49 kV x-ray spectrum with 1.39 mm 1st half-value layer thickness. Monte Carlo simulations (GATE, version 8) were performed with semi-ellipsoidal, homogeneous breasts of various fibroglandular weight fractions ( f g = 0.01 , 0.15 , 0.5 , 1 ) , chest wall diameters ( d = 8 , 10 , 14 , 18 , 20 cm), and chest wall to nipple length ( l = 0.75 d ), aligned with the axis of rotation (AOR) located at 65 cm from the focal spot to determine the DgN CT . Three geometries were considered - 40 × 30 -cm detector with no offset that served as reference and corresponds to a clinical CBBCT system, 30 × 30 -cm detector with 5 cm offset, and a 30 × 30 -cm detector with 10 cm offset. RESULTS For 5 cm lateral offset, the DgN CT ranged 0.177 - 0.574 mGy/mGy and reduction in DgN CT with respect to reference geometry was observed only for 18 cm ( 6.4 % ± 0.23 % ) and 20 cm ( 9.6 % ± 0.22 % ) diameter breasts. For the 10 cm lateral offset, the DgN CT ranged 0.221 - 0.581 mGy/mGy and reduction in DgN CT was observed for all breast diameters. The reduction in DgN CT was 1.4 % ± 0.48 % , 7.1 % ± 0.13 % , 17.5 % ± 0.19 % , 25.1 % ± 0.15 % , and 27.7 % ± 0.08 % for 8, 10, 14, 18, and 20 cm diameter breasts, respectively. For a given breast diameter, the reduction in DgN CT with offset-detector geometries was not dependent on f g . Numerical fits of DgN CT d , l , f g were generated for each geometry. CONCLUSION The DgN CT and the numerical fit, D g N CT d , l , f g would be of benefit for current CBBCT systems using the reference geometry and for future generations using offset-detector geometry. There exists a potential for radiation dose reduction with offset-detector geometry, provided the same technique factors as the reference geometry are used, and the image quality is clinically acceptable.
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Affiliation(s)
- Hsin Wu Tseng
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, USA
| | - Andrew Karellas
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, USA
| | - Srinivasan Vedantham
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, USA.,Department of Biomedical Engineering, The University of Arizona, Tucson, AZ, USA
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19
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Becker AE, Hernandez AM, Schwoebel PR, Boone JM. Cone beam CT multisource configurations: evaluating image quality, scatter, and dose using phantom imaging and Monte Carlo simulations. ACTA ACUST UNITED AC 2020; 65:235032. [DOI: 10.1088/1361-6560/abc306] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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20
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Ghazi P. Reduction of scatter in breast CT yields improved microcalcification visibility. Phys Med Biol 2020; 65:235047. [PMID: 33274730 DOI: 10.1088/1361-6560/abae07] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The inadequate visibility of microcalcifications-small calcium deposits that cue radiologists to early stages of cancer-is a major limitation in current designs of dedicated breast computed tomography (bCT). This limitation has previously been attributed to the constituent components, spatial resolution, and utilized dose. Scattered radiation has been considered an occurrence with low-frequency impacts that can be compensated for in post-processing. We hypothesized, however, that the acquisition of scattered radiation has a far more detrimental impact on clinically relevant features than has previously been understood. Critically, acquisition of scatter leads to the reduced visibility of microcalcifications. This hypothesis was investigated and supported via mathematical derivations and simulation studies. We conducted a series of comparative studies in which four bCT systems were simulated under iso-dose and iso-resolution conditions, characterizing the dependencies of microcalcification contrast on accumulated scatter. Included among the simulated systems is a novel bCT design-narrow beam bCT (NB-bCT)-that captures nearly zero scatter. We find that current bCT systems suffer from significant levels of scatter. As validated in theory, depending on the system and size of microcalcifications, between 25% and over 70% of contrast resolution is lost due to scatter. The results in NB-bCT, however, provide evidence that by removing scatter build-up in projections, the contrast of microcalcifications in a bCT image is preserved, regardless of their size or location in the breast.
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Affiliation(s)
- Peymon Ghazi
- Malcova LLC, 3000 Falls Rd Suite 400, Baltimore, MD 21211, United States of America
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21
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Fu Z, Tseng HW, Vedantham S, Karellas A, Bilgin A. A residual dense network assisted sparse view reconstruction for breast computed tomography. Sci Rep 2020; 10:21111. [PMID: 33273541 PMCID: PMC7713379 DOI: 10.1038/s41598-020-77923-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 11/18/2020] [Indexed: 12/24/2022] Open
Abstract
To develop and investigate a deep learning approach that uses sparse-view acquisition in dedicated breast computed tomography for radiation dose reduction, we propose a framework that combines 3D sparse-view cone-beam acquisition with a multi-slice residual dense network (MS-RDN) reconstruction. Projection datasets (300 views, full-scan) from 34 women were reconstructed using the FDK algorithm and served as reference. Sparse-view (100 views, full-scan) projection data were reconstructed using the FDK algorithm. The proposed MS-RDN uses the sparse-view and reference FDK reconstructions as input and label, respectively. Our MS-RDN evaluated with respect to fully sampled FDK reference yields superior performance, quantitatively and visually, compared to conventional compressed sensing methods and state-of-the-art deep learning based methods. The proposed deep learning driven framework can potentially enable low dose breast CT imaging.
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Affiliation(s)
- Zhiyang Fu
- Department of Medical Imaging, University of Arizona, Tucson, AZ, USA.,Department of Electrical and Computer Engineering, University of Arizona, Tucson, AZ, USA
| | - Hsin Wu Tseng
- Department of Medical Imaging, University of Arizona, Tucson, AZ, USA
| | - Srinivasan Vedantham
- Department of Medical Imaging, University of Arizona, Tucson, AZ, USA.,Department of Biomedical Engineering, University of Arizona, Tucson, AZ, USA
| | - Andrew Karellas
- Department of Medical Imaging, University of Arizona, Tucson, AZ, USA
| | - Ali Bilgin
- Department of Medical Imaging, University of Arizona, Tucson, AZ, USA. .,Department of Electrical and Computer Engineering, University of Arizona, Tucson, AZ, USA. .,Department of Biomedical Engineering, University of Arizona, Tucson, AZ, USA.
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22
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Mettivier G, Masi M, Arfelli F, Brombal L, Delogu P, Di Lillo F, Donato S, Fedon C, Golosio B, Oliva P, Rigon L, Sarno A, Taibi A, Russo P. Radiochromic film dosimetry in synchrotron radiation breast computed tomography: a phantom study. JOURNAL OF SYNCHROTRON RADIATION 2020; 27:762-771. [PMID: 32381779 PMCID: PMC7285685 DOI: 10.1107/s1600577520001745] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 02/07/2020] [Indexed: 06/11/2023]
Abstract
This study relates to the INFN project SYRMA-3D for in vivo phase-contrast breast computed tomography using the SYRMEP synchrotron radiation beamline at the ELETTRA facility in Trieste, Italy. This peculiar imaging technique uses a novel dosimetric approach with respect to the standard clinical procedure. In this study, optimization of the acquisition procedure was evaluated in terms of dose delivered to the breast. An offline dose monitoring method was also investigated using radiochromic film dosimetry. Various irradiation geometries have been investigated for scanning the prone patient's pendant breast, simulated by a 14 cm-diameter polymethylmethacrylate cylindrical phantom containing pieces of calibrated radiochromic film type XR-QA2. Films were inserted mid-plane in the phantom, as well as wrapped around its external surface, and irradiated at 38 keV, with an air kerma value that would produce an estimated mean glandular dose of 5 mGy for a 14 cm-diameter 50% glandular breast. Axial scans were performed over a full rotation or over 180°. The results point out that a scheme adopting a stepped rotation irradiation represents the best geometry to optimize the dose distribution to the breast. The feasibility of using a piece of calibrated radiochromic film wrapped around a suitable holder around the breast to monitor the scan dose offline is demonstrated.
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Affiliation(s)
- Giovanni Mettivier
- Dipartimento di Fisica ‘Ettore Pancini’, Università di Napoli ‘Federico II’, I-80126 Napoli, Italy
- INFN, Sezione di Napoli, I-80126 Napoli, Italy
| | - Marica Masi
- Dipartimento di Fisica ‘Ettore Pancini’, Università di Napoli ‘Federico II’, I-80126 Napoli, Italy
- INFN, Sezione di Napoli, I-80126 Napoli, Italy
| | - Fulvia Arfelli
- Department of Physics, Università di Trieste, I-34127 Trieste, Italy
- Sezione di Trieste, INFN, I-34127 Trieste, Italy
| | - Luca Brombal
- Department of Physics, Università di Trieste, I-34127 Trieste, Italy
- Sezione di Trieste, INFN, I-34127 Trieste, Italy
| | - Pasquale Delogu
- Department of Physical Science, Earth and Environment, Università di Siena, I-53100 Siena, Italy
- Sezione di Pisa, INFN, I-34127 Pisa, Italy
| | - Francesca Di Lillo
- Dipartimento di Fisica ‘Ettore Pancini’, Università di Napoli ‘Federico II’, I-80126 Napoli, Italy
- INFN, Sezione di Napoli, I-80126 Napoli, Italy
- ELETTRA-Sincrotrone Trieste SCpA, Bassovizza, I-34149 Trieste, Italy
| | - Sandro Donato
- Department of Physics, Università di Trieste, I-34127 Trieste, Italy
- Sezione di Trieste, INFN, I-34127 Trieste, Italy
| | - Christian Fedon
- Sezione di Trieste, INFN, I-34127 Trieste, Italy
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, 6500 HB Nijmegen, The Netherlands
| | - Bruno Golosio
- Department of Physics, Università di Cagliari, I-09042 Cagliari, Italy
- Sezione di Cagliari, INFN, I-09042 Cagliari, Italy
| | - Piernicola Oliva
- Sezione di Cagliari, INFN, I-09042 Cagliari, Italy
- Department of Chemistry and Pharmacy, Università di Sassari, Sassari, Italy
| | - Luigi Rigon
- Department of Physics, Università di Trieste, I-34127 Trieste, Italy
- Sezione di Trieste, INFN, I-34127 Trieste, Italy
| | | | - Angelo Taibi
- Department of Physics and Earth Science, Università di Ferrara, I-44122 Ferrara, Italy
- Sezione di Ferrara, INFN, I-44122 Ferrara, Italy
| | - Paolo Russo
- Dipartimento di Fisica ‘Ettore Pancini’, Università di Napoli ‘Federico II’, I-80126 Napoli, Italy
- INFN, Sezione di Napoli, I-80126 Napoli, Italy
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23
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Tseng HW, Vedantham S, Karellas A. Cone-beam breast computed tomography using ultra-fast image reconstruction with constrained, total-variation minimization for suppression of artifacts. Phys Med 2020; 73:117-124. [PMID: 32361156 DOI: 10.1016/j.ejmp.2020.04.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/31/2020] [Accepted: 04/21/2020] [Indexed: 12/18/2022] Open
Abstract
Compressed sensing based iterative reconstruction algorithms for computed tomography such as adaptive steepest descent-projection on convex sets (ASD-POCS) are attractive due to their applicability in incomplete datasets such as sparse-view data and can reduce radiation dose to the patients while preserving image quality. Although IR algorithms reduce image noise compared to analytical Feldkamp-Davis-Kress (FDK) algorithm, they may generate artifacts, particularly along the periphery of the object. One popular solution is to use finer image-grid followed by down-sampling. This approach is computationally intensive but may be compensated by reducing the field of view. Our proposed solution is to replace the algebraic reconstruction technique within the original ASD-POCS by ordered subsets-simultaneous algebraic reconstruction technique (OS-SART) and with initialization using FDK image. We refer to this method as Fast, Iterative, TV-Regularized, Statistical reconstruction Technique (FIRST). In this study, we investigate FIRST for cone-beam dedicated breast CT with large image matrix. The signal-difference to noise ratio (SDNR), the difference of the mean value and the variance of adipose and fibroglandular tissues for both FDK and FIRST reconstructions were determined. With FDK serving as the reference, the root-mean-square error (RMSE), bias, and the full-width at half-maximum (FWHM) of microcalcifications in two orthogonal directions were also computed. Our results suggest that FIRST is competitive to the finer image-grid method with shorter reconstruction time. Images reconstructed using the FIRST do not exhibit artifacts and outperformed FDK in terms of image noise. This suggests the potential of this approach for radiation dose reduction in cone-beam breast CT.
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Affiliation(s)
- Hsin Wu Tseng
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724, United States
| | - Srinivasan Vedantham
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724, United States; Department of Biomedical Engineering, University of Arizona, Tucson, AZ 85724, United States
| | - Andrew Karellas
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724, United States.
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24
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Hernandez AM, Abbey CK, Ghazi P, Burkett G, Boone JM. Effects of kV, filtration, dose, and object size on soft tissue and iodine contrast in dedicated breast CT. Med Phys 2020; 47:2869-2880. [PMID: 32233091 DOI: 10.1002/mp.14159] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/30/2019] [Accepted: 03/13/2020] [Indexed: 01/07/2023] Open
Abstract
PURPOSE Clinical use of dedicated breast computed tomography (bCT) requires relatively short scan times necessitating systems with high frame rates. This in turn impacts the x-ray tube operating range. We characterize the effects of tube voltage, beam filtration, dose, and object size on contrast and noise properties related to soft tissue and iodine contrast agents as a way to optimize imaging protocols for soft tissue and iodine contrast at high frame rates. METHODS This study design uses the signal-difference-to-noise ratio (SDNR), noise-equivalent quanta (NEQ), and detectability (d´) as measures of imaging performance for a prototype breast CT scanner that utilizes a pulsed x-ray tube (with a 4 ms pulse width) at 43.5 fps acquisition rate. We assess a range of kV, filtration, breast phantom size, and mean glandular dose (MGD). Performance measures are estimated from images of adipose-equivalent breast phantoms machined to have a representative size and shape of small, medium, and large breasts. Water (glandular tissue equivalent) and iodine contrast (5 mg/ml) were used to fill two cylindrical wells in the phantoms. RESULTS Air kerma levels required for obtaining an MGD of 6 mGy ranged from 7.1 to 9.1 mGy and are reported across all kV, filtration, and breast phantom sizes. However, at 50 kV, the thick filters (0.3 mm of Cu or Gd) exceeded the maximum available mA of the x-ray generator, and hence, these conditions were excluded from subsequent analysis. There was a strong positive association between measurements of SDNR and d' (R2 > 0.97) within the range of parameters investigated in this work. A significant decrease in soft tissue SDNR was observed for increasing phantom size and increasing kV with a maximum SDNR at 50 kV with 0.2 mm Cu or 0.2 mm Gd filtration. For iodine contrast SDNR, a significant decrease was observed with increasing phantom size, but a decrease in SDNR for increasing kV was only observed for 70 kV (50 and 60 kV were not significantly different). Thicker Gd filtration (0.3 mm Gd) resulted in a significant increase in iodine SDNR and decrease in soft tissue SDNR but requires significantly more tube current to deliver the same MGD. CONCLUSIONS The choice of 60 kV with 0.2 mm Gd filtration provides a good trade-off for maximizing both soft tissue and iodine contrast. This scanning technique takes advantage of the ~50 keV Gd k-edge to produce contrast and can be achieved within operating range of the x-ray generator used in this work. Imaging at 60 kV allows for a greater range in dose delivered to the large breast sizes when uniform image quality is desired across all breast sizes. While imaging performance metrics (i.e., detectability index and SDNR) were shown to be strongly correlated, the methodologies presented in this work for the estimation of NEQ (and subsequently d') provides a meaningful description of the spatial resolution and noise characteristics of this prototype bCT system across a range of beam quality, dose, and object sizes.
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Affiliation(s)
- Andrew M Hernandez
- Department of Radiology, University of California Davis, Sacramento, 95817, CA, USA
| | - Craig K Abbey
- Department of Psychological & Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | | | - George Burkett
- Department of Radiology, University of California Davis, Sacramento, 95817, CA, USA
| | - John M Boone
- Department of Radiology, University of California Davis, Sacramento, 95817, CA, USA.,Department of Biomedical Engineering, University of California Davis, Sacramento, CA, 95817, USA
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25
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Liang AK, El-Mohri Y, Zhao Q, Koniczek M, Antonuk LE. Count rate capabilities of polycrystalline silicon photon counting detectors for CBCT applications-a theoretical study. Phys Med Biol 2020; 65:035009. [PMID: 31874461 DOI: 10.1088/1361-6560/ab6577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The signal-to-noise properties of active matrix, flat-panel imagers (AMFPIs) limit the imaging performance of this x-ray imaging technology under conditions of low dose per image frame. This limitation can affect cone-beam computed tomography (CBCT) procedures where an AMFPI is used to acquire hundreds of image frames to form a single volumetric data set. An approach for overcoming this limitation is to replace the energy-integrating pixel circuits of AMFPI arrays with photon counting pixel circuits which examine the energy of each x-ray interaction and count those events whose signals exceed user-defined energy thresholds. A promising material for fabricating the circuits of such photon-counting detectors (PCDs) is polycrystalline silicon (poly-Si)-a semiconductor that facilitates economic manufacture of large area, monolithic arrays of the size presently provided by AMFPIs as well as provides good radiation damage resistance. In this paper, results are reported from a theoretical investigation of the potential for poly-Si PCDs to satisfy the count rate needs, while maintaining good energy resolution, of two CBCT applications-CBCT used for breast imaging and kilo-voltage CBCT used for providing localization information in image guided radiotherapy (referred to as BCT and kV-CBCT, respectively). The study focused on the performance of the critical first component of a PCD pixel circuit, the amplifier, under conditions relevant to the two applications. The study determined that, compared to the average input fluxes associated with BCT and kV-CBCT, a promising amplifier design employing poly-Si thin-film transistors can provide count rates two and four times in excess of those levels, respectively, assuming a dead time loss of 10%. In addition, calculational estimates based on foreseeable poly-Si circuit densities suggest that it should be possible to include sufficient circuitry to support 2 and 3 energy thresholds per pixel, respectively. Finally, prospects for further improvements are discussed.
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Affiliation(s)
- Albert K Liang
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, United States of America
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Ghazi P. A fluence modulation and scatter shielding apparatus for dedicated breast CT: Theory of operation. Med Phys 2020; 47:1590-1608. [PMID: 31955431 DOI: 10.1002/mp.14026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 01/12/2023] Open
Abstract
PURPOSE To introduce an auxiliary apparatus of fluence modulation and scatter shielding for dedicated breast computed tomography (bCT) and the corresponding patient-specific method of image acquisition. METHODS The apparatus is composed of two assemblies, referred to herein as the "Dynamic Fluence Gate" (FG) and "Scatter Shield" (SS), that work in synchrony to form a narrow beam sweeping the entire fan angle coverage of the imaging system during a projection. The apparatus, as a whole, is referred to as FG-SS. FG and SS are pre-patient and post-patient units, respectively. Each is composed of a rotating drum, on top of which are installed two sheets of high x-ray attenuating material, a sensory system, and the constituent robotics. The sheets of each unit are positioned such that an opening - a window Fluence Modulation and Scatter Shielding is formed between them. The rotations of the drums and positioning of the sheets are synchronized and adjusted such that a line of sight is created between the source, FG window, the breast, and the SS window. With line of sight achieved, the narrow beam transitions from the source to the detector. The fluence of the narrow beam during a projection depends on the size, shape, and positioning of the breast. The FG-SS method of imaging is discussed mathematically and demonstrated using computer simulations. A series of Monte Carlo simulations are conducted to evaluate the performance of the system as relates to its impact on the imager's dynamic range, dose distribution to the breast, noise inhomogeneity in reconstructed images, and scatter buildup in projections within small, medium, and large breasts composed of homogeneous medium breast tissue. RESULTS Implementation of FG-SS results in near scatter-free projections, reduction in both dose and the required dynamic range of the imager, and equalization of the quantum noise distribution in the reconstructed image. Using the disclosed design, the dynamic range was reduced by factors ranging from 1.6 to 5.5 across the range of breast sizes studied. A reduction in the acquisition of the scattered rays, varying between the factors of 6.1 (in the small breast) and 9.8 (in that large breast) was achieved and consequently, shading artifacts were suppressed. Noise in the CT image was equalized by reducing the overall spatial variation from 29% to <5% in small breast and from 45% to 14% in the large breast. An overall reduction in deposited dose to the breast was achieved - between 26% and 39% depending on the breast size. CONCLUSIONS Utilization of the FG-SS apparatus and technique was demonstrated via simulations to result in: significant reductions in dose to the breast, reductions in scatter uptake in projections, reduced required dynamic range of the imager, and homogenizing of quantum noise throughout the reconstructed image.
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Vedantham S, Tseng HW, Konate S, Shi L, Karellas A. Dedicated cone-beam breast CT using laterally-shifted detector geometry: Quantitative analysis of feasibility for clinical translation. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2020; 28:405-426. [PMID: 32333575 PMCID: PMC7347391 DOI: 10.3233/xst-200651] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
BACKGROUND High-resolution, low-noise detectors with minimal dead-space at chest-wall could improve posterior coverage and microcalcification visibility in the dedicated cone-beam breast CT (CBBCT). However, the smaller field-of-view necessitates laterally-shifted detector geometry to enable optimizing the air-gap for x-ray scatter rejection. OBJECTIVE To evaluate laterally-shifted detector geometry for CBBCT with clinical projection datasets that provide for anatomical structures and lesions. METHODS CBBCT projection datasets (n = 17 breasts) acquired with a 40×30 cm detector (1024×768-pixels, 0.388-mm pixels) were truncated along the fan-angle to emulate 20.3×30 cm, 22.2×30 cm and 24.1×30 cm detector formats and correspond to 20, 120, 220 pixels overlap in conjugate views, respectively. Feldkamp-Davis-Kress (FDK) algorithm with 3 different weighting schemes were used for reconstruction. Visual analysis for artifacts and quantitative analysis of root-mean-squared-error (RMSE), absolute difference between truncated and 40×30 cm reconstructions (Diff), and its power spectrum (PSDiff) were performed. RESULTS Artifacts were observed for 20.3×30 cm, but not for other formats. The 24.1×30 cm provided the best quantitative results with RMSE and Diff (both in units of μ, cm-1) of 4.39×10-3±1.98×10-3 and 4.95×10-4±1.34×10-4, respectively. The PSDiff (>0.3 cycles/mm) was in the order of 10-14μ2mm3 and was spatial-frequency independent. CONCLUSIONS Laterally-shifted detector CBBCT with at least 220 pixels overlap in conjugate views (24.1×30 cm detector format) provides quantitatively accurate and artifact-free image reconstruction.
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Affiliation(s)
- Srinivasan Vedantham
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ 85724
| | - Hsin-Wu Tseng
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724
| | - Souleymane Konate
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA 02115
| | - Linxi Shi
- Department of Radiology, Stanford University, Stanford, CA 94305
| | - Andrew Karellas
- Department of Medical Imaging, University of Arizona, Tucson, AZ 85724
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Siewerdsen JH, Uneri A, Hernandez AM, Burkett GW, Boone JM. Cone‐beam CT dose and imaging performance evaluation with a modular, multipurpose phantom. Med Phys 2019; 47:467-479. [DOI: 10.1002/mp.13952] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 11/18/2019] [Accepted: 11/23/2019] [Indexed: 12/17/2022] Open
Affiliation(s)
- J. H. Siewerdsen
- Department of Biomedical Engineering Johns Hopkins University Baltimore MD 21205USA
| | - A. Uneri
- Department of Biomedical Engineering Johns Hopkins University Baltimore MD 21205USA
| | - A. M. Hernandez
- Department of Radiology University of California – Davis Sacramento CA 95817USA
| | - G. W. Burkett
- Department of Radiology University of California – Davis Sacramento CA 95817USA
| | - J. M. Boone
- Department of Radiology University of California – Davis Sacramento CA 95817USA
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Ghazi P, Hernandez AM, Abbey C, Yang K, Boone JM. Shading artifact correction in breast CT using an interleaved deep learning segmentation and maximum-likelihood polynomial fitting approach. Med Phys 2019; 46:3414-3430. [PMID: 31102462 DOI: 10.1002/mp.13599] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 05/09/2019] [Accepted: 05/12/2019] [Indexed: 12/19/2022] Open
Abstract
PURPOSE The purpose of this work was twofold: (a) To provide a robust and accurate method for image segmentation of dedicated breast CT (bCT) volume data sets, and (b) to improve Hounsfield unit (HU) accuracy in bCT by means of a postprocessing method that uses the segmented images to correct for the low-frequency shading artifacts in reconstructed images. METHODS A sequential and iterative application of image segmentation and low-order polynomial fitting to bCT volume data sets was used in the interleaved correction (IC) method. Image segmentation was performed through a deep convolutional neural network (CNN) with a modified U-Net architecture. A total of 45 621 coronal bCT images from 111 patient volume data sets were segmented (using a previously published segmentation algorithm) and used for neural network training, validation, and testing. All patient data sets were selected from scans performed on four different prototype breast CT systems. The adipose voxels for each patient volume data set, segmented using the proposed CNN, were then fit to a three-dimensional low-order polynomial. The polynomial fit was subsequently used to correct for the shading artifacts introduced by scatter and beam hardening in a method termed "flat fielding." An interleaved utilization of image segmentation and flat fielding was repeated until a convergence criterion was satisfied. Mathematical and physical phantom studies were conducted to evaluate the dependence of the proposed algorithm on breast size and the distribution of fibroglandular tissue. In addition, a subset of patient scans (not used in the CNN training, testing or validation) were used to investigate the accuracy of the IC method across different scanner designs and beam qualities. RESULTS The IC method resulted in an accurate classification of different tissue types with an average Dice similarity coefficient > 95%, precision > 97%, recall > 95%, and F1-score > 96% across all tissue types. The flat fielding correction of bCT images resulted in a significant reduction in either cupping or capping artifacts in both mathematical and physical phantom studies as measured by the integral nonuniformity metric with an average reduction of 71% for cupping and 30% for capping across different phantom sizes, and the Uniformity Index with an average reduction of 53% for cupping and 34% for capping. CONCLUSION The validation studies demonstrated that the IC method improves Hounsfield Units (HU) accuracy and effectively corrects for shading artifacts caused by scatter contamination and beam hardening. The postprocessing approach described herein is relevant to the broad scope of bCT devices and does not require any modification in hardware or existing scan protocols. The trained CNN parameters and network architecture are available for interested users.
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Affiliation(s)
| | - Andrew M Hernandez
- Department of Radiology, University of California Davis, Sacramento, CA, 95817, USA
| | - Craig Abbey
- Department of Psychological & Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Kai Yang
- Department of Radiology, Massachusetts General Hospital, Boston, MA, 2114, USA
| | - John M Boone
- Department of Radiology, University of California Davis, Sacramento, CA, 95817, USA
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Caballo M, Boone JM, Mann R, Sechopoulos I. An unsupervised automatic segmentation algorithm for breast tissue classification of dedicated breast computed tomography images. Med Phys 2018; 45:2542-2559. [PMID: 29676025 PMCID: PMC5997547 DOI: 10.1002/mp.12920] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 02/27/2018] [Accepted: 04/04/2018] [Indexed: 01/30/2023] Open
Abstract
PURPOSE To develop and evaluate a new automatic classification algorithm to identify voxels containing skin, vasculature, adipose, and fibroglandular tissue in dedicated breast CT images. METHODS The proposed algorithm combines intensity- and region-based segmentation methods with energy minimizing splines and unsupervised data mining approaches for classifying and segmenting the different tissue types. Breast skin segmentation is achieved by a region-growing method which uses constraints from the previously extracted skin centerline to add robustness to the model and to reduce the false positive rate. An energy minimizing active contour model is then used to classify adipose tissue voxels by including gradient flow and region-based features. Finally, blood vessels are separated from fibroglandular tissue by a k-means clustering algorithm based on automatically extracted shape-based features. To evaluate the accuracy of the algorithm, two sets of 15 different patient breast CT scans, each acquired with different breast CT systems and acquisition settings were obtained. Three slices from each scan were manually segmented under the supervision of an experienced breast radiologist and considered the gold standard. Comparisons with manual segmentation were quantified using five similarity metrics: Dice similarity coefficient (DSC), sensitivity, conformity coefficient, and two Hausdorff distance measures. To evaluate the robustness to image noise, the segmentation was repeated after separately adding Gaussian noise with increasing standard deviation (in four steps, from 0.01 to 0.04) to an additional 15 slices from the first dataset. In addition, to evaluate vasculature classification, three different pre- and postcontrast injection patient breast CT images were classified and compared. Finally, DSC was also used for quantitative comparisons with previously proposed approaches for breast CT tissue classification using 10 images from the first dataset. RESULTS The algorithm showed a high accuracy in classifying the different tissue types for both breast CT systems, with an average DSC of 95% and 90% for the first and second image dataset, respectively. Furthermore, it demonstrated to be robust to image noise with a robustness to image noise of 85%, 83%, 79%, and 71% for the images corrupted with the four increasing noise levels. Previous methods for breast tissues classification resulted, for the tested dataset, in an average global DSC of 87%, while our approach resulted in a global average DSC of 94.5%. CONCLUSIONS The proposed algorithm resulted in accurate and robust breast tissue classification, with no prior training or threshold setting. Potential applications include breast density quantification and tissue pattern characterization (both biomarkers of cancer development), simulation-based radiation dose analysis, and patient data-based phantom design, which could be used for further breast imaging research.
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Affiliation(s)
- Marco Caballo
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - John M Boone
- Department of Radiology and Biomedical Engineering, University of California Davis Health, 4860 "Y" street, suite 3100 Ellison building, Sacramento, CA, 95817, USA
| | - Ritse Mann
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Ioannis Sechopoulos
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.,Dutch Expert Center for Screening (LRCB), PO Box 6873, 6503 GJ, Nijmegen, The Netherlands
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Raylman RR, Van Kampen W, Stolin AV, Gong W, Jaliparthi G, Martone PF, Smith MF, Sarment D, Clinthorne NH, Perna M. A dedicated breast-PET/CT scanner: Evaluation of basic performance characteristics. Med Phys 2018; 45:1603-1613. [PMID: 29389017 DOI: 10.1002/mp.12780] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 01/05/2018] [Accepted: 01/05/2018] [Indexed: 12/29/2022] Open
Abstract
PURPOSE Application of advanced imaging techniques, such as PET and x ray CT, can potentially improve detection of breast cancer. Unfortunately, both modalities have challenges in the detection of some lesions. The combination of the two techniques, however, could potentially lead to an overall improvement in diagnostic breast imaging. The purpose of this investigation is to test the basic performance of a new dedicated breast-PET/CT. METHODS The PET component consists of a rotating pair of detectors. Its performance was evaluated using the NEMA NU4-2008 protocols. The CT component utilizes a pulsed x ray source and flat panel detector mounted on the same gantry as the PET scanner. Its performance was assessed using specialized phantoms. The radiation dose to a breast during CT imaging was explored by the measurement of free-in-air kerma and air kerma measured at the center of a 16 cm-diameter PMMA cylinder. Finally, the combined capabilities of the system were demonstrated by imaging of a micro-hot-rod phantom. RESULTS Overall, performance of the PET component is comparable to many pre-clinical and other dedicated breast-PET scanners. Its spatial resolution is 2.2 mm, 5 mm from the center of the scanner using images created with the single-sliced-filtered-backprojection algorithm. Peak NECR is 24.6 kcps; peak sensitivity is 1.36%; the scatter fraction is 27%. Spatial resolution of the CT scanner is 1.1 lp/mm at 10% MTF. The free-in-air kerma is 2.33 mGy, while the PMMA-air kerma is 1.24 mGy. Finally, combined imaging of a micro-hot-rod phantom illustrated the potential utility of the dual-modality images produced by the system. CONCLUSION The basic performance characteristics of a new dedicated breast-PET/CT scanner are good, demonstrating that its performance is similar to current dedicated PET and CT scanners. The potential value of this system is the capability to produce combined duality-modality images that could improve detection of breast disease. The next stage in development of this system is testing with more advanced phantoms and human subjects.
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Affiliation(s)
- Raymond R Raylman
- Center for Advanced Imaging, Department of Radiology, 1 Medical Center Dr., West Virginia University, Morgantown, WV, 26506, USA
| | - Will Van Kampen
- Xoran Technologies Inc., 5210 S State Rd., Ann Arbor, MI, 48108, USA
| | - Alexander V Stolin
- Center for Advanced Imaging, Department of Radiology, 1 Medical Center Dr., West Virginia University, Morgantown, WV, 26506, USA
| | - Wenbo Gong
- Xoran Technologies Inc., 5210 S State Rd., Ann Arbor, MI, 48108, USA
| | - Gangadhar Jaliparthi
- Center for Advanced Imaging, Department of Radiology, 1 Medical Center Dr., West Virginia University, Morgantown, WV, 26506, USA
| | - Peter F Martone
- Center for Advanced Imaging, Department of Radiology, 1 Medical Center Dr., West Virginia University, Morgantown, WV, 26506, USA
| | - Mark F Smith
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, MD, 21201, USA
| | - David Sarment
- Xoran Technologies Inc., 5210 S State Rd., Ann Arbor, MI, 48108, USA
| | | | - Mark Perna
- Perna Health Physics, Inc., 705 Augusta Dr, Bridgeville, PA, 15017, USA
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Shi L, Vedantham S, Karellas A, Zhu L. The role of off-focus radiation in scatter correction for dedicated cone beam breast CT. Med Phys 2017; 45:191-201. [PMID: 29159941 DOI: 10.1002/mp.12686] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 11/02/2017] [Accepted: 11/12/2017] [Indexed: 12/18/2022] Open
Abstract
PURPOSE Dedicated cone beam breast CT (CBBCT) suffers from x-ray scatter contamination. We aim to identify the source of the significant difference between the scatter distributions estimated by two recent methods proposed by our group and to investigate its effect on CBBCT image quality. METHOD We recently proposed two novel methods of scatter correction for CBBCT, using a library based (LB) technique and a forward projection (FP) model. Despite similar enhancement on CBBCT image qualities, these two methods obtain very different scatter distributions. We hypothesize that the off-focus radiation (OFR) is the contributor and results in nontrivial signals in x-ray projections, which is ignored in the scatter estimation via the LB method. Experiments using a thin wire test tool are designed to study the effect of OFR on CBBCT spatial resolution by measuring the point spread function (PSF) and the modulation transfer function (MTF). A narrow collimator setting is used to suppress the OFR-induced signals. In addition, "PSFs" and "MTFs" are measured on clinical CBBCT images obtained by the LB and FP methods using small calcifications as point sources. The improvement of spatial resolution achieved by suppressing OFR in the wire experiment as well as in the clinical study is quantified by the improvement ratios of PSFs and spatial frequencies at different MTF values. Our hypothesis that OFR causes the imaging difference between the FP and LB methods is verified if these ratios obtained from experimental and clinical data are consistent. RESULTS In the wire experiment, the results show that suppression of OFR increases the maximum signal of the PSF by about 14% and reduces the full-width-at-half-maximum (FWHM) by about 12.0%. Similar improvement on spatial resolution is achieved by the FP method compared with the LB method in the patient study. The improvement ratios of spatial frequencies at different MTF values without OFR match very well in both studies at a level of around 16%, with an average root-mean-square difference of 0.47%. CONCLUSION The results of the wire experiment and the clinical study indicate that the main difference between the LB and FP methods is whether the OFR-induced signals are included after scatter correction. Our study further shows that OFR significantly affects the image spatial resolution of CBBCT, indicating that the visualization of micro-calcifications is susceptible to OFR contamination. Our finding is therefore important in further improvement of diagnostic performance of CBBCT.
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Affiliation(s)
- Linxi Shi
- Nuclear and Radiological Engineering and Medical Physics Programs, The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA.,Department of Radiology, Stanford University, Palo Alto, CA, 94305, USA
| | - Srinivasan Vedantham
- Department of Medical Imaging, University of Arizona College of Medicine, Tucson, AZ, 85724, USA.,Banner University Medical Center, Tucson, AZ, 85724, USA
| | - Andrew Karellas
- Department of Medical Imaging, University of Arizona College of Medicine, Tucson, AZ, 85724, USA.,Banner University Medical Center, Tucson, AZ, 85724, USA
| | - Lei Zhu
- Nuclear and Radiological Engineering and Medical Physics Programs, The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA.,Department of Modern Physics, School of Physical Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, China
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Cao Q, Sisniega A, Brehler M, Stayman JW, Yorkston J, Siewerdsen JH, Zbijewski W. Modeling and evaluation of a high-resolution CMOS detector for cone-beam CT of the extremities. Med Phys 2017; 45:114-130. [PMID: 29095489 DOI: 10.1002/mp.12654] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 10/19/2017] [Accepted: 10/23/2017] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Quantitative assessment of trabecular bone microarchitecture in extremity cone-beam CT (CBCT) would benefit from the high spatial resolution, low electronic noise, and fast scan time provided by complementary metal-oxide semiconductor (CMOS) x-ray detectors. We investigate the performance of CMOS sensors in extremity CBCT, in particular with respect to potential advantages of thin (<0.7 mm) scintillators offering higher spatial resolution. METHODS A cascaded systems model of a CMOS x-ray detector incorporating the effects of CsI:Tl scintillator thickness was developed. Simulation studies were performed using nominal extremity CBCT acquisition protocols (90 kVp, 0.126 mAs/projection). A range of scintillator thickness (0.35-0.75 mm), pixel size (0.05-0.4 mm), focal spot size (0.05-0.7 mm), magnification (1.1-2.1), and dose (15-40 mGy) was considered. The detectability index was evaluated for both CMOS and a-Si:H flat-panel detector (FPD) configurations for a range of imaging tasks emphasizing spatial frequencies associated with feature size aobj. Experimental validation was performed on a CBCT test bench in the geometry of a compact orthopedic CBCT system (SAD = 43.1 cm, SDD = 56.0 cm, matching that of the Carestream OnSight 3D system). The test-bench studies involved a 0.3 mm focal spot x-ray source and two CMOS detectors (Dalsa Xineos-3030HR, 0.099 mm pixel pitch) - one with the standard CsI:Tl thickness of 0.7 mm (C700) and one with a custom 0.4 mm thick scintillator (C400). Measurements of modulation transfer function (MTF), detective quantum efficiency (DQE), and CBCT scans of a cadaveric knee (15 mGy) were obtained for each detector. RESULTS Optimal detectability for high-frequency tasks (feature size of ~0.06 mm, consistent with the size of trabeculae) was ~4× for the C700 CMOS detector compared to the a-Si:H FPD at nominal system geometry of extremity CBCT. This is due to ~5× lower electronic noise of a CMOS sensor, which enables input quantum-limited imaging at smaller pixel size. Optimal pixel size for high-frequency tasks was <0.1 mm for a CMOS, compared to ~0.14 mm for an a-Si:H FPD. For this fine pixel pitch, detectability of fine features could be improved by using a thinner scintillator to reduce light spread blur. A 22% increase in detectability of 0.06 mm features was found for the C400 configuration compared to C700. An improvement in the frequency at 50% modulation (f50 ) of MTF was measured, increasing from 1.8 lp/mm for C700 to 2.5 lp/mm for C400. The C400 configuration also achieved equivalent or better DQE as C700 for frequencies above ~2 mm-1 . Images of cadaver specimens confirmed improved visualization of trabeculae with the C400 sensor. CONCLUSIONS The small pixel size of CMOS detectors yields improved performance in high-resolution extremity CBCT compared to a-Si:H FPDs, particularly when coupled with a custom 0.4 mm thick scintillator. The results indicate that adoption of a CMOS detector in extremity CBCT can benefit applications in quantitative imaging of trabecular microstructure in humans.
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Affiliation(s)
- Qian Cao
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Alejandro Sisniega
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Michael Brehler
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - J Webster Stayman
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21205, USA
| | | | - Jeffrey H Siewerdsen
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21205, USA.,Russell H Morgan Department of Radiology, Johns Hopkins University, Baltimore, 21205, USA
| | - Wojciech Zbijewski
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21205, USA
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Jeon H, Youn H, Kim JS, Nam J, Lee J, Lee J, Park D, Kim W, Ki Y, Kim D. Generation of polychromatic projection for dedicated breast computed tomography simulation using anthropomorphic numerical phantom. PLoS One 2017; 12:e0187242. [PMID: 29108024 PMCID: PMC5673211 DOI: 10.1371/journal.pone.0187242] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 10/17/2017] [Indexed: 11/21/2022] Open
Abstract
Numerical simulations are fundamental to the development of medical imaging systems because they can save time and effort in research and development. In this study, we developed a method of creating the virtual projection images that are necessary to study dedicated breast computed tomography (BCT) systems. Anthropomorphic software breast phantoms of the conventional compression type were synthesized and redesigned to meet the requirements of dedicated BCT systems. The internal structure of the breast was randomly constructed to develop the proposed phantom, enabling the internal structure of a naturally distributed real breast to be simulated. When using the existing monochromatic photon incidence assumption for projection-image generation, it is not possible to simulate various artifacts caused by the X-ray spectrum, such as the beam hardening effect. Consequently, the system performance could be overestimated. Therefore, we considered the polychromatic spectrum in the projection image generation process and verified the results. The proposed method is expected to be useful for the development and optimization of BCT systems.
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Affiliation(s)
- Hosang Jeon
- Department of Radiation Oncology and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Gyeongsangnam-do, South Korea
| | - Hanbean Youn
- Department of Radiation Oncology and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Gyeongsangnam-do, South Korea
| | - Jin Sung Kim
- Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea
| | - Jiho Nam
- Department of Radiation Oncology and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Gyeongsangnam-do, South Korea
| | - Jayoung Lee
- Department of Radiation Oncology and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Gyeongsangnam-do, South Korea
| | - Juhye Lee
- Department of Radiation Oncology and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Gyeongsangnam-do, South Korea
| | - Dahl Park
- Department of Radiation Oncology, Pusan National University Hospital, Busan, South Korea
| | - Wontaek Kim
- Department of Radiation Oncology, Pusan National University Hospital, Busan, South Korea
| | - Yongkan Ki
- Department of Radiation Oncology, Pusan National University Hospital, Busan, South Korea
| | - Donghyun Kim
- Department of Radiation Oncology, Pusan National University Hospital, Busan, South Korea
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O'Connell AM, Karellas A, Vedantham S, Kawakyu-O'Connor DT. Newer Technologies in Breast Cancer Imaging: Dedicated Cone-Beam Breast Computed Tomography. Semin Ultrasound CT MR 2017; 39:106-113. [PMID: 29317032 DOI: 10.1053/j.sult.2017.09.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Dedicated breast computed tomography (CT) is the latest in a long history of breast imaging techniques dating back to the 1960s. Breast imaging is performed both for cancer screening as well as for diagnostic evaluation of symptomatic patients. Dedicated breast CT received US Food and Drug Administration approval for diagnostic use in 2015 and is slowly gaining recognition for its value in diagnostic 3-dimensional imaging of the breast, and also for injected contrast-enhanced imaging applications. Conventional mammography has known limitations in sensitivity and specificity, especially in dense breasts. Breast tomosynthesis was US Food and Drug Administration approved in 2011 and is now widely used. Dedicated breast CT is the next technological advance, combining real 3-dimensional imaging with the ease of contrast administration. The lack of painful compression and manipulation of the breasts also makes dedicated breast CT much more acceptable for the patients.
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Affiliation(s)
- Avice M O'Connell
- Department of Imaging Sciences, Section of Women's Imaging, University of Rochester Medical Center, Rochester, NY
| | - Andrew Karellas
- Department of Medical Imaging, Banner University Medical Center, University of Arizona College of Medicine, Tucson, AZ
| | - Srinivasan Vedantham
- Department of Medical Imaging (DMI), Office for Project Statistical and Design Support-DMI, Banner University Medical Center, University of Arizona College of Medicine, Tucson, AZ
| | - Daniel T Kawakyu-O'Connor
- Department of Imaging Sciences, Section of Emergency Imaging, University of Rochester Medical Center, Rochester, NY.
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Hernandez AM, Boone JM. Average glandular dose coefficients for pendant-geometry breast CT using realistic breast phantoms. Med Phys 2017; 44:5096-5105. [PMID: 28715130 DOI: 10.1002/mp.12477] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 06/06/2017] [Accepted: 06/26/2017] [Indexed: 02/01/2023] Open
Abstract
PURPOSE To design volume-specific breast phantoms from breast CT (bCT) data sets and estimate the associated normalized mean glandular dose coefficients for breast CT using Monte Carlo methods. METHODS A large cohort of bCT data sets (N = 215) was used to evaluate breast volume into quintiles (plus the top 5%). The average radius profile was then determined for each of the six volume-specific groups and used to both fabricate physical phantoms and generate mathematical phantoms (V1-V6; "V" denotes classification by volume). The MCNP6 Monte Carlo code was used to model a prototype bCT system fabricated at our institution; and this model was validated against physical measurements in the fabricated phantoms. The mathematical phantoms were used to simulate normalized mean glandular dose coefficients for both monoenergetic source photons "DgNCT (E)" (8-70 keV in 1 keV intervals) and polyenergetic x-ray beams "pDgNCT " (35-70 kV in 1 kV intervals). The Monte Carlo code was used to study the influence of breast size (V1 vs. V5) and glandular fraction (6.4% vs. 45.8%) on glandular dose. The pDgNCT coefficients estimated for the V1, V3, and V5 phantoms were also compared to those generated using simple, cylindrical phantoms with equivalent volume and two geometrical constraints including; (a) cylinder radius determined at the breast phantom chest wall "Rcw "; and (b) cylinder radius determined at the breast phantom center-of-mass "RCOM ". RESULTS Satisfactory agreement was observed for dose estimations using MCNP6 compared with both physical measurements in the V1, V3, and V5 phantoms (R2 = 0.995) and reference bCT dose coefficients using simple phantoms (R2 = 0.999). For a 49 kV spectrum with 1.5 mm Al filtration, differences in glandular fraction [6.5% (5th percentile) vs. 45.8% (95th percentile)] had a 13.2% influence on pDgNCT for the V3 phantom, and differences in breast size (V1 vs. V5) had a 16.6% influence on pDgNCT for a breast composed of 17% (median) fibroglandular tissue. For cylindrical phantoms with a radius of RCOM , the differences were 1.5%, 0.1%, and 2.1% compared with the V1, V3, and V5 phantoms, respectively. CONCLUSION Breast phantoms were designed using a large cohort of bCT data sets across a range of six breast sizes. These phantoms were then fabricated and used for the estimation of glandular dose in breast CT. The mathematical phantoms and associated glandular dose coefficients for a range of breast sizes (V1-V6) and glandular fractions (5th to 95th percentiles) are available for interested users.
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Affiliation(s)
- Andrew M Hernandez
- Department of Radiology, Biomedical Engineering Graduate Group, University of California Davis, Sacramento, CA, 95817, USA
| | - John M Boone
- Departments of Radiology and Biomedical Engineering, University of California Davis, Sacramento, CA, 95817, USA
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Shah JP, Mann SD, McKinley RL, Tornai MP. Implementation and CT sampling characterization of a third-generation SPECT-CT system for dedicated breast imaging. J Med Imaging (Bellingham) 2017; 4:033502. [PMID: 28924570 PMCID: PMC5536183 DOI: 10.1117/1.jmi.4.3.033502] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 07/14/2017] [Indexed: 11/14/2022] Open
Abstract
Stand-alone cone beam computed tomography (CT) and single-photon emission computed tomography (SPECT) systems capable of complex acquisition trajectories have previously been developed for breast imaging. Fully three-dimensional (3-D) motions of SPECT systems provide views into the chest wall and throughout the entire volume. The polar tilting capability of the CBCT system has shown improvement in sampling close to the chest wall, while eliminating cone beam artifacts. Here, a single hybrid SPECT-CT system, with each individual modality capable of independently traversing complex trajectories around a common pendant breast volume, was developed. We present the practical implementation of this design and preliminary results of the CT system. The fully 3-D SPECT was nested inside the suspended CT gantry and oriented perpendicular to the CT source-detector pair. Both subsystems were positioned on a rotation stage, with the combined polar and azimuthal motions enabling spherical trajectories. Six trajectories were used for initial evaluation of the tilt capable CT system. The developed system can achieve polar tilt angles with a [Formula: see text] positioning error and no hysteresis. Initial imaging results demonstrate that additional off-axis projection views of various geometric resolution phantoms facilitate more complete sampling, more consistent attenuation value recovery, and markedly improved reconstructions. This system could have various applications in diagnostic or therapeutic breast imaging.
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Affiliation(s)
- Jainil P. Shah
- Duke University, Department of Biomedical Engineering, Durham, North Carolina, United States
- Duke University Medical Center, Multi Modality Imaging Lab, Department of Radiology, Durham, North Carolina, United States
| | - Steve D. Mann
- Duke University Medical Center, Multi Modality Imaging Lab, Department of Radiology, Durham, North Carolina, United States
- Duke University Medical Center, Medical Physics Graduate Program, Durham, North Carolina, United States
| | | | - Martin P. Tornai
- Duke University, Department of Biomedical Engineering, Durham, North Carolina, United States
- Duke University Medical Center, Multi Modality Imaging Lab, Department of Radiology, Durham, North Carolina, United States
- Duke University Medical Center, Medical Physics Graduate Program, Durham, North Carolina, United States
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Ghani MU, Wong MD, Ren L, Wu D, Zheng B, Rong JX, Wu X, Liu H. Characterization of Continuous and Pulsed Emission modes of a Hybrid Micro Focus X-ray Source for Medical Imaging Applications. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH. SECTION A, ACCELERATORS, SPECTROMETERS, DETECTORS AND ASSOCIATED EQUIPMENT 2017; 853:70-77. [PMID: 28959083 PMCID: PMC5612449 DOI: 10.1016/j.nima.2017.02.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The aim of this study was to quantitatively characterize a micro focus x-ray tube that can operate in both continuous and pulsed emission modes. The micro focus x-ray source (Model L9181-06, Hamamatsu Photonics, Japan) has a varying focal spot size ranging from 16-50 μm as the source output power changes from 10-39 W. We measured the source output, beam quality, focal spot sizes, kV accuracy, spectra shapes and spatial resolution. Source output was measured using an ionization chamber for various tube voltages (kVs) with varying current (μA) and distances. The beam quality was measured in terms of half value layer (HVL), kV accuracy was measured with a non-invasive kV meter, and the spectra was measured using a compact integrated spectrometer system. The focal spot sizes were measured using a slit method with a CCD detector with a pixel pitch of 22 μm. The spatial resolution was quantitatively measured using the slit method with a CMOS flat panel detector with a 50 μm pixel pitch, and compared to the qualitative results obtained by imaging a contrast bar pattern. The focal spot sizes in the vertical direction were smaller than that of the horizontal direction, the impact of which was visible when comparing the spatial resolution values. Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam quality, spectra shape and spatial resolution effects. There were no significantly large differences, thus providing the motivation for future studies to design and develop stable and robust cone beam imaging systems for various diagnostic applications.
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Affiliation(s)
- Muhammad U. Ghani
- Center for Biomedical Engineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, 73019, USA
| | - Molly D. Wong
- Center for Biomedical Engineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, 73019, USA
| | - Liqiang Ren
- Center for Biomedical Engineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, 73019, USA
| | - Di Wu
- Center for Biomedical Engineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, 73019, USA
| | - Bin Zheng
- Center for Biomedical Engineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, 73019, USA
| | - John X. Rong
- Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Xizeng Wu
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, 35249, USA
| | - Hong Liu
- Center for Biomedical Engineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, 73019, USA
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40
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Cone-beam micro computed tomography dedicated to the breast. Med Eng Phys 2016; 38:1449-1457. [DOI: 10.1016/j.medengphy.2016.09.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 08/23/2016] [Accepted: 09/23/2016] [Indexed: 11/23/2022]
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Douglas DB, Petricoin EF, Liotta L, Wilson E. D3D augmented reality imaging system: proof of concept in mammography. MEDICAL DEVICES-EVIDENCE AND RESEARCH 2016; 9:277-83. [PMID: 27563261 PMCID: PMC4984822 DOI: 10.2147/mder.s110756] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Purpose The purpose of this article is to present images from simulated breast microcalcifications and assess the pattern of the microcalcifications with a technical development called “depth 3-dimensional (D3D) augmented reality”. Materials and methods A computer, head display unit, joystick, D3D augmented reality software, and an in-house script of simulated data of breast microcalcifications in a ductal distribution were used. No patient data was used and no statistical analysis was performed. Results The D3D augmented reality system demonstrated stereoscopic depth perception by presenting a unique image to each eye, focal point convergence, head position tracking, 3D cursor, and joystick fly-through. Conclusion The D3D augmented reality imaging system offers image viewing with depth perception and focal point convergence. The D3D augmented reality system should be tested to determine its utility in clinical practice.
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Affiliation(s)
| | - Emanuel F Petricoin
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA
| | - Lance Liotta
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA
| | - Eugene Wilson
- Department of Radiology, Fort Benning, Columbus, GA, USA
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Jang SY, Kim HK, Youn H, Cho S, Cunningham IA. Fourier Analysis of Noise Characteristics in Cone-Beam Microtomography Laboratory Scanners. IEEE Trans Biomed Eng 2016; 64:173-183. [PMID: 27093307 DOI: 10.1109/tbme.2016.2552496] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
GOAL We investigate the signal and noise performance of an x-ray microtomography system that incorporates a complementary metal-oxide-semiconductor flat-panel detector as a projection image receptor. METHODS Signal and noise performance is analyzed in the Fourier domain using modulation-transfer function (MTF), noise-power spectrum (NPS), and noise-equivalent number of quanta (NEQ) with respect to magnification and different convolution kernels for image reconstruction. RESULTS Higher magnification provides lower NPS, and thus, higher NEQ performance in the transaxial planes from microtomography. A window function capable of smoothing the ramp filter edge to below one-half of the Nyquist limit results in better performance in terms of NPS and NEQ. The characteristics of convolution kernels do not affect signal and noise performance in longitudinal planes; hence, MTF performance mainly dominates the NEQ performance. The signal and noise performances investigated in this study are demonstrated with images obtained from the contrast phantom and postmortem mouse. CONCLUSION The results of our study could be helpful in developing x-ray microtomography systems based on flat-panel detectors.
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Douglas DB, Boone JM, Petricoin E, Liotta L, Wilson E. Augmented Reality Imaging System: 3D Viewing of a Breast Cancer. JOURNAL OF NATURE AND SCIENCE 2016; 2:e215. [PMID: 27774517 PMCID: PMC5074083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
OBJECTIVE To display images of breast cancer from a dedicated breast CT using Depth 3-Dimensional (D3D) augmented reality. METHODS A case of breast cancer imaged using contrast-enhanced breast CT (Computed Tomography) was viewed with the augmented reality imaging, which uses a head display unit (HDU) and joystick control interface. RESULTS The augmented reality system demonstrated 3D viewing of the breast mass with head position tracking, stereoscopic depth perception, focal point convergence and the use of a 3D cursor and joy-stick enabled fly through with visualization of the spiculations extending from the breast cancer. CONCLUSION The augmented reality system provided 3D visualization of the breast cancer with depth perception and visualization of the mass's spiculations. The augmented reality system should be further researched to determine the utility in clinical practice.
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Affiliation(s)
- David B. Douglas
- Department of Radiology, Stanford University, Palo Alto, CA, USA
| | - John M. Boone
- Department of Radiology, University of California, Davis, CA, USA
| | - Emanuel Petricoin
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA, USA
| | - Lance Liotta
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA, USA
| | - Eugene Wilson
- Department of Radiology, Fort Benning, Columbus, GA, USA
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Ferrero A, Peng Q, Burkett GW, Sumanasena B, Moses WW, Badawi RD. Preliminary performance characterization of DbPET2.1, a PET scanner dedicated to the imaging of the breast and extremities. Biomed Phys Eng Express 2015; 1. [PMID: 31798968 DOI: 10.1088/2057-1976/1/1/015202] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The combined effort of several laboratories at our institution resulted in the building of the first high resolution PET/CT prototype dedicated to imaging the body extremities. Ongoing clinical trials for breast cancer diagnosis and assessment of response to treatment underlined the need for a second generation prototype with improved electronics and spatial resolution. A preliminary version has been assembled and fully characterized. In this work we present further improvements in the detector performance as well as the readout electronics for the PET component. The detector consists of a 16×16 array of 1.27×1.27×20mm3 LYSO crystals, the smallest crystal size for completed breast PET prototypes to date, directly coupled to a position-sensitive photomultiplier tube (PSPMT). The scintillator crystals are polished on all 6 faces and separated by ~70 μm ESR reflector. The readout electronics were redesigned to reduce their footprint and improve timing resolution. We report a detector energy and timing resolution of 12% and 1.0 ns, respectively, and an average intrinsic spatial resolution of 1.29 mm (central row in one detector array). The new PET/CT has been fully assembled and initial system characterization is being perfomed. We report a system energy resolution of 15.7%, a timing resolution of 1.5 ns and an FBP image spatial resolution in the center of the FOV of 1.6 mm.
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Affiliation(s)
- Andrea Ferrero
- Biomedical Engineering Graduate Group, UC Davis, CA, USA
| | - Qiyu Peng
- Lawrence Berkeley National Lab, Berkeley, CA, USA
| | - George W Burkett
- Department of Radiology, UC Davis Medical Center, Sacramento, CA, USA
| | | | | | - Ramsey D Badawi
- Biomedical Engineering Graduate Group, UC Davis, CA, USA.,Department of Radiology, UC Davis Medical Center, Sacramento, CA, USA
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