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Fajardo LL, Hillis SL, Zheng B, Wong MD, Ghani MU, Omoumi FH, Li Y, Jenkins P, Peterson ME, Wu X, Liu H. A Pilot Study to Assess the Performance of Phase-Sensitive Breast Tomosynthesis. Radiology 2023; 306:e213198. [PMID: 36165790 PMCID: PMC9885338 DOI: 10.1148/radiol.213198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 07/22/2022] [Accepted: 08/09/2022] [Indexed: 01/26/2023]
Abstract
Background A new modality, phase-sensitive breast tomosynthesis (PBT), may have similar diagnostic performance to conventional breast tomosynthesis but with a reduced radiation dose. Purpose To perform a pilot study of the performance of a novel PBT system compared with conventional digital breast tomosynthesis (DBT) in patients undergoing additional diagnostic imaging workup for breast lesions. Materials and Methods In a prospective study from June 2020 to March 2021, participants with suspicious breast lesions detected at screening DBT or MRI were recruited for additional PBT imaging before additional diagnostic workup or biopsy. In this pilot study, nine radiologists independently evaluated image quality and assessed the likelihood of lesion malignancy by retrospectively evaluating DBT and PBT images in two separate reading sessions. Image quality was rated subjectively using a Likert scale from 1 to 5. Areas under the receiver operating characteristic curve (AUCs) were used to compare the lesion classification (malignant vs benign) performance of the radiologists. Results Images in 50 patients (mean age, 56 years ± 12 [SD]; 49 women) with 52 evaluable lesions (28 malignant) were assessed. For image appearance and general feature visibility, DBT images had a higher total mean image quality score (3.8) than PBT images (2.9), with P < .002 for each comparison. For classification of lesions as benign or malignant, the AUCs were 0.74 for both PBT and DBT. PBT images were acquired at a 24% mean radiation dose reduction (mean, 1.78 mGy vs 2.34 mGy for DBT; P < .001). Conclusion The phase-sensitive breast tomosynthesis system had a 24% lower mean radiation dose compared with digital breast tomosynthesis, although with lower image quality. Diagnostic performance of the system remains to be determined in larger studies. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Gao and Moy in this issue.
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Affiliation(s)
- Laurie L. Fajardo
- From the Department of Radiology and Imaging Sciences, University of
Utah, Salt Lake City, Utah (L.L.F., P.J., M.E.P.); Departments of Radiology and
Biostatistics, University of Iowa, Iowa City, Iowa (S.L.H.); Advanced Medical
Imaging Center and School of Electrical and Computer Engineering, University of
Oklahoma, Norman, OK 73019 (B.Z., M.D.W., M.U.G., F.H.O., Y.L., H.L.); and
Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala
(X.W.)
| | - Stephen L. Hillis
- From the Department of Radiology and Imaging Sciences, University of
Utah, Salt Lake City, Utah (L.L.F., P.J., M.E.P.); Departments of Radiology and
Biostatistics, University of Iowa, Iowa City, Iowa (S.L.H.); Advanced Medical
Imaging Center and School of Electrical and Computer Engineering, University of
Oklahoma, Norman, OK 73019 (B.Z., M.D.W., M.U.G., F.H.O., Y.L., H.L.); and
Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala
(X.W.)
| | - Bin Zheng
- From the Department of Radiology and Imaging Sciences, University of
Utah, Salt Lake City, Utah (L.L.F., P.J., M.E.P.); Departments of Radiology and
Biostatistics, University of Iowa, Iowa City, Iowa (S.L.H.); Advanced Medical
Imaging Center and School of Electrical and Computer Engineering, University of
Oklahoma, Norman, OK 73019 (B.Z., M.D.W., M.U.G., F.H.O., Y.L., H.L.); and
Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala
(X.W.)
| | - Molly Donovan Wong
- From the Department of Radiology and Imaging Sciences, University of
Utah, Salt Lake City, Utah (L.L.F., P.J., M.E.P.); Departments of Radiology and
Biostatistics, University of Iowa, Iowa City, Iowa (S.L.H.); Advanced Medical
Imaging Center and School of Electrical and Computer Engineering, University of
Oklahoma, Norman, OK 73019 (B.Z., M.D.W., M.U.G., F.H.O., Y.L., H.L.); and
Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala
(X.W.)
| | - Muhammad U. Ghani
- From the Department of Radiology and Imaging Sciences, University of
Utah, Salt Lake City, Utah (L.L.F., P.J., M.E.P.); Departments of Radiology and
Biostatistics, University of Iowa, Iowa City, Iowa (S.L.H.); Advanced Medical
Imaging Center and School of Electrical and Computer Engineering, University of
Oklahoma, Norman, OK 73019 (B.Z., M.D.W., M.U.G., F.H.O., Y.L., H.L.); and
Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala
(X.W.)
| | - Farid H. Omoumi
- From the Department of Radiology and Imaging Sciences, University of
Utah, Salt Lake City, Utah (L.L.F., P.J., M.E.P.); Departments of Radiology and
Biostatistics, University of Iowa, Iowa City, Iowa (S.L.H.); Advanced Medical
Imaging Center and School of Electrical and Computer Engineering, University of
Oklahoma, Norman, OK 73019 (B.Z., M.D.W., M.U.G., F.H.O., Y.L., H.L.); and
Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala
(X.W.)
| | - Yuhua Li
- From the Department of Radiology and Imaging Sciences, University of
Utah, Salt Lake City, Utah (L.L.F., P.J., M.E.P.); Departments of Radiology and
Biostatistics, University of Iowa, Iowa City, Iowa (S.L.H.); Advanced Medical
Imaging Center and School of Electrical and Computer Engineering, University of
Oklahoma, Norman, OK 73019 (B.Z., M.D.W., M.U.G., F.H.O., Y.L., H.L.); and
Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala
(X.W.)
| | - Peter Jenkins
- From the Department of Radiology and Imaging Sciences, University of
Utah, Salt Lake City, Utah (L.L.F., P.J., M.E.P.); Departments of Radiology and
Biostatistics, University of Iowa, Iowa City, Iowa (S.L.H.); Advanced Medical
Imaging Center and School of Electrical and Computer Engineering, University of
Oklahoma, Norman, OK 73019 (B.Z., M.D.W., M.U.G., F.H.O., Y.L., H.L.); and
Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala
(X.W.)
| | - Michael E. Peterson
- From the Department of Radiology and Imaging Sciences, University of
Utah, Salt Lake City, Utah (L.L.F., P.J., M.E.P.); Departments of Radiology and
Biostatistics, University of Iowa, Iowa City, Iowa (S.L.H.); Advanced Medical
Imaging Center and School of Electrical and Computer Engineering, University of
Oklahoma, Norman, OK 73019 (B.Z., M.D.W., M.U.G., F.H.O., Y.L., H.L.); and
Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala
(X.W.)
| | - Xizeng Wu
- From the Department of Radiology and Imaging Sciences, University of
Utah, Salt Lake City, Utah (L.L.F., P.J., M.E.P.); Departments of Radiology and
Biostatistics, University of Iowa, Iowa City, Iowa (S.L.H.); Advanced Medical
Imaging Center and School of Electrical and Computer Engineering, University of
Oklahoma, Norman, OK 73019 (B.Z., M.D.W., M.U.G., F.H.O., Y.L., H.L.); and
Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala
(X.W.)
| | - Hong Liu
- From the Department of Radiology and Imaging Sciences, University of
Utah, Salt Lake City, Utah (L.L.F., P.J., M.E.P.); Departments of Radiology and
Biostatistics, University of Iowa, Iowa City, Iowa (S.L.H.); Advanced Medical
Imaging Center and School of Electrical and Computer Engineering, University of
Oklahoma, Norman, OK 73019 (B.Z., M.D.W., M.U.G., F.H.O., Y.L., H.L.); and
Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala
(X.W.)
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Ghani MU, Omoumi FH, Wu X, Fajardo LL, Zheng B, Liu H. Evaluation and comparison of a CdTe based photon counting detector with an energy integrating detector for X-ray phase sensitive imaging of breast cancer. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2022; 30:207-219. [PMID: 34957945 DOI: 10.3233/xst-211028] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
PURPOSE To compare imaging performance of a cadmium telluride (CdTe) based photon counting detector (PCD) with a CMOS based energy integrating detector (EID) for potential phase sensitive imaging of breast cancer. METHODS A high energy inline phase sensitive imaging prototype consisting of a microfocus X-ray source with geometric magnification of 2 was employed. The pixel pitch of the PCD was 55μm, while 50μm for EID. The spatial resolution was quantitatively and qualitatively assessed through modulation transfer function (MTF) and bar pattern images. The edge enhancement visibility was assessed by measuring edge enhancement index (EEI) using the acrylic edge acquired images. A contrast detail (CD) phantom was utilized to compare detectability of simulated tumors, while an American College of Radiology (ACR) accredited phantom for mammography was used to compare detection of simulated calcification clusters. A custom-built phantom was employed to compare detection of fibrous structures. The PCD images were acquired at equal, and 30% less mean glandular dose (MGD) levels as of EID images. Observer studies along with contrast to noise ratio (CNR) and signal to noise ratio (SNR) analyses were performed for comparison of two detection systems. RESULTS MTF curves and bar pattern images revealed an improvement of about 40% in the cutoff resolution with the PCD. The excellent spatial resolution offered by PCD system complemented superior detection of the diffraction fringes at boundaries of the acrylic edge and resulted in an EEI value of 3.64 as compared to 1.44 produced with EID image. At equal MGD levels (standard dose), observer studies along with CNR and SNR analyses revealed a substantial improvement of PCD acquired images in detection of simulated tumors, calcification clusters, and fibrous structures. At 30% less MGD, PCD images preserved image quality to yield equivalent (slightly better) detection as compared to the standard dose EID images. CONCLUSION CdTe-based PCDs are technically feasible to image breast abnormalities (low/high contrast structures) at low radiation dose levels using the high energy inline phase sensitive imaging technique.
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Affiliation(s)
- Muhammad U Ghani
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, USA
| | - Farid H Omoumi
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, USA
| | - Xizeng Wu
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Laurie L Fajardo
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA
| | - Bin Zheng
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, USA
| | - Hong Liu
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, USA
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Ghani MU, Gregory B, Omoumi F, Zheng B, Yan A, Wu X, Liu H. Impact of a single distance phase retrieval algorithm on spatial resolution in X-ray inline phase sensitive imaging. BIOMEDICAL SPECTROSCOPY AND IMAGING 2019; 8:29-40. [PMID: 31788419 PMCID: PMC6883648 DOI: 10.3233/bsi-190186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
A single-projection based phase retrieval method based on the phase attenuation duality principle (PAD) was used to compare the spatial resolution of the acquired phase sensitive and PAD processed phase retrieved images. An inline phase sensitive prototype was used to acquire the phase sensitive images. The prototype incorporates a micro-focus x-ray source and a flat panel detector with a 50 μm pixel pitch. A phantom composed of a 2 cm thick 50-50 adipose-glandular mimicking slab sandwiched with a 0.82 cm thick slanted PMMA sharp edge was used. Phase sensitive image of the phantom was acquired at 120 kV, 3.35 mAs with a 16 μm tube focal spot size under a geometric magnification (M) of 2.5. The PAD based method was applied to the acquired phase sensitive image for the retrieval of phase values. With necessary data processing, modulation transfer function (MTF) curves were determined for the estimation and comparison of the spatial resolution. The PAD processed phase retrieved values of the phantom were in good agreement with the theoretically calculated values. Phase sensitive images showed higher spatial resolution at all spatial frequencies compared to the phase retrieved images. It was noted that the high-frequency signal components in the retrieved image were suppressed that resulted in lower MTF values. When compared to the phase sensitive image, the cutoff resolution (10% MTF) for phase retrieved image dropped 32% from 15.6 lp/mm (32μm) to 10.6 lp/mm (47μm). The resolution offered by this phase sensitive prototype is radiographically enough to detect breast cancer.
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Affiliation(s)
- Muhammad. U. Ghani
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma,
Norman, OK 73019, USA
| | - Bradley Gregory
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma,
Norman, OK 73019, USA
| | - Farid Omoumi
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma,
Norman, OK 73019, USA
| | - Bin Zheng
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma,
Norman, OK 73019, USA
| | - Aimin Yan
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, 35249, USA
| | - Xizeng Wu
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, 35249, USA
| | - Hong Liu
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma,
Norman, OK 73019, USA
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Wang Z, Ren K, Shi X, Liu D, Wu Z, Gao K. Technical Note: Single-shot phase retrieval method for synchrotron-based high-energy x-ray grating interferometry. Med Phys 2019; 46:1317-1322. [DOI: 10.1002/mp.13399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 11/20/2018] [Accepted: 01/18/2019] [Indexed: 01/31/2023] Open
Affiliation(s)
- Zhili Wang
- School of Electronic Science & Applied Physics; Hefei University of Technology; Hefei 230009 China
- Beijing Advanced Innovation Center for Imaging Technology; Capital Normal University; Beijing 100048 People's Republic of China
| | - Kun Ren
- School of Electronic Science & Applied Physics; Hefei University of Technology; Hefei 230009 China
| | - Xiaomin Shi
- School of Electronic Science & Applied Physics; Hefei University of Technology; Hefei 230009 China
| | - Dalin Liu
- School of Electronic Science & Applied Physics; Hefei University of Technology; Hefei 230009 China
| | - Zhao Wu
- National Synchrotron Radiation Laboratory University of Science and Technology of China; 230029 Hefei China
| | - Kun Gao
- National Synchrotron Radiation Laboratory University of Science and Technology of China; 230029 Hefei China
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Ghani MU, Wong MD, Omoumi FH, Zheng B, Fajardo LL, Yan A, Wu X, Liu H. Detectability comparison of simulated tumors in digital breast tomosynthesis using high-energy X-ray inline phase sensitive and commercial imaging systems. Phys Med 2018; 47:34-41. [PMID: 29609816 DOI: 10.1016/j.ejmp.2018.02.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 01/22/2018] [Accepted: 02/15/2018] [Indexed: 11/28/2022] Open
Abstract
This study compared the detectability of simulated tumors using a high-energy X-ray inline phase sensitive digital breast tomosynthesis (DBT) prototype and a commercial attenuation-based DBT system. Each system imaged a 5-cm thick modular breast phantom with 50-50 adipose-glandular percentage density containing contrast-detail (CD) test objects to simulate different tumor sizes. A commercial DBT system acquired 15 projection views over 15 degrees (15d-15p) was used to acquire the attenuation-based projection views and to reconstruct the conventional DBT slices. Attenuation-based projection views were acquired at 32 kV, 46 mAs with a mean glandular dose (Dg) of 1.6 mGy. For acquiring phase sensitive projection views, the prototype utilized two acquisition geometries: 11 projection views were acquired over 15 degrees (15d-11p), and 17 projection views were acquired over 16 degrees (16d-17p) at 120 kV, 5.27 mAs with 1.51 mGy under the magnification (M) of 2. A phase retrieval algorithm based on the phase-attenuation duality (PAD) was applied to each projection view, and a modified Feldkamp-Davis-Kress (FDK) algorithm was used to reconstruct the phase sensitive DBT slices. Simulated tumor margins were rated as more conspicuous and better visualized for both phase sensitive acquisition geometries versus conventional DBT imaging. The CD curves confirmed the improvement in both contrast and spatial resolutions with the phase sensitive DBT imaging. The superiority of the phase sensitive DBT imaging was further endorsed by higher contrast to noise ratio (CNR) and figure-of-merit (FOM) values. The CNR improvements provided by the phase sensitive DBT prototype were sufficient to offset the noise reduction provided by the attenuation-based DBT imaging.
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Affiliation(s)
- Muhammad U Ghani
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK 73019, USA.
| | - Molly D Wong
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK 73019, USA.
| | - Farid H Omoumi
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK 73019, USA.
| | - Bin Zheng
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK 73019, USA.
| | - Laurie L Fajardo
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT 84132, USA.
| | - Aimin Yan
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL 35249, USA.
| | - Xizeng Wu
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL 35249, USA.
| | - Hong Liu
- Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK 73019, USA.
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Ren L, Zheng B, Liu H. Tutorial on X-ray photon counting detector characterization. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2018; 26:1-28. [PMID: 29154310 PMCID: PMC5909414 DOI: 10.3233/xst-16210] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
BACKGROUND Recent advances in photon counting detection technology have led to significant research interest in X-ray imaging. OBJECTIVE As a tutorial level review, this paper covers a wide range of aspects related to X-ray photon counting detector characterization. METHODS The tutorial begins with a detailed description of the working principle and operating modes of a pixelated X-ray photon counting detector with basic architecture and detection mechanism. Currently available methods and techniques for charactering major aspects including energy response, noise floor, energy resolution, count rate performance (detector efficiency), and charge sharing effect of photon counting detectors are comprehensively reviewed. Other characterization aspects such as point spread function (PSF), line spread function (LSF), contrast transfer function (CTF), modulation transfer function (MTF), noise power spectrum (NPS), detective quantum efficiency (DQE), bias voltage, radiation damage, and polarization effect are also remarked. RESULTS A cadmium telluride (CdTe) pixelated photon counting detector is employed for part of the characterization demonstration and the results are presented. CONCLUSIONS This review can serve as a tutorial for X-ray imaging researchers and investigators to understand, operate, characterize, and optimize photon counting detectors for a variety of applications.
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Affiliation(s)
- Liqiang Ren
- 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
| | - Hong Liu
- Center for Biomedical Engineering and School of Electrical and Computer
Engineering, University of Oklahoma, Norman, OK 73019, USA
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Wu D, Wong MD, Li Y, Fajardo L, Zheng B, Wu X, Liu H. Quantitative investigation of the edge enhancement in in-line phase contrast projections and tomosynthesis provided by distributing microbubbles on the interface between two tissues: a phantom study. Phys Med Biol 2017; 62:9357-9376. [PMID: 29161236 PMCID: PMC5731655 DOI: 10.1088/1361-6560/aa9548] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The objective of this study was to quantitatively investigate the ability to distribute microbubbles along the interface between two tissues, in an effort to improve the edge and/or boundary features in phase contrast imaging. The experiments were conducted by employing a custom designed tissue simulating phantom, which also simulated a clinical condition where the ligand-targeted microbubbles are self-aggregated on the endothelium of blood vessels surrounding malignant cells. Four different concentrations of microbubble suspensions were injected into the phantom: 0%, 0.1%, 0.2%, and 0.4%. A time delay of 5 min was implemented before image acquisition to allow the microbubbles to become distributed at the interface between the acrylic and the cavity simulating a blood vessel segment. For comparison purposes, images were acquired using three system configurations for both projection and tomosynthesis imaging with a fixed radiation dose delivery: conventional low-energy contact mode, low-energy in-line phase contrast and high-energy in-line phase contrast. The resultant images illustrate the edge feature enhancements in the in-line phase contrast imaging mode when the microbubble concentration is extremely low. The quantitative edge-enhancement-to-noise ratio calculations not only agree with the direct image observations, but also indicate that the edge feature enhancement can be improved by increasing the microbubble concentration. In addition, high-energy in-line phase contrast imaging provided better performance in detecting low-concentration microbubble distributions.
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Affiliation(s)
- Di Wu
- School of Electrical and Computer Engineering, University of Oklahoma, 110 West Boyd Street, Norman, OK 73019, United States of America
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Wu D, Wong MD, Yang K, Yan A, Li Y, Fajardo L, Zheng B, Wu X, Liu H. Using Microbubble as Contrast Agent for High-Energy X-Ray In-line Phase Contrast Imaging: Demonstration and Comparison Study. IEEE Trans Biomed Eng 2017; 65:1117-1123. [PMID: 28829304 DOI: 10.1109/tbme.2017.2741942] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The ability of microbubbles to benefit the imaging quality of high-energy in-line phase contrast as compared with conventional low-energy contact mode radiography was investigated. The study was conducted by comparing in-line phase contrast imaging with conventional contact-mode projection imaging under the same dose delivered to a phantom. A custom-designed phantom was employed to simulate a segment of human blood vessel injected with microbubble suspensions. The microbubbles were suspended in deionized water to obtain different volume concentrations. The area contrast-to-noise ratio (CNR) values corresponding to both imaging methods were measured for different microbubble volume concentrations. The phase contrast images were processed by phase-attenuation duality phase retrieval to preserve the imaging quality. Comparison of the resultant CNR values indicates that the microbubble suspension images deliver a higher CNR than the water-only image, with monotonically increasing trends between the CNR values and microbubble concentrations. Compared to low-energy conventional images of the microbubble suspensions, high-energy in-line phase contrast CNRs are lower at high concentrations and are comparable, even better than, at low concentrations. This result suggests that 1) the performance of copolymer-shell microbubble employed in this study as x-ray contrast agent is constrained by the detective quantum efficiency of the system and the attenuation properties of the shell materials, 2) the phase-attenuation duality phase retrieval method has the potential to preserve image quality for areas with low concentration of microbubbles, and 3) the selection of microbubble products as a phase contrast agent may follow criteria of minimizing the impact of absorption attenuation properties of the shells and maximizing the difference factor of electron densities.
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Lee C, Baek J. Inverse filtering approach to measure directional in-plane modulation transfer function using a sphere phantom for a digital tomosynthesis system. OPTICS EXPRESS 2017; 25:17280-17293. [PMID: 28789221 DOI: 10.1364/oe.25.017280] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 07/04/2017] [Indexed: 06/07/2023]
Abstract
We propose a method to measure the directional in-plane modulation transfer function (MTF) of a digital tomosynthesis system using a sphere phantom. To assess the spatial resolution of an in-plane image of the tomosynthesis system, projection data of a sphere phantom were generated within a limited data acquisition range of 40°, and reconstructed by the FDK algorithm. To measure the in-plane MTF, we divided the Fourier transform of the reconstructed sphere phantom by that of the ideal sphere phantom, and then performed plane integral along the fz-direction. When dividing, small values in the denominator can introduce estimation errors, and these errors were reduced by the proposed method. To evaluate the performance of the proposed method, the in-plane MTF estimated by simulation and experimental data was compared to the ideal in-plane MTF generated by computer simulations using a point object. For quantitative evaluation, we measured frequency values at half-maximum and full-maximum of the directional in-plane MTF along the three different directions (i.e., f0° -, f30° -, and f60° -directions) and compared them with those of the ideal in-plane MTF. Although the sphere phantom has been regarded as an inappropriate object due to the anisotropic characteristics of tomosynthesis image, our results show that the proposed method has a reliable estimation performance, demonstrating the sphere phantom is still suitable for measuring the directional in-plane MTF for a digital tomosynthesis system.
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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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Ghani MU, Wong MD, Wu D, Zheng B, Fajardo LL, Yan A, Fuh J, Wu X, Liu H. Detectability comparison between a high energy x-ray phase sensitive and mammography systems in imaging phantoms with varying glandular-adipose ratios. Phys Med Biol 2017; 62:3523-3538. [PMID: 28379851 DOI: 10.1088/1361-6560/aa644b] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The objective of this study was to demonstrate the potential benefits of using high energy x-rays in comparison with the conventional mammography imaging systems for phase sensitive imaging of breast tissues with varying glandular-adipose ratios. This study employed two modular phantoms simulating the glandular (G) and adipose (A) breast tissue composition in 50 G-50 A and 70 G-30 A percentage densities. Each phantom had a thickness of 5 cm with a contrast detail test pattern embedded in the middle. For both phantoms, the phase contrast images were acquired using a micro-focus x-ray source operated at 120 kVp and 4.5 mAs, with a magnification factor (M) of 2.5 and a detector with a 50 µm pixel pitch. The mean glandular dose delivered to the 50 G-50 A and 70 G-30 A phantom sets were 1.33 and 1.3 mGy, respectively. A phase retrieval algorithm based on the phase attenuation duality that required only a single phase contrast image was applied. Conventional low energy mammography images were acquired using GE Senographe DS and Hologic Selenia systems utilizing their automatic exposure control (AEC) settings. In addition, the automatic contrast mode (CNT) was also used for the acquisition with the GE system. The AEC mode applied higher dose settings for the 70 G-30 A phantom set. As compared to the phase contrast images, the dose levels for the AEC mode acquired images were similar while the dose levels for the CNT mode were almost double. The observer study, contrast-to-noise ratio and figure of merit comparisons indicated a large improvement with the phase retrieved images in comparison to the AEC mode images acquired with the clinical systems for both density levels. As the glandular composition increased, the detectability of smaller discs decreased with the clinical systems, particularly with the GE system, even at higher dose settings. As compared to the CNT mode (double dose) images, the observer study also indicated that the phase retrieved images provided similar or improved detection for all disc sizes except for the disk diameters of 2 mm and 1 mm for the 50 G-50 A phantom and 3 mm and 0.5 mm for the 70 G-30 A phantom. This study demonstrated the potential of utilizing a high energy phase sensitive x-ray imaging system to improve lesion detection and reduce radiation dose when imaging breast tissues with varying glandular compositions.
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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, United States of America
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Liu J, Cai W, Ning R. Evaluation of differential phase contrast cone beam CT imaging system. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2017; 25:357-372. [PMID: 27911351 DOI: 10.3233/xst-16184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Grating-based differential phase contrast (DPC) imaging enables the use of a hospital-grade X-ray tube, but compromises the image quality due to insufficiently coherent illumination. In this research, a bench-top DPC cone beam CT (DPC-CBCT) was systematically evaluated and compared with the traditional attenuation-based CBCT in terms of contrast to noise ratio, noise property, and contrast resolution through phantom studies. In order to evaluate DPC-CBCT for soft tissue imaging, breast specimen and small animal studies were carried out. Phantom studies indicate that phase image has lower-frequency noise, higher CNR, and improved contrast resolution. However, phase image quality was degraded in soft tissue imaging due to coherence loss caused by small-angle scattering. Hence dark-field imaging was introduced to quantitatively investigate small-angle scattering caused by an object. Experimental results indicate that inhomogeneous objects affect phase contrast imaging, phase image is more sensitive to noise, and its performance is material dependent. Dark-field imaging could also be used to locate and reduce phase image noise and artifact caused by small-angle scattering.
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Affiliation(s)
- Jiangkun Liu
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
| | - Weixing Cai
- Department of Physics and Astronomy, University of Rochester, Rochester, NY, USA
| | - Ruola Ning
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY, USA
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Lee C, Baek J. A Sphere Phantom Approach to Measure Directional Modulation Transfer Functions for Tomosynthesis Imaging Systems. IEEE TRANSACTIONS ON MEDICAL IMAGING 2016; 35:871-881. [PMID: 26571519 DOI: 10.1109/tmi.2015.2498930] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We propose a sphere phantom approach to measure spatially varying directional modulation transfer functions (MTFs) for tomosynthesis imaging systems. Since the reconstructed tomosynthesis images contain significant artifacts, traditional background detrending techniques may not be effective to estimate the background trends accurately, which is essential to acquire sphere only data. A background detrending technique optimized for local volumes with different cone angles is presented. To measure directional MTFs, we calculate plane integrals of ideal sphere phantom and sphere only data. To minimize the effects of the high level of noise in tomosynthesis images, Richardson-Lucy deconvolution with Tikhonov-Miller is used to estimate directional plane spread function (PlSF). Then, directional MTFs are calculated by taking the modulus of the Fourier transform of the directional PlSFs. The measured directional MTFs are compared with the ideal directional MTFs calculated from a simulated point object. Our results show that the proposed method reliably measures directional MTFs along any desired directions, especially near low frequency regions.
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