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Massera RT, Dehairs M, Verhoeven H, Bosmans H, Marshall N. A comprehensive assessment of a prototype high ratio antiscatter grid in interventional cardiology using experimental measurements and Monte Carlo simulations. Phys Med Biol 2024; 69:135015. [PMID: 38862002 DOI: 10.1088/1361-6560/ad56f3] [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: 11/20/2023] [Accepted: 06/11/2024] [Indexed: 06/13/2024]
Abstract
Objective. To assess the performance of a new antiscatter grid design in interventional cardiology for image quality improvement and dose reduction using experimental measurements and Monte Carlo (MC) simulation.Approach.Experimental measurements were performed on an angiography system, using a multi-layered tissue simulating composite phantom made from of poly(methyl methacrylate), aluminium and expanded polystyrene (2/0.2/0.7 cm). The total phantom thickness ranged from 20.3 cm to 40.6 cm. Four conditions were compared; (A) 105 cm source-image receptor distance (SID) without grid, (Bi) 105 cm SID with grid ratio (r) and strip density (N) (r15N80), (Bii) 120 cm SID without grid, and (Biii) 120 cm SID with high ratio grid (r29N80). The system efficiency (η), defined by the signal-to-noise ratio, was compared from theBconditions against caseA. These conditions were also simulated with MC techniques, allowing additional phantom compositions to be explored. Weighted image quality improvement factor (ηw(u)) was studied experimentally at a specific spatial frequency due to the SID change. Images were simulated with an anthropomorphic chest phantom for the different conditions, and the system efficiency was compared for the different anatomical regions.Main results.Good agreement was found between theηandηw(u) methods using both measured and simulated data, with average relative differences between 2%-11%. CaseBiiiprovided higherηvalues compared toA, andBifor thicknesses larger than 20.3 cm. In addition, caseBiiialso provided higherηvalues for high attenuating areas in the anthropomorphic phantom, such as behind the spine.Significance.The new antiscatter grid design provided higher system efficiency compared to the standard grid for the parameters explored in this work.
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Affiliation(s)
- Rodrigo T Massera
- Medical Imaging Research Centre, Medical Physics and Quality Assessment, KU Leuven, 3000 Leuven, Belgium
| | - Michiel Dehairs
- Medical Imaging Research Centre, Medical Physics and Quality Assessment, KU Leuven, 3000 Leuven, Belgium
- Department of Medical Physics, Institute Jules Bordet Instituut, Rue Meylemeersch 90, Bruxelles 1070, Belgium
| | - Hannelore Verhoeven
- Competentiecentrum medische stralingsfysica, UZ Gasthuisberg, Herestraat 49, 3000 Leuven, Belgium
| | - Hilde Bosmans
- Medical Imaging Research Centre, Medical Physics and Quality Assessment, KU Leuven, 3000 Leuven, Belgium
- Competentiecentrum medische stralingsfysica, UZ Gasthuisberg, Herestraat 49, 3000 Leuven, Belgium
| | - Nicholas Marshall
- Medical Imaging Research Centre, Medical Physics and Quality Assessment, KU Leuven, 3000 Leuven, Belgium
- Competentiecentrum medische stralingsfysica, UZ Gasthuisberg, Herestraat 49, 3000 Leuven, Belgium
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Marshall NW, Vandenbroucke D, Cockmartin L, Wanninger F, Smet M, Feng Y, Ni Y, Bosmans H. Seven general radiography x-ray detectors with pixel sizes ranging from 175 to 76 μm: technical evaluation with the focus on orthopaedic imaging. Phys Med Biol 2023; 68:195007. [PMID: 37659394 DOI: 10.1088/1361-6560/acf642] [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: 04/27/2023] [Accepted: 09/01/2023] [Indexed: 09/04/2023]
Abstract
Aim. Flat panel detectors with small pixel sizes general can potentially improve imaging performance in radiography applications requiring fine detail resolution. This study evaluated the imaging performance of seven detectors, covering a wide range of pixel sizes, in the frame of orthopaedic applications.Material and methods. Pixel sizes ranged from 175 (detector A175) to 76μm (detector G76). Modulation transfer function (MTF) and detective quantum efficiency (DQE) were measured using International Electrotechnical Commission (IEC) RQA3 beam quality. Threshold contrast (CT) and a detectability index (d') were measured at three air kerma/image levels. Rabbit shoulder images acquired at 60 kV, over five air kerma levels, were evaluated in a visual grading study for anatomical sharpness, image noise and overall diagnostic image quality by four radiologists. The detectors were compared to detector E124.Results. The 10% point of the MTF ranged from 3.21 to 4.80 mm-1, in going from detector A175to detector G76. DQE(0.5 mm-1) measured at 2.38μGy/image was 0.50 ± 0.05 for six detectors, but was higher for F100at 0.62. High frequency DQE was superior for the smaller pixel detectors, howeverCTfor 0.25 mm discs correlated best with DQE(0.5 mm-1). Correlation betweenCTand the detectability model was good (R2= 0.964).CTfor 0.25 mm diameter discs was significantly higher for D150and F100compared to E124. The visual grading data revealed higher image quality ratings for detectors D125and F100compared to E124. An increase in air kerma was associated with improved perceived sharpness and overall quality score, independent of detector. Detectors B150, D125, F100and G76, performed well in specific tests, however only F100consistently outperformed the reference detector.Conclusion. Pixel size alone was not a reliable predictor of small detail detectability or even perceived sharpness in a visual grading analysis study.
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Affiliation(s)
- N W Marshall
- UZ Gasthuisberg, Department of Radiology, Herestraat 49, B-3000 Leuven, Belgium
- Medical Imaging Research Center, Medical Physics and Quality Assessment, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
- Agfa N.V., Septestraat 27, B-2640 Mortsel, Belgium
| | | | - L Cockmartin
- UZ Gasthuisberg, Department of Radiology, Herestraat 49, B-3000 Leuven, Belgium
| | - F Wanninger
- Agfa-Gevaert HealthCare GmbH, München, Germany
| | - M Smet
- UZ Gasthuisberg, Department of Radiology, Herestraat 49, B-3000 Leuven, Belgium
| | - Y Feng
- Theragnostic Laboratory, Biomedical Group, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
| | - Y Ni
- Theragnostic Laboratory, Biomedical Group, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
| | - H Bosmans
- UZ Gasthuisberg, Department of Radiology, Herestraat 49, B-3000 Leuven, Belgium
- Medical Imaging Research Center, Medical Physics and Quality Assessment, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
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Chavarria MA, Huser M, Blanc S, Monnin P, Schmid J, Chênes C, Assassi L, Blanchard H, Sahli R, Thiran JP, Salathé R, Schönenberger K. X-ray imaging detector for radiological applications adapted to the context and requirements of low- and middle-income countries. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:034102. [PMID: 35364973 DOI: 10.1063/5.0077985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 02/20/2022] [Indexed: 06/14/2023]
Abstract
This paper describes the development of a novel medical x-ray imaging system adapted to the needs and constraints of low- and middle-income countries. The developed system is based on an indirect conversion chain: a scintillator plate produces visible light when excited by the x rays, and then, a calibrated multi-camera architecture converts the visible light from the scintillator into a set of digital images. The partial images are then unwarped, enhanced, and stitched through parallel field programmable gate array processing units and specialized software. All the detector components were carefully selected focusing on optimizing the system's image quality, robustness, cost-effectiveness, and capability to work in harsh tropical environments. With this aim, different customized and commercial components were characterized. The resulting detector can generate high quality medical diagnostic images with detective quantum efficiency levels up to 60% (@2.34 μGy), even under harsh environments, i.e., 60 °C and 98% humidity.
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Affiliation(s)
- Mario Andrés Chavarria
- EssentialTech Centre, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Matthias Huser
- Ecole Technique-Ecole des Métiers-Lausanne (ETML), Lausanne CH-1004, Switzerland
| | - Sebastien Blanc
- EssentialTech Centre, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Pascal Monnin
- Institute of Radiation Physics (IRA), Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne CH-1007, Switzerland
| | - Jérôme Schmid
- Geneva School of Health Sciences, HES-SO University of Applied Sciences and Arts Western Switzerland, Genève CH-1206, Switzerland
| | - Christophe Chênes
- Geneva School of Health Sciences, HES-SO University of Applied Sciences and Arts Western Switzerland, Genève CH-1206, Switzerland
| | - Lazhari Assassi
- Geneva School of Health Sciences, HES-SO University of Applied Sciences and Arts Western Switzerland, Genève CH-1206, Switzerland
| | | | | | - Jean Philippe Thiran
- Signal Processing Laboratory 5, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - René Salathé
- School of Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Klaus Schönenberger
- EssentialTech Centre, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
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Zhou Y, Zhou Q, Niu X, Yan ZG, Lin T, Xiao J, Han X. Compositional Engineering of Doped Zero-dimensional Zinc Halide Blue Emitters for Efficient X-ray Scintillation. Inorg Chem Front 2022. [DOI: 10.1039/d2qi00461e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recently, the doped ternary zinc halides with high photoluminescence quantum yields (PLQYs) have demonstrated great potential in light emitting applications. However, the composition-dependent photophysical properties of ternary zinc halides have...
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Ou X, Chen X, Xu X, Xie L, Chen X, Hong Z, Bai H, Liu X, Chen Q, Li L, Yang H. Recent Development in X-Ray Imaging Technology: Future and Challenges. RESEARCH (WASHINGTON, D.C.) 2021; 2021:9892152. [PMID: 35028585 PMCID: PMC8724686 DOI: 10.34133/2021/9892152] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Accepted: 11/23/2021] [Indexed: 11/18/2022]
Abstract
X-ray imaging is a low-cost, powerful technology that has been extensively used in medical diagnosis and industrial nondestructive inspection. The ability of X-rays to penetrate through the body presents great advances for noninvasive imaging of its internal structure. In particular, the technological importance of X-ray imaging has led to the rapid development of high-performance X-ray detectors and the associated imaging applications. Here, we present an overview of the recent development of X-ray imaging-related technologies since the discovery of X-rays in the 1890s and discuss the fundamental mechanism of diverse X-ray imaging instruments, as well as their advantages and disadvantages on X-ray imaging performance. We also highlight various applications of advanced X-ray imaging in a diversity of fields. We further discuss future research directions and challenges in developing advanced next-generation materials that are crucial to the fabrication of flexible, low-dose, high-resolution X-ray imaging detectors.
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Affiliation(s)
- Xiangyu Ou
- MOE Key Laboratory for Analytical Science of Food Safety and Biology, College of Chemistry, Fuzhou University, Fuzhou 350108, China
| | - Xue Chen
- Frontiers Science Center for Flexible Electronics, Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an 710072, China
| | - Xianning Xu
- Frontiers Science Center for Flexible Electronics, Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an 710072, China
| | - Lili Xie
- MOE Key Laboratory for Analytical Science of Food Safety and Biology, College of Chemistry, Fuzhou University, Fuzhou 350108, China
| | - Xiaofeng Chen
- MOE Key Laboratory for Analytical Science of Food Safety and Biology, College of Chemistry, Fuzhou University, Fuzhou 350108, China
| | - Zhongzhu Hong
- MOE Key Laboratory for Analytical Science of Food Safety and Biology, College of Chemistry, Fuzhou University, Fuzhou 350108, China
| | - Hua Bai
- Frontiers Science Center for Flexible Electronics, Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an 710072, China
| | - Xiaowang Liu
- Frontiers Science Center for Flexible Electronics, Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an 710072, China
| | - Qiushui Chen
- MOE Key Laboratory for Analytical Science of Food Safety and Biology, College of Chemistry, Fuzhou University, Fuzhou 350108, China
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China
| | - Lin Li
- Frontiers Science Center for Flexible Electronics, Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an 710072, China
| | - Huanghao Yang
- MOE Key Laboratory for Analytical Science of Food Safety and Biology, College of Chemistry, Fuzhou University, Fuzhou 350108, China
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China
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Zhou Q, Ren J, Xiao J, Lei L, Liao F, Di H, Wang C, Yang L, Chen Q, Yang X, Zhao Y, Han X. Highly efficient copper halide scintillators for high-performance and dynamic X-ray imaging. NANOSCALE 2021; 13:19894-19902. [PMID: 34761770 DOI: 10.1039/d1nr03996b] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Progress towards high performance X-ray detection and dynamic imaging applications, including nondestructive inspection, homeland security, and medical diagnostics, requires scintillators with a high light yield, a reasonable decay time, low cost, and eco-friendliness. Recently, copper halide scintillators have drawn tremendous attention due to their outstanding radioluminescence performance. Here, we first employed β-Cs3Cu2Cl5 as a high-performance scintillator, with a photoluminescence quantum yield (PLQY) of 94.6%, a radioluminescence light yield of 34 000 ± 4000 photons per MeV, a low detection limit of 81.7 nGyair s-1, and good operational stability under a total X-ray dose of 174.6 Gyair in air. In addition, this scintillator presents a high spatial resolution of 9.6 lp mm-1 at the modulation transfer function of 0.2 and a superb performance at 60 frames per second in our X-ray imaging system. Overall, this highly efficient scintillator demonstrates outstanding comprehensive performance and shows great potential for broad applications in X-ray detection and dynamic imaging.
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Affiliation(s)
- Quan Zhou
- Institute of Materials, China Academy of Engineering Physics, Jiangyou 621908, China.
- Institute of Microstructure and Property of Advanced Materials, Beijing Key Lab of Microstructure and Property of Advanced Materials, Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China.
| | - Jiwei Ren
- Institute of Materials, China Academy of Engineering Physics, Jiangyou 621908, China.
| | - Jiawen Xiao
- Institute of Microstructure and Property of Advanced Materials, Beijing Key Lab of Microstructure and Property of Advanced Materials, Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China.
| | - Lin Lei
- Institute of Materials, China Academy of Engineering Physics, Jiangyou 621908, China.
| | - Feiyi Liao
- Institute of Materials, China Academy of Engineering Physics, Jiangyou 621908, China.
| | - Haipeng Di
- Institute of Materials, China Academy of Engineering Physics, Jiangyou 621908, China.
| | - Chao Wang
- Institute of Microstructure and Property of Advanced Materials, Beijing Key Lab of Microstructure and Property of Advanced Materials, Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China.
| | - Lijun Yang
- Institute of Materials, China Academy of Engineering Physics, Jiangyou 621908, China.
| | - Qi Chen
- School of Materials Science & Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Xiaofang Yang
- College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China
| | - Yiying Zhao
- Institute of Materials, China Academy of Engineering Physics, Jiangyou 621908, China.
| | - Xiaodong Han
- Institute of Microstructure and Property of Advanced Materials, Beijing Key Lab of Microstructure and Property of Advanced Materials, Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China.
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Ji X, Feng M, Treb K, Zhang R, Schafer S, Li K. Development of an Integrated C-Arm Interventional Imaging System With a Strip Photon Counting Detector and a Flat Panel Detector. IEEE TRANSACTIONS ON MEDICAL IMAGING 2021; 40:3674-3685. [PMID: 34232872 DOI: 10.1109/tmi.2021.3095419] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Modern interventional x-ray systems are often equipped with flat-panel detector-based cone-beam CT (FPD-CBCT) to provide tomographic, volumetric, and high spatial resolution imaging of interventional devices, iodinated vessels, and other objects. The purpose of this work was to bring an interchangeable strip photon-counting detector (PCD) to C-arm systems to supplement (instead of retiring) the existing FPD-CBCT with a high quality, spectral, and affordable PCD-CT imaging option. With minimal modification to the existing C-arm, a 51×0.6 cm2 PCD with a 0.75 mm CdTe layer, two energy thresholds, and 0.1 mm pixels was integrated with a Siemens Artis Zee interventional imaging system. The PCD can be translated in and out of the field-of-view to allow the system to switch between FPD and PCD-CT imaging modes. A dedicated phantom and a new algorithm were developed to calibrate the projection geometry of the narrow-beam PCD-CT system and correct the gantry wobbling-induced geometric distortion artifacts. In addition, a detector response calibration procedure was performed for each PCD pixel using materials with known radiological pathlengths to address concentric artifacts in PCD-CT images. Both phantom and human cadaver experiments were performed at a high gantry rotation speed and clinically relevant radiation dose level to evaluate the spectral and non-spectral imaging performance of the prototype system. Results show that the PCD-CT system has excellent image quality with negligible artifacts after the proposed corrections. Compared with FPD-CBCT images acquired at the same dose level, PCD-CT images demonstrated a 53% reduction in noise variance and additional quantitative imaging capability.
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Gao Y, Ge Y, Wang X, Liu J, Liu W, Cao Y, Gu K, Guo Z, Wei YM, Zhou N, Yu D, Meng H, Yu XF, Zheng H, Huang W, Li J. Ultrathin and Ultrasensitive Direct X-ray Detector Based on Heterojunction Phototransistors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101717. [PMID: 34219296 DOI: 10.1002/adma.202101717] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/21/2021] [Indexed: 06/13/2023]
Abstract
Most contemporary X-ray detectors adopt device structures with non/low-gain energy conversion, such that a fairly thick X-ray photoconductor or scintillator is required to generate sufficient X-ray-induced charges, and thus numerous merits for thin devices, such as mechanical flexibility and high spatial resolution, have to be compromised. This dilemma is overcome by adopting a new high-gain device concept of a heterojunction X-ray phototransistor. In contrast to conventional detectors, X-ray phototransistors allow both electrical gating and photodoping for effective carrier-density modulation, leading to high photoconductive gain and low noise. As a result, ultrahigh sensitivities of over 105 μC Gyair -1 cm-2 with low detection limit are achieved by just using an ≈50 nm thin photoconductor. The employment of ultrathin photoconductors also endows the detectors with superior flexibility and high imaging resolution. This concept offers great promise in realizing well-balanced detection performance, mechanical flexibility, integration, and cost for next-generation X-ray detectors.
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Affiliation(s)
- Yuanhong Gao
- Materials Interfaces Center, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Yongshuai Ge
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
- Center for Medical Artificial Intelligence, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Xinwei Wang
- School of Advanced Materials, Shenzhen Graduate School, Peking University, Shenzhen, 518055, P. R. China
| | - Jin Liu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Tat-sen University, Guangzhou, 510275, P. R. China
| | - Wenquan Liu
- Center for Opto-Electronic Engineering and Technology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Yong Cao
- Materials Interfaces Center, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Kaichen Gu
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Zheng Guo
- School of Advanced Materials, Shenzhen Graduate School, Peking University, Shenzhen, 518055, P. R. China
| | - Yu-Ming Wei
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Tat-sen University, Guangzhou, 510275, P. R. China
| | - Ni Zhou
- Materials Interfaces Center, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - De Yu
- Materials Interfaces Center, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Hong Meng
- School of Advanced Materials, Shenzhen Graduate School, Peking University, Shenzhen, 518055, P. R. China
| | - Xue-Feng Yu
- Materials Interfaces Center, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Hairong Zheng
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
- Center for Medical Artificial Intelligence, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Wei Huang
- Frontiers Science Center for Flexible Electronics, Xi'an Institute of Flexible Electronics (IFE) and Xi'an Institute of Biomedical Materials & Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, 710072, P. R. China
- State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing, 210023, P. R. China
- Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), South Puzhu Road, Nanjing, 211816, P. R. China
| | - Jia Li
- Materials Interfaces Center, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
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Datta A, Zhong Z, Motakef S. A new generation of direct X-ray detectors for medical and synchrotron imaging applications. Sci Rep 2020; 10:20097. [PMID: 33208782 PMCID: PMC7676260 DOI: 10.1038/s41598-020-76647-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 10/30/2020] [Indexed: 11/24/2022] Open
Abstract
Large-area X-ray imaging is one of the most widely used imaging modalities that spans several scientific and technological fields. Currently, the direct X-ray conversion materials that are being commercially used for large-area (> 8 cm × 4 cm without tiling) flat panel applications, such as amorphous selenium (a-Se), have usable sensitivities of up to only 30 keV. Although there have been many promising candidates (such as polycrystalline HgI2 and CdTe), none of the semiconductors were able to assuage the requirement for high energy (> 40 keV) large-area X-ray imaging applications due to inadequate cost, manufacturability, and long-term performance metrics. In this study, we successfully demonstrate the potential of the hybrid Methylammonium lead iodide (MAPbI3) perovskite-based semiconductor detectors in satisfying all the requirements for its successful commercialization in synchrotron and medical imaging. This new generation of hybrid detectors demonstrates low dark current under electric fields needed for high sensitivity X-ray imaging applications. The detectors have a linear response to X-ray energy and applied bias, no polarization effects at a moderate bias, and signal stability over long usage durations. Also, these detectors have demonstrated a stable detection response under BNL's National Synchrotron Light Source II (NSLS-II) 70 keV monochromatic synchrotron beamline.
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Affiliation(s)
- A Datta
- CapeSym, Inc., Natick, MA, 01760, USA.
| | - Z Zhong
- National Synchrotron Light Source I & II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - S Motakef
- CapeSym, Inc., Natick, MA, 01760, USA
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Javor D, Moyses J, Loewe C, Schernthaner RE. Radiation dose reduction capabilities of a new C-arm system with optimized hard- and software. Eur J Radiol 2020; 134:109367. [PMID: 33221618 DOI: 10.1016/j.ejrad.2020.109367] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 10/17/2020] [Accepted: 10/20/2020] [Indexed: 11/30/2022]
Abstract
PURPOSE To assess the radiation dose reduction capabilities and the image quality of a new C-arm system in comparison to a standard C-arm system. METHOD Prospective, randomized, IRB approved two-arm trial design. 49 consecutive patients with primary or secondary liver cancer were treated with transarterial chemoembolization (TACE) on two different angiography units. 28 patients were treated on a conventional angiography unit B, 21 patients on unit A which provides improved hardware and optimized image processing algorithms. Dose area product (DAP) and fluoroscopy time were recorded. DSA image quality of all procedures was assessed on a four-rank-scale by two independent and blinded readers. RESULTS Both cohorts showed no significant differences with regard to patient characteristics, tumor burden and fluoroscopy time. The new system resulted in a statistically significant reduction of cumulative DAP of 72% compared to the old platform (median 76 vs. 269 Gy*cm2). Individually, Fluoro-DAP and DSA-DAP decreased by 48% and 77% (p = 0.012 and p < 0.01), respectively. No statistically significant differences in DSA image quality were found between the two imaging platforms. CONCLUSIONS The new C-arm system significantly reduced radiation exposure for TACE procedures without increased radiation time or negative impact on DSA image quality. The combination of optimized hardware and software yields the highest radiation dose reduction and is of utmost importance for patients and interventionalists.
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Affiliation(s)
- Domagoj Javor
- Division of Cardiovascular and Interventional Radiology, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria.
| | - Johanna Moyses
- Division of Cardiovascular and Interventional Radiology, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria
| | - Christian Loewe
- Division of Cardiovascular and Interventional Radiology, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria
| | - Ruediger E Schernthaner
- Division of Cardiovascular and Interventional Radiology, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria
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Quantitative Analysis Methods Using Histogram and Entropy for Detector Performance Evaluation According to the Sensitivity Change of the Automatic Exposure Control in Digital Radiography. J Med Syst 2020; 44:183. [PMID: 32886270 DOI: 10.1007/s10916-020-01652-0] [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: 05/27/2020] [Accepted: 08/25/2020] [Indexed: 10/23/2022]
Abstract
The purpose of this study is to evaluate detector performance using histogram and entropy analysis according to the sensitivity change of the automatic exposure control (AEC). The experiment was performed as follows: The sensitivity of the detector was analyzed through a normalized histogram with sensitivities of S200, S400, S800, and S1000 of the AEC; the entropy of the image was then analyzed, and the signal volume of the detector was evaluated according to the sensitivity change. As the sensitivity of the AEC was increased from S200 to S1000, the histogram showed underflow, quantization separation, and dynamic range discrepancy. In addition, entropy showed a decrease as sensitivity was set higher; in particular, entropy degradation was more prominent at sensitivities above S800. Through the histogram and entropy analysis, it was concluded that the detector does not reproduce the sensitivity and signal volume accurately when the sensitivity of the AEC is set high in performance evaluation.
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Psichis K, Kalyvas N, Kandarakis I, Panayiotakis G. MTF of columnar phosphors with a homogenous part: an analytical approach. Med Biol Eng Comput 2020; 58:2551-2565. [PMID: 32815028 DOI: 10.1007/s11517-020-02243-4] [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: 07/30/2019] [Accepted: 07/30/2020] [Indexed: 11/26/2022]
Abstract
A method for the theoretical estimation of the MTF of columnar phosphors with a homogeneous part at the end used in X-ray imaging has been developed. This method considers the light transport inside the scintillator through an analytical modelling, the optical photon beams distribution on the scintillator-optical sensor interface, and uses the definition of the PSF and a Gauss fitted LSF to estimate the MTF of an indirect detector. This method was applied to a columnar CsI:Tl scintillator and validated against experimental results found in literature, and a good agreement was observed. It was found that, by increasing the pixel size of the optical detector and the thickness of the scintillator, the MTF decreased as expected. This method may be used in evaluating the performance of the columnar phosphors used in medical imaging, given their physical and geometrical characteristics.Graphical abstract (a) Side view of a part of the scintillator where five crystal columns with homogeneous ends attached to an optical sensor is shown. (b) Propagation of two random optical photon beams emitted from point K with different angles of emission is shown. All the symbols are explained analytically in the text.
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Affiliation(s)
- Konstantinos Psichis
- Department of Medical Physics, School of Medicine, University of Patras, 26500, Patras, Greece
| | - Nektarios Kalyvas
- Department of Biomedical Engineering, University of West Attica, 12210, Athens, Greece
| | - Ioannis Kandarakis
- Department of Biomedical Engineering, University of West Attica, 12210, Athens, Greece
| | - George Panayiotakis
- Department of Medical Physics, School of Medicine, University of Patras, 26500, Patras, Greece.
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Beck S, Sellerer T, Mechlem K, Bodden J, Meurer F, Sauter A, Herzen J, Pfeiffer F, Pfeiffer D. Photon-counting spectral basis component material decomposition for musculoskeletal radiographs. Sci Rep 2020; 10:13889. [PMID: 32807855 PMCID: PMC7431848 DOI: 10.1038/s41598-020-70363-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 07/08/2020] [Indexed: 11/09/2022] Open
Abstract
As a very fast and non-invasive examination, conventional X-ray radiography is well established as the first line diagnostic imaging method of the human bone system. While major bone injuries such as fractures and dislocations are usually easily detectable on conventional X-ray images, more subtle injuries such as microfractures are often missed, leading to mistreatment and potential long-term consequences. The technology of Photon-Counting Dual-Energy Radiography (PCDER) yields the possibility to decompose conventional X-ray images into basis material images such as bone- and soft-tissue-equivalence images. The obtained basis material images offer significant advantages in terms of image contrast and image details over the raw attenuation image which shows an overlap of bone and soft tissue. Whereas the advantages of bone- and soft-tissue-equivalence images have been broadly discussed referring to bone subtraction images in the detection of pulmonary diseases, this method has not been considered for the analysis of musculoskeletal images until present. In this study we show that basis component equivalence images have high potential to improve the diagnostic accuracy of the detection of minor bone lesions during clinical trauma imaging. A reader study performed by three experienced radiologists compares the image quality of basis material images to a standard radiograph image of a non-fractured cadaveric hand.
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Affiliation(s)
- Stefanie Beck
- Department of Diagnostic and Interventional Radiology, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany.
| | - Thorsten Sellerer
- Chair of Biomedical Physics, Department of Physics and Munich School of Bioengineering, Technical University of Munich, 85748, Garching, Germany
| | - Korbinian Mechlem
- Chair of Biomedical Physics, Department of Physics and Munich School of Bioengineering, Technical University of Munich, 85748, Garching, Germany
| | - Jannis Bodden
- Department of Diagnostic and Interventional Radiology, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Felix Meurer
- Department of Diagnostic and Interventional Radiology, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Andreas Sauter
- Department of Diagnostic and Interventional Radiology, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
| | - Julia Herzen
- Chair of Biomedical Physics, Department of Physics and Munich School of Bioengineering, Technical University of Munich, 85748, Garching, Germany
| | - Franz Pfeiffer
- Chair of Biomedical Physics, Department of Physics and Munich School of Bioengineering, Technical University of Munich, 85748, Garching, Germany
| | - Daniela Pfeiffer
- Department of Diagnostic and Interventional Radiology, Klinikum Rechts Der Isar, Technical University of Munich, 81675, Munich, Germany
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14
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Zhao X, Niu G, Zhu J, Yang B, Yuan JH, Li S, Gao W, Hu Q, Yin L, Xue KH, Lifshitz E, Miao X, Tang J. All-Inorganic Copper Halide as a Stable and Self-Absorption-Free X-ray Scintillator. J Phys Chem Lett 2020; 11:1873-1880. [PMID: 32040318 DOI: 10.1021/acs.jpclett.0c00161] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Lead halide perovskites have recently shown great potential as X-ray scintillators; however, the toxicity of the lead element seriously restricts their applications. Herein we report a new lead-free and self-absorption-free scintillator based on Rb2CuCl3 metal halide. The Rb2CuCl3 exhibits a near-unity photoluminescence quantum yield (99.4%) as well as a long photoluminescence lifetime (11.3 μs). Furthermore, Rb2CuCl3 demonstrates an appreciable light yield of 16 600 photons per megaelectronvolt and a large scintillation response with a linear range from 48.6 nGyair s-1 to 15.7 μGyair s-1. Notably, the detection limit is as low as 88.5 nGyair s-1, enabling a reduced radiation dose to the human body when a medical and security check is conducted. In addition, Rb2CuCl3 exhibits good stability against the atmosphere, continuous ultraviolet light, as well as X-ray irradiation. The combination of the decent scintillation performance, low toxicity and good stability suggests the Rb2CuCl3 could be a possible promising X-ray scintillator.
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Affiliation(s)
- Xue Zhao
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
| | - Guangda Niu
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
| | - Jinsong Zhu
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
| | - Bo Yang
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
| | - Jun-Hui Yuan
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
| | - Shunran Li
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
| | - Wanru Gao
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
| | - Qingsong Hu
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
| | - Lixiao Yin
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
| | - Kan-Hao Xue
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
| | - Efrat Lifshitz
- Schulich Faculty of Chemistry, Russell Berrie Nanotechnology Institute and Solid State Institute, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Xiangshui Miao
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
| | - Jiang Tang
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
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Pros, cons and future perspectives - three questions on three dimensional guidance for cardiac catheterization in congenital heart disease. ADVANCES IN INTERVENTIONAL CARDIOLOGY 2019; 15:263-273. [PMID: 31592250 PMCID: PMC6777176 DOI: 10.5114/aic.2019.87688] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 08/11/2019] [Indexed: 02/01/2023] Open
Abstract
Step changes in angiographic imaging are not commonplace. Since the move from analogue to digital and flat detector plates, two-dimensional imaging technology has certainly evolved but not jumped forward. Of all the routine imaging techniques used in cardiology, angiography has been the last modality to embrace the third dimension. Although the development of rotational angiography was initially for the benefit of neuroimaging and fusion of cross sectional datasets was aimed at the treatment of descending aortic pathology, interventional physicians in congenital and structural cardiology have immersed themselves in this technology over the last 10 years. Like many disruptive technologies, its introduction has divided opinion. We aimed to explore the mindset of those in the field of interventional cardiology who are driving imaging forward. These structured interviews recorded during the 21st Pediatric and Adult Interventional Cardiac Symposium illustrate the challenges and sticking points as well as giving an insight into the direction of travel for three-dimensional imaging and fusion techniques. Covering a wide range of career development, seniority and experience, the interviewees in this article are probably responsible for the majority of the published literature on invasive three-dimensional imaging in congenital heart disease.
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Fetterly KA. Performance assessment of active vs passive pixel x‐ray angiography detector systems using a bias‐corrected channelized Hotelling observer and adult patient‐equivalent experimental conditions. Med Phys 2018; 45:4888-4896. [DOI: 10.1002/mp.13192] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 08/22/2018] [Accepted: 08/23/2018] [Indexed: 01/02/2023] Open
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Heo JH, Shin DH, Park JK, Kim DH, Lee SJ, Im SH. High-Performance Next-Generation Perovskite Nanocrystal Scintillator for Nondestructive X-Ray Imaging. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1801743. [PMID: 30141200 DOI: 10.1002/adma.201801743] [Citation(s) in RCA: 129] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 05/28/2018] [Indexed: 05/12/2023]
Abstract
Readily commercializable and cost-effective next-generation CsPbBr3 perovskite nanocrystals (PNCs) based X-ray detectors are demonstrated. The PNCs-based X-ray detector exhibits higher spatial resolution (9.8 lp mm-1 at modulation transfer function (MTF) = 0.2 and 12.5-8.9 lp mm-1 for a linear line chart), faster response time (≈200 ns), and comparable stability (>40 Gyair s-1 of X-ray exposure) compared with the commercialized terbium-doped gadolinium oxysulfide (GOS)-based detectors (spatial resolution = 6.2 lp mm-1 at MTF = 0.2 and 6.3 lp mm-1 for a linear line chart, response time = ≈1200 ns) because the PNCs-based scintillator has ≈5.6-fold faster average photoluminescence lifetime and stronger emission than the GOS-based one.
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Affiliation(s)
- Jin Hyuck Heo
- Department of Chemical and Biological engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 17104, Republic of Korea
| | - Dong Hee Shin
- Department of Chemical and Biological engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 17104, Republic of Korea
| | - Jin Kyoung Park
- Department of Chemical and Biological engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 17104, Republic of Korea
| | - Do Hun Kim
- Department of Chemical and Biological engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 17104, Republic of Korea
| | - Sang Jin Lee
- Department of Chemical and Biological engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 17104, Republic of Korea
| | - Sang Hyuk Im
- Department of Chemical and Biological engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 17104, Republic of Korea
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18
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Oliveira J, Correia V, Sowade E, Etxebarria I, Rodriguez RD, Mitra KY, Baumann RR, Lanceros-Mendez S. Indirect X-ray Detectors Based on Inkjet-Printed Photodetectors with a Screen-Printed Scintillator Layer. ACS APPLIED MATERIALS & INTERFACES 2018; 10:12904-12912. [PMID: 29580050 DOI: 10.1021/acsami.8b00828] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Organic photodetectors (PDs) based on printing technologies will allow to expand the current field of PD applications toward large-area and flexible applications in areas such as medical imaging, security, and quality control, among others. Inkjet printing is a powerful digital tool for the deposition of smart and functional materials on various substrates, allowing the development of electronic devices such as PDs on various substrates. In this work, inkjet-printed PD arrays, based on the organic thin-film transistor architecture, have been developed and applied for the indirect detection of X-ray radiation using a scintillator ink as an X-ray absorber. The >90% increase of the photocurrent of the PDs under X-ray radiation, from about 53 nA without the scintillator film to about 102 nA with the scintillator located on top of the PD, proves the suitability of the developed printed device for X-ray detection applications.
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Affiliation(s)
- Juliana Oliveira
- Centro de Física , Universidade do Minho , 4710-057 Braga , Portugal
- Algoritmi Research Center , Universidade do Minho , Campus de Azurém , 4800-058 Guimarães , Portugal
| | - Vitor Correia
- Centro de Física , Universidade do Minho , 4710-057 Braga , Portugal
- Algoritmi Research Center , Universidade do Minho , Campus de Azurém , 4800-058 Guimarães , Portugal
| | | | - Ikerne Etxebarria
- BCMaterials, Basque Center for Materials, Applications and Nanostructures , UPV/EHU Science Park , 48940 Leioa , Spain
| | | | | | - Reinhard R Baumann
- Department Printed Functionalities , Fraunhofer Institute for Electronic Nano Systems (ENAS) , 09126 Chemnitz , Germany
| | - Senentxu Lanceros-Mendez
- Centro de Física , Universidade do Minho , 4710-057 Braga , Portugal
- BCMaterials, Basque Center for Materials, Applications and Nanostructures , UPV/EHU Science Park , 48940 Leioa , Spain
- IKERBASQUE, Basque Foundation for Science , 48013 Bilbao , Spain
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19
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Smet MH, Breysem L, Mussen E, Bosmans H, Marshall NW, Cockmartin L. Visual grading analysis of digital neonatal chest phantom X-ray images: Impact of detector type, dose and image processing on image quality. Eur Radiol 2018; 28:2951-2959. [PMID: 29460076 DOI: 10.1007/s00330-017-5301-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 12/13/2017] [Accepted: 12/29/2017] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To evaluate the impact of digital detector, dose level and post-processing on neonatal chest phantom X-ray image quality (IQ). METHODS A neonatal phantom was imaged using four different detectors: a CR powder phosphor (PIP), a CR needle phosphor (NIP) and two wireless CsI DR detectors (DXD and DRX). Five different dose levels were studied for each detector and two post-processing algorithms evaluated for each vendor. Three paediatric radiologists scored the images using European quality criteria plus additional questions on vascular lines, noise and disease simulation. Visual grading characteristics and ordinal regression statistics were used to evaluate the effect of detector type, post-processing and dose on VGA score (VGAS). RESULTS No significant differences were found between the NIP, DXD and CRX detectors (p>0.05) whereas the PIP detector had significantly lower VGAS (p< 0.0001). Processing did not influence VGAS (p=0.819). Increasing dose resulted in significantly higher VGAS (p<0.0001). Visual grading analysis (VGA) identified a detector air kerma/image (DAK/image) of ~2.4 μGy as an ideal working point for NIP, DXD and DRX detectors. CONCLUSIONS VGAS tracked IQ differences between detectors and dose levels but not image post-processing changes. VGA showed a DAK/image value above which perceived IQ did not improve, potentially useful for commissioning. KEY POINTS • A VGA study detects IQ differences between detectors and dose levels. • The NIP detector matched the VGAS of the CsI DR detectors. • VGA data are useful in setting initial detector air kerma level. • Differences in NNPS were consistent with changes in VGAS.
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Affiliation(s)
- M H Smet
- Department of Radiology, University Hospital Leuven, Herestraat, 49, 3000 - Leuven, Louvain, Belgium.
| | - L Breysem
- Department of Radiology, University Hospital Leuven, Herestraat, 49, 3000 - Leuven, Louvain, Belgium
| | - E Mussen
- Department of Radiology, University Hospital Leuven, Herestraat, 49, 3000 - Leuven, Louvain, Belgium
| | - H Bosmans
- Department of Radiology, University Hospital Leuven, Herestraat, 49, 3000 - Leuven, Louvain, Belgium.,Medical Imaging Research Center, Medical Physics and Quality Assessment, Katholieke Universiteit Leuven, 3000 - Leuven, Louvain, Belgium
| | - N W Marshall
- Department of Radiology, University Hospital Leuven, Herestraat, 49, 3000 - Leuven, Louvain, Belgium.,Medical Imaging Research Center, Medical Physics and Quality Assessment, Katholieke Universiteit Leuven, 3000 - Leuven, Louvain, Belgium
| | - L Cockmartin
- Department of Radiology, University Hospital Leuven, Herestraat, 49, 3000 - Leuven, Louvain, Belgium
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An analytical approach to the light transport in columnar phosphors. Detector Optical Gain, angular distribution and the CsI:Tl paradigm. Phys Med 2017; 35:39-49. [PMID: 28242138 DOI: 10.1016/j.ejmp.2017.02.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Revised: 01/23/2017] [Accepted: 02/11/2017] [Indexed: 11/24/2022] Open
Abstract
PURPOSE An analytical model has been developed for the light propagation in columnar phosphors, based on the optical photon propagation physical and geometrical principles. METHODS This model accounts for the multiple reflections on the sides of the crystal column, as well as for the infinite forward and backward reflections of the propagated optical photon beams created in the crystal bulk. Additionally it considers the lateral propagated optical photon beams after multiple refractions from the neighbor columns and the optical photon attenuation inside the scintillator. The model was used to predict the Detector Optical Gain (DOG), and the angular distribution, of the columnar CsI:Tl scintillators, used in medical imaging. RESULTS The model was validated against CsI:Tl optical photon transmission published results and good agreement was observed. It was, also, found that the DOG is affected by the length of the columns, as well as the incident X-ray energy spectrum. The results of the angular distribution are in accordance with the theory that the longer crystal columns have more directional light distribution. CONCLUSIONS The results of DOG are in accordance with the use of short crystal columns for lower energies (mammography) and the use of long crystal columns for higher energies (general radiology). Angular distribution was found more directive for long crystal columns.
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Kuttig JD, Steiding C, Kolditz D, Hupfer M, Karolczak M, Kalender WA. Comparative investigation of the detective quantum efficiency of direct and indirect conversion detector technologies in dedicated breast CT. Phys Med 2015; 31:406-13. [DOI: 10.1016/j.ejmp.2015.03.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/13/2015] [Accepted: 03/16/2015] [Indexed: 10/23/2022] Open
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Intravenous flat-detector computed tomography angiography for symptomatic cerebral vasospasm following aneurysmal subarachnoid hemorrhage. ScientificWorldJournal 2014; 2014:315960. [PMID: 25383367 PMCID: PMC4212549 DOI: 10.1155/2014/315960] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 08/28/2014] [Accepted: 09/13/2014] [Indexed: 11/18/2022] Open
Abstract
The study evaluated the diagnostic accuracy of intravenous flat-detector computed tomography (IV FDCT) angiography in assessing hemodynamically significant cerebral vasospasm in patients with subarachnoid hemorrhage (SAH) with digital subtraction angiography (DSA) as the reference. DSA and IV FDCT were conducted concurrently in patients suspected of having symptomatic cerebral vasospasm postoperatively. The presence and severity of vasospasm were estimated according to location (proximal versus distal). Vasospasm >50% was defined as having hemodynamic significance. Vasospasms <30% were excluded from this analysis to avoid spectrum bias. Twenty-nine patients (311 vessel segments) were measured. The intra- and interobserver agreements were excellent for depicting vasospasm (k = 0.84 and 0.74, resp.). IV FDCT showed a sensitivity of 95.7%, specificity of 92.3%, positive predictive value of 93.6%, and negative predictive value of 94.7% for detecting vasospasm (>50%) with DSA as the reference. Bland-Altman plots revealed good agreement of assessing vasospasm between the two tests. The discrepancy of vasospasm severity was more noted in the distal location with high-severity. However, it was not statistically significant (Spearman's rank test; r = 0.15, P = 0.35). Therefore, IV FDCT could be a feasible noninvasive test to evaluate suspected significant vasospasm in SAH.
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Zhao C, Kanicki J. Amorphous In-Ga-Zn-O thin-film transistor active pixel sensor x-ray imager for digital breast tomosynthesis. Med Phys 2014; 41:091902. [DOI: 10.1118/1.4892382] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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Enríquez G, Piqueras J, Catalá A, Oliva G, Ruiz A, Ribas M, Duran C, Rodrigo C, Rodríguez E, Garriga V, Maristany T, García-Fontecha C, Baños J, Muchart J, Álava F. Optimización del estudio radiológico de la escoliosis. Med Clin (Barc) 2014; 143 Suppl 1:62-7. [DOI: 10.1016/j.medcli.2014.07.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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25
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Effect of radiation dose level on the detectability of pulmonary nodules in chest tomosynthesis. Eur Radiol 2014; 24:1529-36. [DOI: 10.1007/s00330-014-3182-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 04/02/2014] [Accepted: 04/08/2014] [Indexed: 12/21/2022]
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26
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Ferreira RI, Bahrami G, Isidor F, Wenzel A, Haiter-Neto F, Groppo FC. Detection of vertical root fractures by cone-beam computerized tomography in endodontically treated teeth with fiber-resin and titanium posts: an in vitro study. Oral Surg Oral Med Oral Pathol Oral Radiol 2013; 115:e49-57. [DOI: 10.1016/j.oooo.2012.06.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 06/13/2012] [Accepted: 06/18/2012] [Indexed: 10/27/2022]
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Pantos I, Koukorava C, Nirgianaki E, Carinou E, Tzanalaridou E, Efstathopoulos EP, Katritsis DG. Radiation exposure of the operator during cardiac catheter ablation procedures. RADIATION PROTECTION DOSIMETRY 2012; 150:306-311. [PMID: 22234422 DOI: 10.1093/rpd/ncr414] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Radiation exposure of the operator during cardiac catheter ablation procedures was assessed for an experienced cardiologist adopting various measures of radiation protection and utilised electroanatomic navigation. Chip thermoluminescent dosemeters were placed at the eyes, chest, wrists and legs of the operator. The ranges of fluoroscopy time and air kerma area product values associated with cardiac ablation procedures were wide (6.3-48.3 min and 1.7-80.3 Gy cm(2), respectively). The measured median radiation doses per procedure for each monitored position were 23.6 and 21.3 μSv to the left and right wrists, respectively, 25.3 and 30.4 μSv to the left and right legs, respectively. The doses to the eyes were below the minimum detectable dose of 9 μSv. The estimated median effective dose was 22.5 μSv. Considering the actual workload of the operator, the calculated annual doses to the hands, legs and eyes, as well as the annual effective dose, were all below the corresponding limits. The findings of this study indicate that cardiac ablation procedures performed at a modern laboratory do not impose a high radiation hazard to the operator when radiation protection measures are routinely adopted.
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Affiliation(s)
- I Pantos
- Department of Cardiology, Athens Euroclinic, Athens, Greece
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Comparison of Digital Flat-Panel Detector and Conventional Angiography Machines: Evaluation of Stent Detection Rates, Visibility Scores, and Dose-Area Products. AJR Am J Roentgenol 2012; 198:946-54. [DOI: 10.2214/ajr.11.7245] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Meier D, Wagenaar DJ, Chen S, Xu J, Yu J, Tsui BMW. A SPECT Camera for Combined MRI and SPECT for Small Animals. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH. SECTION A, ACCELERATORS, SPECTROMETERS, DETECTORS AND ASSOCIATED EQUIPMENT 2011; 652:731-734. [PMID: 21966076 DOI: 10.1016/j.nima.2013.05.174] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We describe an MR-compatible SPECT camera for small animals. The SPECT camera system can be inserted into the bore of a state-of-the-art MRI system and allows researchers to acquire tomographic images from a mouse in-vivo with the MRI and the SPECT acquiring simultaneously. The SPECT system provides functional information, while MRI provides anatomical information. Until today it was impossible to operate conventional SPECT inside the MRI because of mutual interference. The new SPECT technology is based on semiconductor radiation sensors (CZT, ASICs), and it fits into conventional high field MRI systems with a minimum 12-cm bore size. The SPECT camera has an MR-compatible multi-pinhole collimator for mice with a ø25-mm field-of-view. For the work reported here we assembled a prototype SPECT camera system and acquired SPECT and MRI data from radioactive sources and resolution phantoms using the camera outside and inside the MRI.
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Affiliation(s)
- D Meier
- Gamma Medica - Ideas (Norway) AS, Martin Linges Vei 25, Snarøya, POB 1, N-1330 Fornebu, Norway
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Prieto C, Vano E, Fernández JM, Martínez D, Sánchez R. Increases in patient doses need to be avoided when upgrading interventional cardiology systems to flat detectors. RADIATION PROTECTION DOSIMETRY 2011; 147:83-85. [PMID: 21733865 DOI: 10.1093/rpd/ncr273] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The aim of this study was to evaluate patient doses in two interventional cardiology laboratories over a period of 1 y in which the imaging devices were changed from image intensifier (II) to flat detector (FD). Dosimetric data from a total of 1040 coronary angiography (CA) procedures and 1087 percutaneous transluminal coronary angioplasty (PTCA) procedures were gathered. During the period studied with II imaging, median values of dose area product were 28 Gy cm(2) for CA and 57 Gy cm(2) for PTCA. In the first half of the year with FD imaging, median values were 37 Gy cm(2) for CA and 89 Gy cm(2) for PTCA. A significant increase in patient doses was noticed in the early stages of use of FD technology for imaging IC procedures, while fluoroscopy time and number of images remained similar. A careful setting of the X-ray systems, after upgrading the imaging system, is essential to avoid unjustified increases in patient doses.
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Affiliation(s)
- C Prieto
- Medical Physics Service San Carlos University Hospital, 28040 Madrid, Spain.
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Combaz X, Levrier O, Moritz J, Mancini J, Regis J, Bartoli J, Girard N. Three-dimensional rotational angiography in the assessment of the angioarchitecture of brain arteriovenous malformations. J Neuroradiol 2011; 38:167-74. [DOI: 10.1016/j.neurad.2010.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2010] [Revised: 08/25/2010] [Accepted: 08/27/2010] [Indexed: 10/18/2022]
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Kasap S, Frey JB, Belev G, Tousignant O, Mani H, Greenspan J, Laperriere L, Bubon O, Reznik A, DeCrescenzo G, Karim KS, Rowlands JA. Amorphous and polycrystalline photoconductors for direct conversion flat panel x-ray image sensors. SENSORS 2011; 11:5112-57. [PMID: 22163893 PMCID: PMC3231396 DOI: 10.3390/s110505112] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 04/25/2011] [Accepted: 05/04/2011] [Indexed: 11/29/2022]
Abstract
In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs). We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se) has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE). Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF) and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI2 and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the HARP has been recently demonstrated with excellent avalanche gains; the latter is expected to lead to a number of novel imaging device applications that would be quantum noise limited. While passive pixel sensors use one TFT (thin film transistor) as a switch at the pixel, active pixel sensors (APSs) have two or more transistors and provide gain at the pixel level. The advantages of APS based x-ray imagers are also discussed with examples.
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Affiliation(s)
- Safa Kasap
- Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada; E-Mails: (J.B.F.); (G.B.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-306-966-5390; Fax: +1-306-966-5407
| | - Joel B. Frey
- Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada; E-Mails: (J.B.F.); (G.B.)
| | - George Belev
- Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada; E-Mails: (J.B.F.); (G.B.)
| | - Olivier Tousignant
- Anrad Corporation, 4950 rue Lévy, Saint-Laurent, QC, H4R 2P1, Canada; E-Mails: (O.T.); (H.M.); (J.G.); (L.L.)
| | - Habib Mani
- Anrad Corporation, 4950 rue Lévy, Saint-Laurent, QC, H4R 2P1, Canada; E-Mails: (O.T.); (H.M.); (J.G.); (L.L.)
| | - Jonathan Greenspan
- Anrad Corporation, 4950 rue Lévy, Saint-Laurent, QC, H4R 2P1, Canada; E-Mails: (O.T.); (H.M.); (J.G.); (L.L.)
| | - Luc Laperriere
- Anrad Corporation, 4950 rue Lévy, Saint-Laurent, QC, H4R 2P1, Canada; E-Mails: (O.T.); (H.M.); (J.G.); (L.L.)
| | - Oleksandr Bubon
- Department of Physics, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada; E-Mails: (O.B.); (A.R.)
| | - Alla Reznik
- Department of Physics, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B 5E1, Canada; E-Mails: (O.B.); (A.R.)
- Thunder Bay Regional Research Institute, 980 Oliver Road, Thunder Bay, ON, P7B 6V4, Canada; E-Mails: (G.D.); (J.A.R.)
| | - Giovanni DeCrescenzo
- Thunder Bay Regional Research Institute, 980 Oliver Road, Thunder Bay, ON, P7B 6V4, Canada; E-Mails: (G.D.); (J.A.R.)
| | - Karim S. Karim
- Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada; E-Mail:
| | - John A. Rowlands
- Thunder Bay Regional Research Institute, 980 Oliver Road, Thunder Bay, ON, P7B 6V4, Canada; E-Mails: (G.D.); (J.A.R.)
- Imaging Research, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada
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Sakaguchi T, Katayama R, Morishita J, Sakai S, Kuroki H, Ohkubo S, Maeda T, Hayabuchi N. [Correlation between basic imaging properties and subjective evaluations of two digital radiographic X-ray systems based on direct-conversion flat panel detector]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2010; 66:1457-1466. [PMID: 21099176 DOI: 10.6009/jjrt.66.1457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The purpose of this study was to examine the correlation between the basic imaging properties of two digital radiographic X-ray systems with a direct conversion flat-panel detector and their image qualities, which were evaluated by the observer in hard copy and soft copy studies. The subjective image quality was evaluated and compared in terms of the low-contrast detectability and image sharpness in the two digital radiographic X-ray systems. We applied the radiographs of a contrast detail phantom to the evaluation of low-contrast detectability and analyzed the contrast detail diagrams. Finally, low-contrast detectability was evaluated by the image quality figure (IQF) calculated from the contrast detail diagrams. Also, the subjective image sharpness of human dry bones of two systems was examined and evaluated by the normalized-rank method. The results indicated that System A tended to provide superior subjective image quality compared to System B in both observer studies. We also found high correlations between IQFs and basic imaging properties, such as the noise power spectrum (NPS) and the noise equivalent quantum (NEQ). In conclusion, the low-contrast detectability of the two digital radiographic X-ray systems with a direct conversion flat-panel detector corresponded to the NPS and the NEQ in both outputs (soft copy and hard copy). On the other hand, the subjective image sharpness of human dry bones was affected by their noise properties.
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Affiliation(s)
- Taro Sakaguchi
- Center for Diagnostic Imaging, Kurume University Hospital
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Vano E, Ubeda C, Martinez LC, Leyton F, Miranda P. Paediatric interventional cardiology: flat detector versus image intensifier using a test object. Phys Med Biol 2010; 55:7287-97. [DOI: 10.1088/0031-9155/55/23/007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Kabir MZ, Chowdhury L, DeCrescenzo G, Tousignant O, Kasap SO, Rowlands JA. Effect of repeated x-ray exposure on the resolution of amorphous selenium based x-ray imagers. Med Phys 2010; 37:1339-49. [PMID: 20384271 DOI: 10.1118/1.3326947] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE A numerical model and the experimental methods to study the x-ray exposure dependent change in the modulation transfer function (MTF) of amorphous selenium (a-Se) based active matrix flat panel imagers (AMFPIs) are described. The physical mechanisms responsible for the x-ray exposure dependent change in MTF are also investigated. METHODS A numerical model for describing the x-ray exposure dependent MTF of a-Se based AMFPIs has been developed. The x-ray sensitivity and MTF of an a-Se AMFPI have been measured as a function of exposure. The instantaneous electric field and free and trapped carrier distributions in the photoconductor layer are obtained by numerically solving the Poisson's equation, continuity equations, and trapping rate equations using the backward Euler finite difference method. From the trapped carrier distributions, a method for calculating the MTF due to incomplete charge collection is proposed. RESULTS The model developed in this work and the experimental data show a reasonably good agreement. The model is able to simultaneously predict the dependence of the sensitivity and MTF on accumulated exposure at different applied fields and bias polarities, with the same charge transport parameters that are typical of the particular a-Se photoconductive layer that is used in these AMFPIs. Under negative bias, the MTF actually improves with the accumulated x-ray exposure while the sensitivity decreases. The MTF enhancement with exposure decreases with increasing applied field. CONCLUSIONS The most prevalent processes that control the MTF under negative bias are the recombination of drifting holes with previously trapped electrons (electrons remain in deep traps due to their long release times compared with the time scale of the experiments) and the deep trapping of drifting holes and electrons.
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Affiliation(s)
- M Z Kabir
- Department of Electrical and Computer Engineering, Concordia University, 1455 de Maisonneuve W, Montreal, Quebec H3G 1M8, Canada.
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Digital breast tomosynthesis versus digital mammography: a clinical performance study. Eur Radiol 2009; 20:1545-53. [PMID: 20033175 DOI: 10.1007/s00330-009-1699-5] [Citation(s) in RCA: 175] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 10/14/2009] [Accepted: 11/14/2009] [Indexed: 10/20/2022]
Abstract
OBJECTIVE To compare the clinical performance of digital breast tomosynthesis (DBT) with that of full-field digital mammography (FFDM) in a diagnostic population. METHODS The study enrolled 200 consenting women who had at least one breast lesion discovered by mammography and/or ultrasound classified as doubtful or suspicious or probably malignant. They underwent tomosynthesis in one view [mediolateral oblique (MLO)] of both breasts at a dose comparable to that of standard screen-film mammography in two views [craniocaudal (CC) and MLO]. Images were rated by six breast radiologists using the BIRADS score. Ratings were compared with the truth established according to the standard of care and a multiple-reader multiple-case (MRMC) receiver-operating characteristic (ROC) analysis was performed. Clinical performance of DBT compared with that of FFDM was evaluated in terms of the difference between areas under ROC curves (AUCs) for BIRADS scores. RESULTS Overall clinical performance with DBT and FFDM for malignant versus all other cases was not significantly different (AUCs 0.851 vs 0.836, p = 0.645). The lower limit of the 95% CI or the difference between DBT and FFDM AUCs was -4.9%. CONCLUSION Clinical performance of tomosynthesis in one view at the same total dose as standard screen-film mammography is not inferior to digital mammography in two views.
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38
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Bogaert E, Bacher K, Lapere R, Thierens H. Does digital flat detector technology tip the scale towards better image quality or reduced patient dose in interventional cardiology? Eur J Radiol 2009; 72:348-53. [DOI: 10.1016/j.ejrad.2008.07.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Accepted: 07/28/2008] [Indexed: 11/28/2022]
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O'Brien B, Carroll W. The evolution of cardiovascular stent materials and surfaces in response to clinical drivers: a review. Acta Biomater 2009; 5:945-58. [PMID: 19111513 DOI: 10.1016/j.actbio.2008.11.012] [Citation(s) in RCA: 219] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 10/26/2008] [Accepted: 11/20/2008] [Indexed: 11/28/2022]
Abstract
This review examines cardiovascular stent materials from the perspective of a range of clinical drivers and the materials that have been developed in response to these drivers. The review is generally chronological and outlines how stent materials have evolved from initial basic stainless steel devices all the way through to the novel biodegradable devices currently being explored. Where appropriate, pre-clinical or clinical data that influenced decisions and selections along the way is referenced. Opinions are given as to the merit and direction of various ongoing and future developments.
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Affiliation(s)
- Barry O'Brien
- National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Ireland.
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Geijer H, Norrman E, Persliden J. Optimizing the tube potential for lumbar spine radiography with a flat-panel digital detector. Br J Radiol 2009; 82:62-8. [PMID: 19095816 DOI: 10.1259/bjr/56572915] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The purpose of this study was to find the optimal settings for lumbar spine radiography with a flat-panel detector. A CDRAD contrast-detail phantom was imaged at various tube potentials, system speeds and filtration settings. Factorial experiments yielded a range of optimized exposure settings, which were submitted to visual grading analysis with images of an Alderson phantom. The first optimized settings involved a system speed increase from 400 to 800. For anteroposterior projection, the optimal tube potential was reduced from the default of 77 kV to 60 kV to give the best image quality without increasing the effective dose, or to 66 kV to give the lowest dose without reducing image quality. For lateral projection, the tube potential was similarly reduced from the default of 90 kV to 70 kV or 77 kV. Visual grading analysis confirmed the results, with significantly better image quality when optimizing for image quality. The study thus shows that the tube potential can be reduced as long as the system speed is increased simultaneously. This leads to a lower effective dose and/or increased image quality depending on the settings chosen. The factorial experiments provided a powerful way to evaluate several parameters concomitantly.
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Affiliation(s)
- H Geijer
- Department of Radiology, Orebro University Hospital, Orebro, Sweden.
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Cowen AR, Davies AG, Sivananthan MU. The design and imaging characteristics of dynamic, solid-state, flat-panel x-ray image detectors for digital fluoroscopy and fluorography. Clin Radiol 2008; 63:1073-85. [PMID: 18774353 DOI: 10.1016/j.crad.2008.06.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Accepted: 06/04/2008] [Indexed: 10/21/2022]
Abstract
Dynamic, flat-panel, solid-state, x-ray image detectors for use in digital fluoroscopy and fluorography emerged at the turn of the millennium. This new generation of dynamic detectors utilize a thin layer of x-ray absorptive material superimposed upon an electronic active matrix array fabricated in a film of hydrogenated amorphous silicon (a-Si:H). Dynamic solid-state detectors come in two basic designs, the indirect-conversion (x-ray scintillator based) and the direct-conversion (x-ray photoconductor based). This review explains the underlying principles and enabling technologies associated with these detector designs, and evaluates their physical imaging characteristics, comparing their performance against the long established x-ray image intensifier television (TV) system. Solid-state detectors afford a number of physical imaging benefits compared with the latter. These include zero geometrical distortion and vignetting, immunity from blooming at exposure highlights and negligible contrast loss (due to internal scatter). They also exhibit a wider dynamic range and maintain higher spatial resolution when imaging over larger fields of view. The detective quantum efficiency of indirect-conversion, dynamic, solid-state detectors is superior to that of both x-ray image intensifier TV systems and direct-conversion detectors. Dynamic solid-state detectors are playing a burgeoning role in fluoroscopy-guided diagnosis and intervention, leading to the displacement of x-ray image intensifier TV-based systems. Future trends in dynamic, solid-state, digital fluoroscopy detectors are also briefly considered. These include the growth in associated three-dimensional (3D) visualization techniques and potential improvements in dynamic detector design.
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Affiliation(s)
- A R Cowen
- Division of Medical Physics, LXi_Research, The University of Leeds, Leeds, West Yorkshire, UK.
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Comparison between effective radiation dose of CBCT and MSCT scanners for dentomaxillofacial applications. Eur J Radiol 2008; 71:461-8. [PMID: 18639404 DOI: 10.1016/j.ejrad.2008.06.002] [Citation(s) in RCA: 332] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Revised: 04/30/2008] [Accepted: 06/03/2008] [Indexed: 11/22/2022]
Abstract
OBJECTIVES To compare the effective dose levels of cone beam computed tomography (CBCT) for maxillofacial applications with those of multi-slice computed tomography (MSCT). STUDY DESIGN The effective doses of 3 CBCT scanners were estimated (Accuitomo 3D, i-CAT, and NewTom 3G) and compared to the dose levels for corresponding image acquisition protocols for 3 MSCT scanners (Somatom VolumeZoom 4, Somatom Sensation 16 and Mx8000 IDT). The effective dose was calculated using thermoluminescent dosimeters (TLDs), placed in a Rando Alderson phantom, and expressed according to the ICRP 103 (2007) guidelines (including a separate tissue weighting factor for the salivary glands, as opposed to former ICRP guidelines). RESULTS Effective dose values ranged from 13 to 82 microSv for CBCT and from 474 to 1160 microSv for MSCT. CBCT dose levels were the lowest for the Accuitomo 3D, and highest for the i-CAT. CONCLUSIONS Dose levels for CBCT imaging remained far below those of clinical MSCT protocols, even when a mandibular protocol was applied for the latter, resulting in a smaller field of view compared to various CBCT protocols. Considering this wide dose span, it is of outmost importance to justify the selection of each of the aforementioned techniques, and to optimise the radiation dose while achieving a sufficient image quality. When comparing these results to previous dosimetric studies, a conversion needs to be made using the latest ICRP recommendations.
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Martinez LC, Vano E, Gutierrez F, Rodriguez C, Gilarranz R, Manzanas MJ. Patient doses from fluoroscopically guided cardiac procedures in pediatrics. Phys Med Biol 2007; 52:4749-59. [PMID: 17671333 DOI: 10.1088/0031-9155/52/16/003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Infants and children are a higher risk population for radiation cancer induction compared to adults. Although some values on pediatric patient doses for cardiac procedures have been reported, data to determine reference levels are scarce, especially when compared to those available for adults in diagnostic and therapeutic procedures. The aim of this study is to make a new contribution to the scarce published data in pediatric cardiac procedures and help in the determination of future dose reference levels. This paper presents a set of patient dose values, in terms of air kerma area product (KAP) and entrance surface air kerma (ESAK), measured in a pediatric cardiac catheterization laboratory equipped with a biplane x-ray system with dynamic flat panel detectors. Cardiologists were properly trained in radiation protection. The study includes 137 patients aged between 10 days and 16 years who underwent diagnostic catheterizations or therapeutic procedures. Demographic data and technical details of the procedures were also gathered. The x-ray system was submitted to a quality control programme, including the calibration of the transmission ionization chamber. The age distribution of the patients was 47 for <1 year; 52 for 1-<5 years; 25 for 5-<10 years and 13 for 10-<16 years. Median values of KAP were 1.9, 2.9, 4.5 and 15.4 Gy cm(2) respectively for the four age bands. These KAP values increase by a factor of 8 when moving through the four age bands. The probability of a fatal cancer per fluoroscopically guided cardiac procedure is about 0.07%. Median values of ESAK for the four age bands were 46, 50, 56 and 163 mGy, which lie far below the threshold for deterministic effects on the skin. These dose values are lower than those published in previous papers.
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Affiliation(s)
- L C Martinez
- Medical Physics and Radiation Protection Service, 12 de Octubre University Hospital, Madrid, Spain.
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Nickoloff EL, Lu ZF, Dutta A, So J, Balter S, Moses J. Influence of flat-panel fluoroscopic equipment variables on cardiac radiation doses. Cardiovasc Intervent Radiol 2007; 30:169-76. [PMID: 17216374 DOI: 10.1007/s00270-006-0096-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE To assess the influence of physician-selectable equipment variables on the potential radiation dose reductions during cardiac catheterization examinations using modern imaging equipment. MATERIALS A modern bi-plane angiography unit with flat-panel image receptors was used. Patients were simulated with 15-30 cm of acrylic plastic. The variables studied were: patient thickness, fluoroscopy pulse rates, record mode frame rates, image receptor field-of-view (FoV), automatic dose control (ADC) mode, SID/SSD geometry setting, automatic collimation, automatic positioning, and others. RESULTS Patient radiation doses double for every additional 3.5-4.5 cm of soft tissue. The dose is directly related to the imaging frame rate; a decrease from 30 pps to 15 pps reduces the dose by about 50%. The dose is related to [(FoV)(-N )] where 2.0 < N < 3.0. Suboptimal positioning of the patient can nearly double the dose. The ADC system provides three selections that can vary the radiation level by 50%. For pediatric studies (2-5 years old), the selection of equipment variables can result in entrance radiation doses that range between 6 and 60 cGy for diagnostic cases and between 15 and 140 cGy for interventional cases. For adult studies, the equipment variables can produce entrance radiation doses that range between 13 and 130 cGy for diagnostic cases and between 30 and 400 cGy for interventional cases. CONCLUSIONS Overall dose reductions of 70-90% can be achieved with pediatric patients and about 90% with adult patients solely through optimal selection of equipment variables.
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Affiliation(s)
- Edward L Nickoloff
- Department of Radiology, College of Physicians and Surgeons, Columbia University and New York-Presbyterian Hospital, MHB 3-265, 177 Fort Washington Avenue, New York, NY 10032, USA.
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Körner M, Weber CH, Wirth S, Pfeifer KJ, Reiser MF, Treitl M. Advances in Digital Radiography: Physical Principles and System Overview. Radiographics 2007; 27:675-86. [PMID: 17495286 DOI: 10.1148/rg.273065075] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
During the past two decades, digital radiography has supplanted screen-film radiography in many radiology departments. Today, manufacturers provide a variety of digital imaging solutions based on various detector and readout technologies. Digital detectors allow implementation of a fully digital picture archiving and communication system, in which images are stored digitally and are available anytime. Image distribution in hospitals can now be achieved electronically by means of web-based technology with no risk of losing images. Other advantages of digital radiography include higher patient throughput, increased dose efficiency, and the greater dynamic range of digital detectors with possible reduction of radiation exposure to the patient. The future of radiography will be digital, and it behooves radiologists to be familiar with the technical principles, image quality criteria, and radiation exposure issues associated with the various digital radiography systems that are currently available.
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Affiliation(s)
- Markus Körner
- Department of Clinical Radiology, University Hospital Munich, Nussbaumstr 20, 80336 Munich, Germany.
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Ducote JL, Xu T, Molloi S. Dual-energy cardiac imaging: an image quality and dose comparison for a flat-panel detector and x-ray image intensifier. Phys Med Biol 2006; 52:183-96. [PMID: 17183135 DOI: 10.1088/0031-9155/52/1/012] [Citation(s) in RCA: 12] [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
This study presents a comparison of dual-energy imaging with an x-ray image intensifier and flat-panel detector for cardiac imaging. It also investigates if the wide dynamic range of the flat-panel detector can improve dual-energy image quality while reducing patient dose. Experimental contrast-to-noise (CNR) measurements were carried out in addition to simulation studies. Patient entrance exposure and system tube loading were also recorded. The studied contrast objects were calcium and iodine. System performance was quantified with a figure-of-merit (FOM) defined as the image CNR(2) over patient entrance exposure. The range of thickness studied was from 10 to 30 cm of Lucite (PMMA). Detector dose was initially set to 140 nGy (16 microR)/frame. The high-energy 120 kVp beam was filtered by an additional 0.8 mm silver filter. Keeping the same filament current, the kVp for the low-energy beam was adjusted as a function of thickness until 140 nGy was achieved. System performance was found to be similar for both systems, with the x-ray image intensifier performing better at lower thicknesses and the flat-panel detector performing better at higher thicknesses. This requirement of fixed detector entrance exposure was then relaxed and the kVp for the low-energy beam was allowed to vary while the mAs of the x-ray tube remained fixed to study changes in dual-energy image quality, patient dose and FOM with the flat-panel detector. It was found that as the kVp for the low-energy beam was reduced, system performance would rise until reaching a maximum while simultaneously lowering patient exposure. Suggested recommendations for optimal dual-energy imaging implementation are also provided.
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Affiliation(s)
- Justin L Ducote
- Department of Radiological Sciences, Medical Sciences I, B-140, University of California, Irvine, CA 92697, USA
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Davies AG, Cowen AR, Kengyelics SM, Moore J, Sivananthan MU. Do flat detector cardiac X-ray systems convey advantages over image-intensifier-based systems? Study comparing X-ray dose and image quality. Eur Radiol 2006; 17:1787-94. [PMID: 17115166 DOI: 10.1007/s00330-006-0458-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Revised: 06/21/2006] [Accepted: 08/25/2006] [Indexed: 11/25/2022]
Abstract
The recent introduction of "flat-panel detector" (FD)-based cardiac catheterisation laboratories should offer improvements in image quality and/or dose efficiency over X-ray systems of conventional design. We compared three X-ray systems, one image-intensifier (II)-based system (system A), and two FD-based designs (systems B and C), assessing their image quality and dose efficiency. Phantom measurements were performed to assess dose rates in fluoroscopy and cine acquisition. Phantom dose rates were broadly similar for all systems, with all systems classified as offering "low" dose rates in fluoroscopy on standard phantoms. Patient X-ray dose rate and subjective image quality was assessed for 90 patients. Dose area product (DAP) rates were similar for all systems, except system C, which had a lower DAP rate in fluoroscopy. In terms of subjective image quality, the order of preference was (best to worst): system C, system A, system B. This study indicates that the use of an FD detector does not infer an automatic improvement in image quality or dose efficiency over II based designs. Specification and configuration of all of the components in the X-ray system contribute to the dose levels used and image quality achieved.
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Fahrig R, Dixon R, Payne T, Morin RL, Ganguly A, Strobel N. Dose and image quality for a cone-beam C-arm CT system. Med Phys 2006; 33:4541-50. [PMID: 17278805 DOI: 10.1118/1.2370508] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
We assess dose and image quality of a state-of-the-art angiographic C-arm system (Axiom Artis dTA, Siemens Medical Solutions, Forchheim, Germany) for three-dimensional neuro-imaging at various dose levels and tube voltages and an associated measurement method. Unlike conventional CT, the beam length covers the entire phantom, hence, the concept of computed tomography dose index (CTDI) is not the metric of choice, and one can revert to conventional dosimetry methods by directly measuring the dose at various points using a small ion chamber. This method allows us to define and compute a new dose metric that is appropriate for a direct comparison with the familiar CTDIw of conventional CT. A perception study involving the CATPHAN 600 indicates that one can expect to see at least the 9 mm inset with 0.5% nominal contrast at the recommended head-scan dose (60 mGy) when using tube voltages ranging from 70 kVp to 125 kVp. When analyzing the impact of tube voltage on image quality at a fixed dose, we found that lower tube voltages gave improved low contrast detectability for small-diameter objects. The relationships between kVp, image noise, dose, and contrast perception are discussed.
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Affiliation(s)
- Rebecca Fahrig
- Radiology, Stanford University, Lucas MRS Imaging Center 1201 Welch Rd., Rm. P-286, Palo Alto, California 94305, USA
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Gennaro G, di Maggio C. Dose comparison between screen/film and full-field digital mammography. Eur Radiol 2006; 16:2559-66. [PMID: 16733678 DOI: 10.1007/s00330-006-0314-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Revised: 04/05/2006] [Accepted: 04/24/2006] [Indexed: 11/26/2022]
Abstract
The study purpose was the comparison between doses delivered by a full-field digital mammography system and a screen/film mammography unit, both using the same type of X-ray tube. Exposure parameters and breast thickness were collected for 300 screen/film (GE Senographe DMR) and 296 digital mammograms (GE Senographe 2000D). The entrance surface air kerma (ESAK) was calculated from anode/filter combination, kV(p) and mAs values and breast thickness, by simulating spectra through a program based on a catalogue of experimental X-ray spectra. The average glandular dose (AGD) was also computed. Results showed an overall reduction of average glandular dose by 27% of digital over screen/film mammography. The dose saving was about 15% for thin and thick breasts, while it was between 30% and 40% for intermediate thicknesses. Full-field digital mammography dose reduction is allowed by wider dynamic range and higher efficiency of digital detector, which can be exposed at higher energy spectra than screen/film mammography, and by the separation between acquisition and displaying processes.
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Affiliation(s)
- Gisella Gennaro
- Department of Oncological and Surgical Sciences, Padua University, via Gattamelata 64, 35128, Padua, Italy.
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