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Feng T, Zhou Z, An Y, Chen L, Fu Y, Zhou S, Wang N, Zheng J, Sun C. Large-Area Transparent Antimony-Based Perovskite Glass for High-Resolution X-ray Imaging. ACS NANO 2024; 18:16715-16725. [PMID: 38876985 DOI: 10.1021/acsnano.4c01761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2024]
Abstract
Nonlead low-dimensional halide perovskites attract considerable attention as X-ray scintillators. However, most scintillation screens exhibit pronounced light scattering, which detrimentally reduces the quality of X-ray imaging. Herein, we employed a simple and straightforward solvent-free melt-quenching method to fabricate a large-area zero-dimension (0D) antimony-based perovskite transparent medium, namely (C20H20P)2SbCl5 (C20H20P+ = ethyltriphenylphosphine). The transparency is due to the large steric hindrance of C20H20P+, which hinders the formation of crystals during the quenching process, thus forming a glass with low refractive index and uniform structure. This medium exhibits a high transmittance exceeding 80% in the range of 450-800 nm and shows a large Stokes shift of 245 nm, thereby minimizing light scattering, mitigating self-absorption, and enhancing the clarity of X-ray imaging. Moreover, it exhibits a high radioluminescence light yield of ∼12,535 photons MeV-1 and displays a high X-ray spatial resolution of 30 lp mm-1 owing to its high transparency. This study presents an alternative candidate for achieving high-quality X-ray detection and extends the applicability of transparent perovskite scintillators.
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Affiliation(s)
- Tiao Feng
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zi'an Zhou
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yi'ni An
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Long Chen
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Yuhua Fu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Shuyun Zhou
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Nü Wang
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, Beijing Key Laboratory of Bio-inspired Energy Materials and Devices, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, China
| | - Jinxiao Zheng
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Chenghua Sun
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
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2
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Ghosh J, O’Neill J, Masteghin MG, Braddock I, Crean C, Dorey R, Salway H, Anaya M, Reiss J, Wolfe D, Sellin P. Surfactant-Dependent Bulk Scale Mechanochemical Synthesis of CsPbBr 3 Nanocrystals for Plastic Scintillator-Based X-ray Imaging. ACS APPLIED NANO MATERIALS 2023; 6:14980-14990. [PMID: 37649835 PMCID: PMC10463220 DOI: 10.1021/acsanm.3c02531] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 07/21/2023] [Indexed: 09/01/2023]
Abstract
We report a facile, solvent-free surfactant-dependent mechanochemical synthesis of highly luminescent CsPbBr3 nanocrystals (NCs) and study their scintillation properties. A small amount of surfactant oleylamine (OAM) plays an important role in the two-step ball milling method to control the size and emission properties of the NCs. The solid-state synthesized perovskite NCs exhibit a high photoluminescence quantum yield (PLQY) of up to 88% with excellent stability. CsPbBr3 NCs capped with different amounts of surfactant were dispersed in toluene and mixed with polymethyl methacrylate (PMMA) polymer and cast into scintillator discs. With increasing concentration of OAM during synthesis, the PL yield of CsPbBr3/PMMA nanocomposite was increased, which is attributed to reduced NC aggregation and PL quenching. We also varied the perovskite loading concentration in the nanocomposite and studied the resulting emission properties. The most intense PL emission was observed from the 2% perovskite-loaded disc, while the 10% loaded disc exhibited the highest radioluminescence (RL) emission from 50 kV X-rays. The strong RL yield may be attributed to the deep penetration of X-rays into the composite, combined with the large interaction cross-section of the X-rays with the high-Z atoms within the NCs. The nanocomposite disc shows an intense RL emission peak centered at 536 nm and a fast RL decay time of 29.4 ns. Further, we have demonstrated the X-ray imaging performance of a 10% CsPbBr3 NC-loaded nanocomposite disc.
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Affiliation(s)
- Joydip Ghosh
- Department
of Physics, University of Surrey, Guildford GU2 7XH, U.K.
| | - Joseph O’Neill
- Department
of Physics, University of Surrey, Guildford GU2 7XH, U.K.
| | - Mateus G. Masteghin
- Advanced
Technology Institute, University of Surrey, Guildford GU2 7XH, U.K.
| | - Isabel Braddock
- Department
of Physics, University of Surrey, Guildford GU2 7XH, U.K.
| | - Carol Crean
- Department
of Chemistry, University of Surrey, Guildford GU2 7XH, U.K.
| | - Robert Dorey
- School
of Mechanical Engineering Sciences, University
of Surrey, Guildford GU2 7XH, U.K.
| | - Hayden Salway
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, U.K.
| | - Miguel Anaya
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, U.K.
- Departamento
Física de la Materia Condensada, Instituto de Ciencia
de Materiales de Sevilla, Universidad de
Sevilla−CSIC, Avenida Reina Mercedes SN, Sevilla 41012, Spain
| | - Justin Reiss
- Applied
Research
Laboratory, Materials Science and Engineering Department, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Douglas Wolfe
- Applied
Research
Laboratory, Materials Science and Engineering Department, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Paul Sellin
- Department
of Physics, University of Surrey, Guildford GU2 7XH, U.K.
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Yao SY, Li H, Zhou M, Wang TC, Yu X, Xu YS, Yi JH, Qiu JB, Yu J, Xu XH. Visualization of X-rays with an Ultralow Detection Limit via Zero-Dimensional Perovskite Scintillators. ACS APPLIED MATERIALS & INTERFACES 2022; 14:56957-56962. [PMID: 36516318 DOI: 10.1021/acsami.2c15902] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
X-rays play an extremely significant role in medical diagnosis, safety testing, scientific research, and other practical applications. However, as the main sources of radioactive pollution, the hazard of X-rays to human health and the environment has been a major concern. Herein, the explored perovskite scintillator of Cs2Zr1-xPbxCl6 in this work exhibits an ultrahigh radioluminescence intensity owing to the enhanced X-ray absorption for the introduction of Pb2+ ions. The Cs2Zr1-xPbxCl6 crystals are demonstrated as efficient scintillators with a self-trapped exciton emission and extremely high steady-state light yield (∼101,944 photons meV-1). This fascinating scintillator provides a convenient visual tool for X-ray detection even for an indoor lighting environment, reaching a low detection limit of ∼14.2 nGy·s-1, which is about 1/387 of the typical medical imaging dose (5.5 μGy·s-1). Moreover, X-ray imaging with a high resolution of 16.6 lp·mm-1 is achieved with the as-explored Cs2Zr1-xPbxCl6 scintillator film. Herein, the Cs2Zr1-xPbxCl6 scintillator provides a feasible strategy for X-ray monitoring in the field of biomedicine, high-energy physics, national security, and other applications.
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Affiliation(s)
- Shu-Yi Yao
- Faculty of Materials Science and Engineering, Key Laboratory of Advanced Materials of Yunnan Province, Kunming University of Science and Technology, Kunming 650093, Yunnan, P. R. China
| | - Hao Li
- Faculty of Materials Science and Engineering, Key Laboratory of Advanced Materials of Yunnan Province, Kunming University of Science and Technology, Kunming 650093, Yunnan, P. R. China
| | - Min Zhou
- College of Physical Science and Technology, Institute of Optoelectronic Technology, Yangzhou University, Yangzhou 225002, Jiangsu, P. R. China
| | - Tian-Chi Wang
- Faculty of Materials Science and Engineering, Key Laboratory of Advanced Materials of Yunnan Province, Kunming University of Science and Technology, Kunming 650093, Yunnan, P. R. China
| | - Xue Yu
- School of Mechanical Engineering, Institute for Advanced Materials Deformation and Damage from Multi-Scale, Chengdu University, Chengdu 610106, Sichuan, P. R. China
| | - Yin-Sheng Xu
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 430074 Wuhan, Hubei, P. R. China
| | - Jian-Hong Yi
- Faculty of Materials Science and Engineering, Key Laboratory of Advanced Materials of Yunnan Province, Kunming University of Science and Technology, Kunming 650093, Yunnan, P. R. China
| | - Jian-Bei Qiu
- Faculty of Materials Science and Engineering, Key Laboratory of Advanced Materials of Yunnan Province, Kunming University of Science and Technology, Kunming 650093, Yunnan, P. R. China
| | - Jie Yu
- Faculty of Materials Science and Engineering, Key Laboratory of Advanced Materials of Yunnan Province, Kunming University of Science and Technology, Kunming 650093, Yunnan, P. R. China
| | - Xu-Hui Xu
- Faculty of Materials Science and Engineering, Key Laboratory of Advanced Materials of Yunnan Province, Kunming University of Science and Technology, Kunming 650093, Yunnan, P. R. China
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4
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Wu X, Guo Z, Zhu S, Zhang B, Guo S, Dong X, Mei L, Liu R, Su C, Gu Z. Ultrathin, Transparent, and High Density Perovskite Scintillator Film for High Resolution X-Ray Microscopic Imaging. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200831. [PMID: 35478488 PMCID: PMC9189653 DOI: 10.1002/advs.202200831] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/27/2022] [Indexed: 06/02/2023]
Abstract
Inorganic perovskite quantum dots CsPbX3 (X = Cl, Br, and I) has recently received extensive attention as a new promising class of X-ray scintillators. However, relatively low light yield (LY) of CsPbX3 and strong optical scattering of the thick opaque scintillator film restrict their practical applications for high-resolution X-ray microscopic imaging. Here, the Ce3+ ion doped CsPbBr3 nanocrystals (NCs) with enhanced LY and stability are obtained and then the ultrathin (30 µm) and transparent scintillator films with high density are prepared by a suction filtration method. The small amount Ce3+ dopant greatly enhances the LY of CsPbBr3 NCs (about 33 000 photons per MeV), which is much higher than that of bare CsPbBr3 NCs. Moreover, the scintillator films made by these NCs with high density realize a high spatial resolution of 862 nm thanks to its thin and transparent feature, which is so far a record resolution for perovskite scintillator-based X-ray microscopic imaging. This strategy not only provides a simple way to increase the resolution down to nanoscale but also extends the application of as-prepared CsPbBr3 scintillator for high resolution X-ray microscopic imaging.
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Affiliation(s)
- Xiaochen Wu
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in NanoscienceInstitute of High Energy Physics and National Center for Nanoscience and TechnologyChinese Academy of SciencesBeijing100049China
- College of Mechanical and Electronic EngineeringShandong University of Science and TechnologyQingdao266590China
| | - Zhao Guo
- Fujian Key Laboratory of Translational Research in Cancer and Neurodegenerative DiseasesInstitute for Translational MedicineThe School of Basic Medical SciencesFujian Medical UniversityFuzhou350122China
| | - Shuang Zhu
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in NanoscienceInstitute of High Energy Physics and National Center for Nanoscience and TechnologyChinese Academy of SciencesBeijing100049China
- Center of Materials Science and Optoelectronics EngineeringCollege of Materials Science and Optoelectronic TechnologyUniversity of Chinese Academy of SciencesBeijing100049China
| | - Bingbing Zhang
- Beijing Synchrotron Radiation FacilityInstitute of High Energy PhysicsChinese Academy of SciencesBeijing100049China
| | - Sumin Guo
- College of Mechanical and Electronic EngineeringShandong University of Science and TechnologyQingdao266590China
| | - Xinghua Dong
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in NanoscienceInstitute of High Energy Physics and National Center for Nanoscience and TechnologyChinese Academy of SciencesBeijing100049China
| | - Linqiang Mei
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in NanoscienceInstitute of High Energy Physics and National Center for Nanoscience and TechnologyChinese Academy of SciencesBeijing100049China
- Center of Materials Science and Optoelectronics EngineeringCollege of Materials Science and Optoelectronic TechnologyUniversity of Chinese Academy of SciencesBeijing100049China
| | - Ruixue Liu
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in NanoscienceInstitute of High Energy Physics and National Center for Nanoscience and TechnologyChinese Academy of SciencesBeijing100049China
| | - Chunjian Su
- College of Mechanical and Electronic EngineeringShandong University of Science and TechnologyQingdao266590China
| | - Zhanjun Gu
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in NanoscienceInstitute of High Energy Physics and National Center for Nanoscience and TechnologyChinese Academy of SciencesBeijing100049China
- Center of Materials Science and Optoelectronics EngineeringCollege of Materials Science and Optoelectronic TechnologyUniversity of Chinese Academy of SciencesBeijing100049China
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5
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Ma J, Zhu W, Lei L, Deng D, Hua Y, Yang YM, Xu S, Prasad PN. Highly Efficient NaGdF 4:Ce/Tb Nanoscintillator with Reduced Afterglow and Light Scattering for High-Resolution X-ray Imaging. ACS APPLIED MATERIALS & INTERFACES 2021; 13:44596-44603. [PMID: 34516086 DOI: 10.1021/acsami.1c14503] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Scintillation-based X-ray excited optical luminescence (XEOL) imaging shows great potential applications in the fields of industrial security inspection and medical diagnosis. It is still a great challenge to achieve scintillators simultaneously with low toxicity, high stability, strong XEOL intensity, and weak afterglow as well as simple device processibility with weak light scattering. Herein, we introduce ethylenediaminetetraacetate (EDTA)-capped NaGdF4:10Ce/18Tb nanoparticles (NPs) as a highly sensitive nanoscintillator, which meets all of the abovementioned challenges. These NPs show comparable XEOL intensity to the commercial CsI (Tl) single crystal in the green region. We propose a mechanism that involves a new electron-captured path by Ce3+ ions and the promotion of energy migration from a trap center to surface quenchers via a Gd3+ sublattice, which greatly reduces the population in traps to produce significant reduction of afterglow. Moreover, by employing an ultrathin transparent NaGdF4:10Ce/18Tb film (0.045 mm) as a nanoscintillator screen for XEOL imaging, a high spatial resolution of 18.6 lp mm-1 is realized owing to the greatly limited optical scattering, which is superior to the commercial CsI (TI) scintillator and most reported lead halide perovskites. We demonstrate that doping Ce3+ ions can greatly limit X-ray-activated afterglow, enabling to use an ultrathin transparent fluoride NP-based nanoscintillator screen for high-quality XEOL imaging of various objects such as an electronics chip and biological tissue.
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Affiliation(s)
- Jinjing Ma
- College of Optical and Electronic Technology, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Wenjuan Zhu
- College of Optical Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310018, China
| | - Lei Lei
- College of Optical and Electronic Technology, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Degang Deng
- College of Optical and Electronic Technology, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Youjie Hua
- College of Optical and Electronic Technology, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Yang Michael Yang
- College of Optical Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310018, China
| | - Shiqing Xu
- College of Optical and Electronic Technology, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Paras N Prasad
- Institute for Lasers, Photonics, and Biophotonics and Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
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6
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Zhu W, Ma W, Su Y, Chen Z, Chen X, Ma Y, Bai L, Xiao W, Liu T, Zhu H, Liu X, Liu H, Liu X, Yang Y(M. Low-dose real-time X-ray imaging with nontoxic double perovskite scintillators. LIGHT, SCIENCE & APPLICATIONS 2020; 9:112. [PMID: 32637079 PMCID: PMC7327019 DOI: 10.1038/s41377-020-00353-0] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 06/12/2020] [Accepted: 06/17/2020] [Indexed: 05/03/2023]
Abstract
X-rays are widely used in probing inside information nondestructively, enabling broad applications in the medical radiography and electronic industries. X-ray imaging based on emerging lead halide perovskite scintillators has received extensive attention recently. However, the strong self-absorption, relatively low light yield and lead toxicity of these perovskites restrict their practical applications. Here, we report a series of nontoxic double-perovskite scintillators of Cs2Ag0.6Na0.4In1-yBiyCl6. By controlling the content of the heavy atom Bi3+, the X-ray absorption coefficient, radiative emission efficiency, light yield and light decay were manipulated to maximise the scintillator performance. A light yield of up to 39,000 ± 7000 photons/MeV for Cs2Ag0.6Na0.4In0.85Bi0.15Cl6 was obtained, which is much higher than that for the previously reported lead halide perovskite colloidal CsPbBr3 (21,000 photons/MeV). The large Stokes shift between the radioluminescence (RL) and absorption spectra benefiting from self-trapped excitons (STEs) led to a negligible self-absorption effect. Given the high light output and fast light decay of this scintillator, static X-ray imaging was attained under an extremely low dose of ∼1 μGyair, and dynamic X-ray imaging of finger bending without a ghosting effect was demonstrated under a low-dose rate of 47.2 μGyair s-1. After thermal treatment at 85 °C for 50 h followed by X-ray irradiation for 50 h in ambient air, the scintillator performance in terms of the RL intensity and X-ray image quality remained almost unchanged. Our results shed light on exploring highly competitive scintillators beyond the scope of lead halide perovskites, not only for avoiding toxicity but also for better performance.
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Affiliation(s)
- Wenjuan Zhu
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang China
| | - Wenbo Ma
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang China
| | - Yirong Su
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang China
| | - Zeng Chen
- Center for Chemistry of High-Performance & Novel Materials, department of Chemistry, Zhejiang University, Hangzhou, Zhejiang China
| | - Xinya Chen
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang China
| | - Yaoguang Ma
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang China
| | - Lizhong Bai
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang China
| | - Wenge Xiao
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang China
| | - Tianyu Liu
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang China
| | - Haiming Zhu
- Center for Chemistry of High-Performance & Novel Materials, department of Chemistry, Zhejiang University, Hangzhou, Zhejiang China
| | - Xiaofeng Liu
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang China
| | - Huafeng Liu
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang China
| | - Xu Liu
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang China
| | - Yang (Michael) Yang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang China
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Volken W, Zulliger MA, Koller B, Manser P, Fix MK. Investigation on the resolution of a micro cone beam CT scanner scintillating detector using Monte Carlo methods. Phys Med 2018; 53:17-24. [PMID: 30241750 DOI: 10.1016/j.ejmp.2018.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 06/13/2018] [Accepted: 08/05/2018] [Indexed: 11/19/2022] Open
Abstract
The impact of several physical quantities on the spatial resolution of an X-ray scintillating pixel detector for a micro cone beam CT (µCBCT) is investigated and discussed. The XtremeCT from SCANCO Medical AG was simulated using the EGSnrc/EGS++ Monte Carlo (MC) framework and extensively benchmarked in a previous work. The resolution of the detector was determined by simulating a titanium knife-edge to obtain the edge spread function (ESF) and the modulation transfer function (MTF). Propagation of the scintillation light through the scintillator and its coupling into the fiber optics system was taken into account. The contribution of particles scattered in the main scanner components to the detector signal is very low and does not affect the spatial resolution of the detector. The resolution obtained from the energy deposition in the scintillator without any blurring due to the propagation of the scintillation light into the fiber optics array was 31 µm. By assuming isotropic light propagation in the scintillator, the resolution degraded to 360 µm. A simple light propagation model taking into account the impact of the scintillator's columnar microstructures was developed and compared with the MANTIS Monte Carlo simulation package. By reducing the width of the model's light propagation kernel by a factor of 2 compared to the isotropic case, the detector resolution can be improved to 83 µm, which corresponds well to the measured resolution of 86 µm. The resolution of the detector is limited mainly by the propagation of the scintillation light through the scintillator layer. It offers the greatest potential to improve the resolution of the µCBCT imaging system.
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Affiliation(s)
- W Volken
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern, Switzerland
| | | | - B Koller
- SCANCO Medical AG, Brüttisellen, Switzerland
| | - P Manser
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern, Switzerland
| | - M K Fix
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern, Switzerland.
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8
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Roncali E, Mosleh-Shirazi MA, Badano A. Modelling the transport of optical photons in scintillation detectors for diagnostic and radiotherapy imaging. Phys Med Biol 2017; 62:R207-R235. [PMID: 28976914 PMCID: PMC5739055 DOI: 10.1088/1361-6560/aa8b31] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Computational modelling of radiation transport can enhance the understanding of the relative importance of individual processes involved in imaging systems. Modelling is a powerful tool for improving detector designs in ways that are impractical or impossible to achieve through experimental measurements. Modelling of light transport in scintillation detectors used in radiology and radiotherapy imaging that rely on the detection of visible light plays an increasingly important role in detector design. Historically, researchers have invested heavily in modelling the transport of ionizing radiation while light transport is often ignored or coarsely modelled. Due to the complexity of existing light transport simulation tools and the breadth of custom codes developed by users, light transport studies are seldom fully exploited and have not reached their full potential. This topical review aims at providing an overview of the methods employed in freely available and other described optical Monte Carlo packages and analytical models and discussing their respective advantages and limitations. In particular, applications of optical transport modelling in nuclear medicine, diagnostic and radiotherapy imaging are described. A discussion on the evolution of these modelling tools into future developments and applications is presented.
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Affiliation(s)
- Emilie Roncali
- Department of Biomedical Engineering, University of California Davis, Davis, USA
| | - Mohammad Amin Mosleh-Shirazi
- Medical Imaging Research Center, and, Physics Unit, Department of Radiotherapy and Oncology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz 71936-13311, Iran
| | - Aldo Badano
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20852, USA
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9
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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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10
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Howansky A, Peng B, Lubinsky AR, Zhao W. Deriving depth-dependent light escape efficiency and optical Swank factor from measured pulse height spectra of scintillators. Med Phys 2017; 44:847-860. [PMID: 28039881 DOI: 10.1002/mp.12083] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 11/28/2016] [Accepted: 12/22/2016] [Indexed: 01/04/2023] Open
Abstract
PURPOSE Pulse height spectroscopy has been used by investigators to deduce the imaging properties of scintillators. Pulse height spectra (PHS) are used to compute the Swank factor, which describes the variation in scintillator light output per x-ray interaction. The spread in PHS measured below the K-edge is related to the optical component of the Swank factor, i.e., variations in light escape efficiency from different depths of x-ray interaction in the scintillator, denoted ε¯(z). Optimizing scintillators for medical imaging applications requires understanding of these optical properties, as they determine tradeoffs between parameters such as x-ray absorption, light yield, and spatial resolution. This work develops a model for PHS acquisition such that the effect of measurement uncertainty can be removed. This method allows ε¯(z) to be quantified on an absolute scale and permits more accurate estimation of the optical Swank factor of scintillators. METHODS The pulse height spectroscopy acquisition chain was modeled as a linear system of stochastic gain stages. Analytical expressions were derived for signal and noise propagation through the PHS chain, accounting for deterministic and stochastic aspects of x-ray absorption, scintillation, and light detection with a photomultiplier tube. The derived expressions were used to calculate PHS of thallium-doped cesium iodide (CsI) scintillators using parameters that were measured, calculated, or known from literature. PHS were measured at 25 and 32 keV of CsI samples designed with an optically reflective or absorptive backing, with or without a fiber-optic faceplate (FOP), and with thicknesses ranging from 150-1000 μm. Measured PHS were compared with calculated PHS, then light escape model parameters were varied until measured and modeled results reached agreement. Resulting estimates of ε¯(z) were used to calculate each scintillator's optical Swank factor. RESULTS For scintillators of the same optical design, only minor differences in light escape efficiency were observed between samples with different thickness. As thickness increased, escape efficiency decreased by up to 20% for interactions furthest away from light collection. Optical design (i.e., backing and FOP) predominantly affected the magnitude and relative variation in ε¯(z). Depending on interaction depth and scintillator thickness, samples with an absorptive backing and FOP were estimated to yield 4.1-13.4 photons/keV. Samples with a reflective backing and FOP yielded 10.4-18.4 keV-1 , while those with a reflective backing and no FOP yielded 29.5-52.0 keV-1 . Optical Swank factors were approximately 0.9 and near-unity in samples featuring an absorptive or reflective backing, respectively. CONCLUSIONS This work uses a modeling approach to remove the noise introduced by the measurement apparatus from measured PHS. This method allows absolute quantification of ε¯(z) and more accurate estimation of the optical Swank factor of scintillators. The method was applied to CsI scintillators with different thickness and optical design, and determined that optical design more strongly affects ε¯(z) and Swank factor than differences in CsI thickness. Despite large variations in ε¯(z) between optical designs, the Swank factor of all evaluated samples is above 0.9. Information provided by this methodology can help validate Monte Carlo simulations of structured CsI and optimize scintillator design for x-ray imaging applications.
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Affiliation(s)
- Adrian Howansky
- Department of Radiology, State University of New York at Stony Brook, Stony Brook, NY, 11790-8460, USA
| | - Boyu Peng
- Department of Radiology, State University of New York at Stony Brook, Stony Brook, NY, 11790-8460, USA
| | - Anthony R Lubinsky
- Department of Radiology, State University of New York at Stony Brook, Stony Brook, NY, 11790-8460, USA
| | - Wei Zhao
- Department of Radiology, State University of New York at Stony Brook, Stony Brook, NY, 11790-8460, USA
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