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Kim K, Cha BK, Jeong HW, Lee Y. Investigation of Deconvolution Method with Adaptive Point Spread Function Based on Scintillator Thickness in Wavelet Domain. Bioengineering (Basel) 2024; 11:330. [PMID: 38671752 PMCID: PMC11048213 DOI: 10.3390/bioengineering11040330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 03/25/2024] [Accepted: 03/26/2024] [Indexed: 04/28/2024] Open
Abstract
In recent years, indirect digital radiography detectors have been actively studied to improve radiographic image performance with low radiation exposure. This study aimed to achieve low-dose radiation imaging with a thick scintillation detector while simultaneously obtaining the resolution of a thin scintillation detector. The proposed method was used to predict the optimal point spread function (PSF) between thin and thick scintillation detectors by considering image quality assessment (IQA). The process of identifying the optimal PSF was performed on each sub-band in the wavelet domain to improve restoration accuracy. In the experiments, the edge preservation index (EPI) values of the non-blind deblurred image with a blurring sigma of σ = 5.13 pixels and the image obtained with optimal parameters from the thick scintillator using the proposed method were approximately 0.62 and 0.76, respectively. The coefficient of variation (COV) values for the two images were approximately 1.02 and 0.63, respectively. The proposed method was validated through simulations and experimental results, and its viability is expected to be verified on various radiological imaging systems.
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Affiliation(s)
- Kyuseok Kim
- Department of Biomedical Engineering, Eulji University, 553, Sanseong-daero, Sujeong-gu, Seongnam-si 13135, Republic of Korea;
| | - Bo Kyung Cha
- Precision Medical Device Research Center, Korea Electrotechnology Research Institute (KERI), 111 Hanggaul-ro, Sangnok-gu, Ansan-si 15588, Republic of Korea;
| | - Hyun-Woo Jeong
- Department of Biomedical Engineering, Eulji University, 553, Sanseong-daero, Sujeong-gu, Seongnam-si 13135, Republic of Korea;
| | - Youngjin Lee
- Department of Radiological Science, Gachon University, Incheon 21936, Republic of Korea
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2
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Edmund E, Kamuzora M, Muhogora W, Ngoya P, Muhulo A, Amirali A, Makoba A, Ngoye W, Ngaile J, Majatta S, Ngulimi M, Mwambinga S, Kaijage T. Radiation dose to breast during digital mammography in Tanzania. RADIATION PROTECTION DOSIMETRY 2024; 200:409-416. [PMID: 38196028 DOI: 10.1093/rpd/ncad316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 11/07/2023] [Accepted: 12/07/2023] [Indexed: 01/11/2024]
Abstract
The aim of this study was to evaluate the mean glandular dose (MGD), to assess the potential for optimization, and to propose diagnostic reference levels (DRLs). MGD was estimated from air kerma measurements and patient information collected during mammography examinations. The 75th percentile values were determined as the third quartile of the median MGD values for all hospitals, and DRLs set as 75th percentile of MGD values. The estimated median values of MGD ranged from 1.5 to 3.9 mGy for craniocaudal projection for median range of 15-59 mm compressed breast thickness (CBT). For a CBT range of 15-63 mm, the median MGD value was 1.5-5.1 mGy for medio-lateral oblique projection. Comparison with other studies showed that the MGD values obtained in this study were relatively high. The magnitude and wide variation of the exposure parameters suggest existing potential for optimization. The training of radiology staff was identified as a top priority.
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Affiliation(s)
- Elisha Edmund
- Tanzania Atomic Energy Commission, Block J, Njiro, 23114 Arusha, Tanzania
| | - Mary Kamuzora
- Muhimbili National Hospital, Mloganzila, Kibamba, 16110 Dar es Salaam, Tanzania
| | - Wilbroad Muhogora
- Tanzania Atomic Energy Commission, Block J, Njiro, 23114 Arusha, Tanzania
| | - Patrick Ngoya
- Bugando Medical Centre, Makongoro Road, 33830 Mwanza, Tanzania
| | - Alex Muhulo
- Tanzania Atomic Energy Commission, Block J, Njiro, 23114 Arusha, Tanzania
| | - Assad Amirali
- Aga Khan Medical Centre, Baraka Obama Drive, 11101 Dar es Salaam, Tanzania
| | - Atumaini Makoba
- Tanzania Atomic Energy Commission, Block J, Njiro, 23114 Arusha, Tanzania
| | - Wilson Ngoye
- Tanzania Atomic Energy Commission, Block J, Njiro, 23114 Arusha, Tanzania
| | - Justin Ngaile
- Tanzania Atomic Energy Commission, Block J, Njiro, 23114 Arusha, Tanzania
| | - Salma Majatta
- Muhimbili National Hospital, Mloganzila, Kibamba, 16110 Dar es Salaam, Tanzania
| | - Miguta Ngulimi
- Tanzania Atomic Energy Commission, Block J, Njiro, 23114 Arusha, Tanzania
| | - Salome Mwambinga
- Tanzania Atomic Energy Commission, Block J, Njiro, 23114 Arusha, Tanzania
| | - Tunu Kaijage
- Tanzania Atomic Energy Commission, Block J, Njiro, 23114 Arusha, Tanzania
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3
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Dudipala KR, Le TH, Nie W, Hoye RLZ. Halide Perovskites and Their Derivatives for Efficient, High-Resolution Direct Radiation Detection: Design Strategies and Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2304523. [PMID: 37726105 DOI: 10.1002/adma.202304523] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Revised: 09/03/2023] [Indexed: 09/21/2023]
Abstract
The past decade has witnessed a rapid rise in the performance of optoelectronic devices based on lead-halide perovskites (LHPs). The large mobility-lifetime products and defect tolerance of these materials, essential for optoelectronics, also make them well-suited for radiation detectors, especially given the heavy elements present, which is essential for strong X-ray and γ-ray attenuation. Over the past decade, LHP thick films, wafers, and single crystals have given rise to direct radiation detectors that have outperformed incumbent technologies in terms of sensitivity (reported values up to 3.5 × 106 µC Gyair -1 cm-2 ), limit of detection (directly measured values down to 1.5 nGyair s-1 ), along with competitive energy and imaging resolution at room temperature. At the same time, lead-free perovskite-inspired materials (e.g., methylammonium bismuth iodide), which have underperformed in solar cells, have recently matched and, in some areas (e.g., in polarization stability), surpassed the performance of LHP detectors. These advances open up opportunities to achieve devices for safer medical imaging, as well as more effective non-invasive analysis for security, nuclear safety, or product inspection applications. Herein, the principles behind the rapid rises in performance of LHP and perovskite-inspired material detectors, and how their properties and performance link with critical applications in non-invasive diagnostics are discussed. The key strategies to engineer the performance of these materials, and the important challenges to overcome to commercialize these new technologies are also discussed.
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Affiliation(s)
| | - Thanh-Hai Le
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Wanyi Nie
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Robert L Z Hoye
- Inorganic Chemistry Laboratory, University of Oxford, Oxford, OX1 3QR, UK
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4
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Mendes HR, Silva JC, Marcondes M, Tomal A. Optimization of image quality and dose in adult and pediatric chest radiography via Monte Carlo simulation and experimental methods. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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5
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Ayesh AI, Salah B, Nawwas R, Almarri AS, Al‐Thani AN, Al‐Ahbabi AM, Al Haidous NA. Investigation of x‐ray response for flexible nanocomposite membranes of metal oxides and poly(vinyl alcohol). J Appl Polym Sci 2022. [DOI: 10.1002/app.51850] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Ahmad I. Ayesh
- Physics Program, Department of Math., Stat. and Physics, College of Arts and Sciences Qatar University Doha Qatar
| | - Belal Salah
- Physics Program, Department of Math., Stat. and Physics, College of Arts and Sciences Qatar University Doha Qatar
| | - Rama Nawwas
- Department of Computer Science & Engineering Qatar University Doha Qatar
| | - Asmaa S. Almarri
- Department of Computer Science & Engineering Qatar University Doha Qatar
| | - Aisha N. Al‐Thani
- Department of Computer Science & Engineering Qatar University Doha Qatar
| | | | - Noof A. Al Haidous
- Department of Computer Science & Engineering Qatar University Doha Qatar
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Kamburoğlu K, Samunahmetoğlu E, Eratam N, Sönmez G, Karahan S. Clinical comparison of intraoral CMOS and PSP detectors in terms of time efficiency, patient comfort, and subjective image quality. Imaging Sci Dent 2022; 52:93-101. [PMID: 35387105 PMCID: PMC8967495 DOI: 10.5624/isd.20210241] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 12/13/2021] [Accepted: 12/29/2021] [Indexed: 11/18/2022] Open
Affiliation(s)
- Kıvanç Kamburoğlu
- Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Ankara University, Ankara, Turkey
| | - Erçin Samunahmetoğlu
- Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Ankara University, Ankara, Turkey
| | - Nejlan Eratam
- Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Ankara University, Ankara, Turkey
| | - Gül Sönmez
- Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Adakent University, Mersin, Turkey
| | - Sevilay Karahan
- Department of Biostatistics, Faculty of Medicine, Hacettepe University, Ankara, Turkey
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Notohamiprodjo S, Roeper KM, Treitl KM, Hoberg B, Wanninger F, Verstreepen L, Mueck FG, Maxien D, Fischer F, Peschel O, Wirth S. Image quality is resilient against tube voltage variations in post-mortem skeletal radiography with a digital flat-panel detector. Sci Rep 2021; 11:7701. [PMID: 33833315 PMCID: PMC8032833 DOI: 10.1038/s41598-021-87294-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 03/24/2021] [Indexed: 11/09/2022] Open
Abstract
In recent phantom studies low-contrast detectability was shown to be independent from variations in tube voltage in digital radiography (DR) systems. To investigate the transferability to a clinical setting, the lower extremities of human cadavers were exposed at constant detector doses with different tube voltages in a certain range, as proposed in the phantom studies. Three radiologists independently graded different aspects of image quality (IQ) in a comparative analysis. The grades show no correlation between IQ and kV, which means that the readers were not able to recognize a significant IQ difference at different kV. Signal-to-noise and contrast-to-noise ratios showed no significant differences in IQ despite the kV-setting variations. These findings were observed from a limited kV range setting. Higher kV-settings resulted in lowest patient exposure at constant IQ. These results confirm the potential of DR-systems to contribute to standardization of examination protocols comparable to computed tomography. This may prevent the trend to overexpose. Further investigations in other body regions and other DR-systems are encouraged to determine transferability.
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Affiliation(s)
- S Notohamiprodjo
- Department of Nuclear Medicine, Klinikum Rechts Der Isar, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany.
| | - K M Roeper
- Department of Ophtalmology, Klinikum Rechts Der Isar, Technical University of Munich, Munich, Germany
| | - K M Treitl
- Department of Radiology, University Hospital of Munich, LMU Munich, Munich, Germany
| | - B Hoberg
- Agfa HealthCare Germany GmbH, Bonn, Germany
| | - F Wanninger
- Agfa-Gevaert HealthCare GmbH, Munich, Germany
| | | | - F G Mueck
- Department of Radiology, HELIOS Klinikum München West, Munich, Germany
| | - D Maxien
- Radiologie Zentrum München, Munich, Germany
| | - F Fischer
- Institute of Forensic Medicine, LMU Munich, Munich, Germany
| | - O Peschel
- Institute of Forensic Medicine, LMU Munich, Munich, Germany
| | - S Wirth
- Institute of Radiology, Schwarzwald-Baar Klinikum, Villingen-Schwenningen, Germany
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8
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Keil H, Luxenhofer M, Vetter SY, Beisemann N, Grützner PA, Franke J. Evaluation of image quality and assessability of a new flat‐panel 3D C‐arm compared to mobile and fixed computed tomography in posterior spinal fixation. Int J Med Robot 2020; 17:e2181. [DOI: 10.1002/rcs.2181] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 09/25/2020] [Accepted: 10/07/2020] [Indexed: 11/06/2022]
Affiliation(s)
- Holger Keil
- Department of Trauma and Orthopaedic Surgery Krankenhausstr Universitätsklinikum Erlangen Erlangen Germany
| | - Miriam Luxenhofer
- BG Trauma Center Ludwigshafen Department of Trauma and Orthopaedic Surgery Ludwigshafen Germany
| | - Sven Y. Vetter
- BG Trauma Center Ludwigshafen Department of Trauma and Orthopaedic Surgery Ludwigshafen Germany
| | - Nils Beisemann
- BG Trauma Center Ludwigshafen Department of Trauma and Orthopaedic Surgery Ludwigshafen Germany
| | - Paul A. Grützner
- BG Trauma Center Ludwigshafen Department of Trauma and Orthopaedic Surgery Ludwigshafen Germany
| | - Jochen Franke
- BG Trauma Center Ludwigshafen Department of Trauma and Orthopaedic Surgery Ludwigshafen Germany
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9
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Tsai H, Liu F, Shrestha S, Fernando K, Tretiak S, Scott B, Vo DT, Strzalka J, Nie W. A sensitive and robust thin-film x-ray detector using 2D layered perovskite diodes. SCIENCE ADVANCES 2020; 6:eaay0815. [PMID: 32300647 PMCID: PMC7148088 DOI: 10.1126/sciadv.aay0815] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 01/14/2020] [Indexed: 05/03/2023]
Abstract
Solid-state radiation detectors, using crystalline semiconductors to convert radiation photons to electrical charges, outperform other technologies with high detectivity and sensitivity. Here, we demonstrate a thin-film x-ray detector comprised with highly crystalline two-dimensional Ruddlesden-Popper phase layered perovskites fabricated in a fully depleted p-i-n architecture. It shows high diode resistivity of 1012 ohm·cm in reverse-bias regime leading to a high x-ray detecting sensitivity up to 0.276 C Gyair -1 cm-3. Such high signal is collected by the built-in potential underpinning operation of primary photocurrent device with robust operation. The detectors generate substantial x-ray photon-induced open-circuit voltages that offer an alternative detecting mechanism. Our findings suggest a new generation of x-ray detectors based on low-cost layered perovskite thin films for future x-ray imaging technologies.
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Affiliation(s)
- Hsinhan Tsai
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87544, USA
| | - Fangze Liu
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87544, USA
| | - Shreetu Shrestha
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87544, USA
| | - Kasun Fernando
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87544, USA
| | - Sergei Tretiak
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87544, USA
| | - Brian Scott
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87544, USA
| | - Duc Ta Vo
- Nuclear Engineering and Nonproliferation, Los Alamos National Laboratory, Los Alamos, NM 87544, USA
| | - Joseph Strzalka
- X-Ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Wanyi Nie
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87544, USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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10
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Matyagin YV, McRobbie DW. Muscle and bone dose in paediatric limb digital radiography: a Monte Carlo evaluation. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2019; 43:10.1007/s13246-019-00820-y. [PMID: 31748969 DOI: 10.1007/s13246-019-00820-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 11/11/2019] [Indexed: 11/24/2022]
Abstract
The proliferation of digital radiography (DR) has led to a re-evaluation of exposure parameters and image quality. Currently, there is a move towards reducing X-ray tube voltage (kVp) in paediatric exposures down to 40 kVp to achieve better images. However, the effect on patient dose of these modifications is uncertain. The main aims of this phantom study were to evaluate the effect of reducing the kVp in paediatric limb DR exposures on contrast-to-noise ratio (CNR) and patient dose. For this purpose, Monte Carlo simulations of radiographic exposures on a paediatric limb phantom were performed. The phantom included muscle tissue and bone segments of five different densities in the range of 1.12 to 1.48 g/cm3. The overall thickness of the phantom varied between 1 and 12 cm. Dependence of the CNR at constant limb phantom muscle and bone doses and dependence of the CNR per unit of muscle and bone dose at constant detector dose on radiographic exposure factors and limb thickness were calculated. X-ray tube current-time product (mAs) values required to achieve equal detector dose versus limb thickness for different kVp were calculated, as well as muscle and bone doses for the limb phantom of varying thickness. Present work has shown that reducing the kVp in paediatric radiography of the extremities can result in a significant increase in radiation dose, particularly for thicker limbs. Low kVp radiography requires justification for use on the extremities.
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Affiliation(s)
- Yuri V Matyagin
- South Australia Medical Imaging, Royal Adelaide Hospital, Port Road, Adelaide, SA, 5000, Australia.
| | - Donald W McRobbie
- South Australia Medical Imaging, Flinders Medical Centre, Flinders Drive, Bedford Park, SA, 5042, Australia
- School of Physical Sciences, University of Adelaide, Adelaide, SA, 5000, Australia
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11
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Blum A, Noël A, Regent D, Villani N, Gillet R, Gondim Teixeira P. Tomosynthesis in musculoskeletal pathology. Diagn Interv Imaging 2018; 99:423-441. [DOI: 10.1016/j.diii.2018.05.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 05/15/2018] [Indexed: 01/08/2023]
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Abstract
The invention of flat-panel detectors led to a revolution in medical imaging. The major benefits of this technology are a higher image quality and dose reduction. Flat-panel detectors have proved to be superior to standard C-arms (= C-arm with radiograph source and image intensifier). Cone-beam computed tomography (cone-beam CT) is a 3D data set, which can be acquired with a flat-panel detector. The cone-shaped beam is used for 3D data generation. For cone-beam CT acquisition, the flat-panel detector rotates around the patient lying on the operating table. Intra-operative cone-beam CT can be a very helpful tool in orthopaedic surgery. Immediate control of fracture reduction and implant positioning in high image quality can reduce the need for secondary revision surgery due to implant malposition. In recent years there has been a revival of standard fan beam CT technology in operating rooms. Fixed and mobile systems are available. Fixed systems are typically placed on a sliding gantry. Different mobile intra-operative CT scanners were recently introduced. Due to their mobility, they are not bound to a specific operating room. The use of standard intra-operative CT scanners results in high 3D image quality but, in comparison with a cone-beam CT scanner, fluoroscopy is not possible. The introduction of flat-panel detectors has led to improvements in intra-operative image quality combined with dose reduction. The possibility of high-quality 3D imaging in combination with navigation can assure optimal implant placement. Due to immediate control of the osteosynthesis, revision surgery at a later time can be prevented.
Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170055
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Booth NJ, Morley SJ, Ewers RS. Use of radiography in small animal practice in the UK and Republic of Ireland in 2013. Vet Rec 2018; 182:225. [DOI: 10.1136/vr.104670] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 12/21/2017] [Accepted: 01/11/2018] [Indexed: 01/26/2023]
Affiliation(s)
- Naomi J Booth
- School of Veterinary Medicine & Science, University of Nottingham; Nottingham UK
| | - Samuel J Morley
- School of Veterinary Medicine & Science, University of Nottingham; Nottingham UK
| | - Richard S Ewers
- School of Veterinary Medicine & Science, University of Nottingham; Nottingham UK
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Kawashima H, Ichikawa K, Nagasou D, Hattori M. X-ray dose reduction using additional copper filtration for abdominal digital radiography: Evaluation using signal difference-to-noise ratio. Phys Med 2017; 34:65-71. [DOI: 10.1016/j.ejmp.2017.01.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 12/24/2016] [Accepted: 01/19/2017] [Indexed: 10/20/2022] Open
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Kim TH, Ryu JH, Jeong CW, Jun HY, Heo DW, Lee SH, Oh YK, Lee MJ, Yoon KH. Reduced radiation dose and improved image quality using a mini mobile digital imaging system in a neonatal intensive care unit. Clin Imaging 2016; 42:165-171. [PMID: 28064140 DOI: 10.1016/j.clinimag.2016.12.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 11/24/2016] [Accepted: 12/02/2016] [Indexed: 11/19/2022]
Abstract
This study was aimed to assess the radiation dose and image quality of a mini-mobile digital imaging (mini-DI) system for neonatal chest radiography and compared to conventional digital radiography (DR). A total of 64 neonates were examined and anatomical landmarks were assessed. The entrance surface dose of mini DI and conventional DR was 26.64±0.15 μGy and 49.11±1.46 μGy, respectively (p<0.001). The mean SNR values for mini-DI and DR were 233.2±5.1 and 31.6±1.2, and 10% MTF values were 131 and 161μm. A newly developed mini-DI is capable of preserving the diagnostic information with dose reduction in neonates under intensive care.
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Affiliation(s)
- Tae-Hoon Kim
- Imaging Science Research Center, Wonkwang University School of Medicine, Iksan, Jeonbuk, South Korea
| | - Jong-Hyun Ryu
- Imaging Science Research Center, Wonkwang University School of Medicine, Iksan, Jeonbuk, South Korea
| | - Chang-Won Jeong
- Imaging Science Research Center, Wonkwang University School of Medicine, Iksan, Jeonbuk, South Korea
| | - Hong Young Jun
- Imaging Science Research Center, Wonkwang University School of Medicine, Iksan, Jeonbuk, South Korea
| | - Dong-Woon Heo
- Imaging Science Research Center, Wonkwang University School of Medicine, Iksan, Jeonbuk, South Korea
| | - Seung Hyun Lee
- Department of Pediatrics, Wonkwang University School of Medicine
| | - Yeon Kyun Oh
- Department of Pediatrics, Wonkwang University School of Medicine
| | - Mi-Jung Lee
- Department of Radiology, Yonsei University School of Medicine, Seoul, South Korea
| | - Kwon-Ha Yoon
- Imaging Science Research Center, Wonkwang University School of Medicine, Iksan, Jeonbuk, South Korea; Department of Radiology, Wonkwang University School of Medicine, Iksan, Jeonbuk, South Korea.
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16
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Development of a mini-mobile digital radiography system by using wireless smart devices. J Digit Imaging 2015; 27:443-8. [PMID: 24526518 DOI: 10.1007/s10278-013-9659-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
The current technologies that trend in digital radiology (DR) are toward systems using portable smart mobile as patient-centered care. We aimed to develop a mini-mobile DR system by using smart devices for wireless connection into medical information systems. We developed a mini-mobile DR system consisting of an X-ray source and a Complementary Metal-Oxide Semiconductor (CMOS) sensor based on a flat panel detector for small-field diagnostics in patients. It is used instead of the systems that are difficult to perform with a fixed traditional device. We also designed a method for embedded systems in the development of portable DR systems. The external interface used the fast and stable IEEE 802.11n wireless protocol, and we adapted the device for connections with Picture Archiving and Communication System (PACS) and smart devices. The smart device could display images on an external monitor other than the monitor in the DR system. The communication modules, main control board, and external interface supporting smart devices were implemented. Further, a smart viewer based on the external interface was developed to display image files on various smart devices. In addition, the advantage of operators is to reduce radiation dose when using remote smart devices. It is integrated with smart devices that can provide X-ray imaging services anywhere. With this technology, it can permit image observation on a smart device from a remote location by connecting to the external interface. We evaluated the response time of the mini-mobile DR system to compare to mobile PACS. The experimental results show that our system outperforms conventional mobile PACS in this regard.
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Seco J, Clasie B, Partridge M. Review on the characteristics of radiation detectors for dosimetry and imaging. Phys Med Biol 2014; 59:R303-47. [PMID: 25229250 DOI: 10.1088/0031-9155/59/20/r303] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The enormous advances in the understanding of human anatomy, physiology and pathology in recent decades have led to ever-improving methods of disease prevention, diagnosis and treatment. Many of these achievements have been enabled, at least in part, by advances in ionizing radiation detectors. Radiology has been transformed by the implementation of multi-slice CT and digital x-ray imaging systems, with silver halide films now largely obsolete for many applications. Nuclear medicine has benefited from more sensitive, faster and higher-resolution detectors delivering ever-higher SPECT and PET image quality. PET/MR systems have been enabled by the development of gamma ray detectors that can operate in high magnetic fields. These huge advances in imaging have enabled equally impressive steps forward in radiotherapy delivery accuracy, with 4DCT, PET and MRI routinely used in treatment planning and online image guidance provided by cone-beam CT. The challenge of ensuring safe, accurate and precise delivery of highly complex radiation fields has also both driven and benefited from advances in radiation detectors. Detector systems have been developed for the measurement of electron, intensity-modulated and modulated arc x-ray, proton and ion beams, and around brachytherapy sources based on a very wide range of technologies. The types of measurement performed are equally wide, encompassing commissioning and quality assurance, reference dosimetry, in vivo dosimetry and personal and environmental monitoring. In this article, we briefly introduce the general physical characteristics and properties that are commonly used to describe the behaviour and performance of both discrete and imaging detectors. The physical principles of operation of calorimeters; ionization and charge detectors; semiconductor, luminescent, scintillating and chemical detectors; and radiochromic and radiographic films are then reviewed and their principle applications discussed. Finally, a general discussion of the application of detectors for x-ray nuclear medicine and ion beam imaging and dosimetry is presented.
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Affiliation(s)
- Joao Seco
- Department of Radiation Oncology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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Jones AK, Balter S, Rauch P, Wagner LK. Medical imaging using ionizing radiation: optimization of dose and image quality in fluoroscopy. Med Phys 2014; 41:014301. [PMID: 24387534 DOI: 10.1118/1.4835495] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The 2012 Summer School of the American Association of Physicists in Medicine (AAPM) focused on optimization of the use of ionizing radiation in medical imaging. Day 2 of the Summer School was devoted to fluoroscopy and interventional radiology and featured seven lectures. These lectures have been distilled into a single review paper covering equipment specification and siting, equipment acceptance testing and quality control, fluoroscope configuration, radiation effects, dose estimation and measurement, and principles of flat panel computed tomography. This review focuses on modern fluoroscopic equipment and is comprised in large part of information not found in textbooks on the subject. While this review does discuss technical aspects of modern fluoroscopic equipment, it focuses mainly on the clinical use and support of such equipment, from initial installation through estimation of patient dose and management of radiation effects. This review will be of interest to those learning about fluoroscopy, to those wishing to update their knowledge of modern fluoroscopic equipment, to those wishing to deepen their knowledge of particular topics, such as flat panel computed tomography, and to those who support fluoroscopic equipment in the clinic.
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Affiliation(s)
- A Kyle Jones
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Stephen Balter
- Departments of Radiology and Medicine, Columbia University, New York, New York 10032
| | - Phillip Rauch
- Retired-Henry Ford Health System, Detroit, Michigan 48202
| | - Louis K Wagner
- Department of Diagnostic and Interventional Imaging, The University of Texas Medical School at Houston, Houston, Texas 77030
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Pellerin O, Lin M, Bhagat N, Shao W, Geschwind JF. Can C-arm cone-beam CT detect a micro-embolic effect after TheraSphere radioembolization of neuroendocrine and carcinoid liver metastasis? Cancer Biother Radiopharm 2014; 28:459-65. [PMID: 23484809 DOI: 10.1089/cbr.2012.1390] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
RATIONAL AND OBJECTIVE Radioembolization with yttrium-90 microspheres is a therapy that is used for hepatic tumors. 20-30 μm microspheres loaded with Y90 are supposedly occluding tumor vessels at the capillary level. Then, these spheres deliver high-dose radiation to the tumor. However, this theoretical embolic effect has never been appreciated in imaging. Dual-Phase cone-beam computed tomography (DPCBCT) is a multi-phasic intra-procedural scan that uses only one contrast media injection to visualize early (feeding vessel) and delayed (capillary level) tumor enhancement. The purpose of this study was to determine whether there is a micro-embolic effect induced by TheraSpheres® (MDS Nordion, Ottawa, Ontario, Canada) at the capillary level by using DPCBCT imaging. MATERIALS AND METHODS 14 patients with 72 carcinoid or neuroendocrine tumors were treated with radioembolization, and all underwent DPCBCT (Allura Xper, Philips Healthcare) imaging before and immediately after radioembolization with TheraSpheres®. Tumor enhancement was measured in each phase by drawing a region of interest within the tumors. RESULTS 72 tumors were evaluated: average tumor density in the early arterial phase was 241 and 230 Hounsfield units (HU) (p<0.001) before and after radioembolization, respectively; the average density in the delayed arterial phase was 226 and 161 HU (p<0.001) before and after radioembolization, respectively. Average difference in tumor attenuation before and after radioembolization in early arterial and delayed phase was 11 HU and 64 HU (p<0.001), respectively. CONCLUSION The significant decrease in tumor enhancement in the DPCBCT delayed phase after TheraSpheres® injection indicates that there is an appreciable microembolic effect at the tumor capillary bed level.
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Affiliation(s)
- Olivier Pellerin
- Division of Vascular and Interventional Radiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Hospital, Baltimore, Maryland 21287, USA
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Acciavatti RJ, Maidment ADA. Oblique reconstructions in tomosynthesis. I. Linear systems theory. Med Phys 2013; 40:111911. [PMID: 24320444 DOI: 10.1118/1.4819941] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
PURPOSE By convention, slices in a tomosynthesis reconstruction are created on planes parallel to the detector. It has not yet been demonstrated that slices can be generated along oblique directions through the same volume, analogous to multiplanar reconstructions in computed tomography (CT). The purpose of this work is to give a proof-of-principle justification for oblique reconstructions in tomosynthesis, which acquires projection images over a smaller angular range than CT. METHODS To investigate the visibility of individual frequencies in an oblique reconstruction, a theoretical framework is developed in which the reconstruction of a sinusoidal input is calculated. The test frequency is pitched at an angle in a 2D parallel-beam acquisition geometry. Reconstructions are evaluated along the pitch of the object. The modulation transfer function (MTF) is calculated from the relative signal at various test frequencies. The MTF determines whether modulation is within detectable limits in oblique reconstructions. In the previous linear systems (LS) model [B. Zhao and W. Zhao, "Three-dimensional linear system analysis for breast tomosynthesis," Med. Phys. 35(12), 5219-5232 (2008)], the MTF was calculated only in reconstructed slices parallel to the detector. This paper generalizes the MTF calculation to reconstructed slices at all possible pitches. Unlike the previous LS model, this paper also analyzes the effect of object thickness on the MTF. A second test object that is considered is a rod whose long axis is pitched similar to the sinusoidal input. The rod is used to assess whether the length of an object can be correctly estimated in oblique reconstructions. RESULTS To simulate the conventional display of the reconstruction, slices are first created along a 0° pitch. This direction is perpendicular to the rays of the central projection. The authors show that the input frequency of a pitched sinusoidal object cannot be determined using these slices. By changing the pitch of the slice to match the object, it is shown that the input frequency is properly resolved. To prove that modulation is preserved in pitched slices, the MTF is also calculated. Modulation is within detectable limits over a broad range of pitches if the object is thin, but is detectable over a narrower range of pitches if the object is thick. Turning next to the second test object, it is shown that the length of a pitched rod can be correctly determined in oblique reconstructions. Concordant with the behavior of the MTF, the length estimate is accurate over a broad range of pitches if the object is thin, but is correct over a narrower range of pitches if the object is thick. CONCLUSIONS This work justifies the feasibility of oblique reconstructions in tomosynthesis. It is demonstrated that pitched test objects are most easily visualized with oblique reconstructions instead of conventional reconstructions. In order to achieve high image quality over a broad range of pitches, the object must be thin. By analyzing the effect of reconstruction pitch and object thickness on image quality, this paper generalizes the previous LS model for tomosynthesis.
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Affiliation(s)
- Raymond J Acciavatti
- Department of Radiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104-4206
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Samei E, Murphy S, Christianson O. DQE of wireless digital detectors: Comparative performance with differing filtration schemes. Med Phys 2013; 40:081910. [DOI: 10.1118/1.4813298] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Alsleem H, Davidson R. Factors Affecting Contrast-Detail Performance in Computed Tomography: A Review. J Med Imaging Radiat Sci 2013; 44:62-70. [DOI: 10.1016/j.jmir.2012.12.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 12/03/2012] [Accepted: 12/11/2012] [Indexed: 10/27/2022]
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Detectores radiográficos digitales inalámbricos en una sala de radiología de urgencias. Una solución eficaz. RADIOLOGIA 2013; 55:239-46. [DOI: 10.1016/j.rx.2011.08.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2011] [Revised: 08/02/2011] [Accepted: 08/02/2011] [Indexed: 11/21/2022]
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Garrido Blázquez M, Agulla Otero M, Rodríguez Recio F, Torres Cabrera R, Hernando González I. Wireless digital radiography detectors in the emergency area: An efficacious solution. RADIOLOGIA 2013. [DOI: 10.1016/j.rxeng.2011.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Acciavatti RJ, Maidment ADA. Observation of super-resolution in digital breast tomosynthesis. Med Phys 2013; 39:7518-39. [PMID: 23231301 DOI: 10.1118/1.4757583] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Digital breast tomosynthesis (DBT) is a 3D x-ray imaging modality in which tomographic sections of the breast are generated from a limited range of tube angles. Because oblique x-ray incidence shifts the image of an object in subpixel detector element increments with each increasing projection angle, it is demonstrated that DBT is capable of super-resolution (i.e., subpixel resolution). METHODS By convention, DBT reconstructions are performed on planes parallel to the breast support at various depths of the breast volume. In order for resolution in each reconstructed slice to be comparable to the detector, the pixel size should match that of the detector elements; hence, the highest frequency that can be resolved in the plane of reconstruction is the alias frequency of the detector. This study considers reconstruction grids with much smaller pixelation to visualize higher frequencies. For analytical proof of super-resolution, a theoretical framework is developed in which the reconstruction of a high frequency sinusoidal input is calculated using both simple backprojection (SBP) and filtered backprojection. To study the frequency spectrum of the reconstruction, its Fourier transform is also determined. The experimental feasibility of super-resolution was investigated by acquiring images of a bar pattern phantom with frequencies higher than the detector alias frequency. RESULTS Using analytical modeling, it is shown that the central projection cannot resolve frequencies exceeding the detector alias frequency. The Fourier transform of the central projection is maximized at a lower frequency than the input as evidence of aliasing. By contrast, SBP reconstruction can resolve the input, and its Fourier transform is correctly maximized at the input frequency. Incorporating filters into the reconstruction smoothens pixelation artifacts in the spatial domain and reduces spectral leakage in the Fourier domain. It is also demonstrated that the existence of super-resolution is dependent on position in the reconstruction and on the directionality of the input frequency. Consistent with the analytical results, experimental reconstructions of bar patterns showed visibility of frequencies greater than the detector alias frequency. Super-resolution was present at positions predicted from analytical modeling. CONCLUSIONS This work demonstrates the existence of super-resolution in DBT. Super-resolution has the potential to impact the visualization of fine structural details in the breast, such as microcalcifications and other subtle signs of cancer.
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A feasibility study on reduction of the entrance-surface dose to neonates by use of a new digital mobile X-ray system. Radiol Phys Technol 2012; 6:157-61. [DOI: 10.1007/s12194-012-0182-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 10/01/2012] [Accepted: 10/08/2012] [Indexed: 11/25/2022]
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Acciavatti RJ, Maidment ADA. Optimization of phosphor-based detector design for oblique x-ray incidence in digital breast tomosynthesis. Med Phys 2012; 38:6188. [PMID: 22047384 DOI: 10.1118/1.3639999] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
PURPOSE In digital breast tomosynthesis (DBT), a volumetric reconstruction of the breast is generated from a limited range of x-ray projections. One trade-off of DBT is resolution loss in the projections due to non-normal (i.e., oblique) x-ray incidence. Although degradation in image quality due to oblique incidence has been studied using empirical data and Monte Carlo simulations, a theoretical treatment has been lacking. The purpose of this work is to extend Swank's calculations of the transfer functions of turbid granular phosphors to oblique incidence. The model is ultimately used as a tool for optimizing the design of DBT detectors. METHODS A quantum-limited system and 20 keV x-rays are considered. Under these assumptions, the modulation transfer function (MTF) and noise power spectra (NPS) are derived using the diffusion approximation to the Boltzmann equation to model optical scatter within the phosphor. This approach is applicable to a nonstructured scintillator such as gadolinium oxysulfide doped with terbium (Gd(2)O(2)S:Tb), which is commonly used in breast imaging and which can reasonably approximate other detector materials. The detective quantum efficiency (DQE) is then determined from the Nishikawa formulation, where it is written as the product of the x-ray quantum detection efficiency, the Swank factor, and the Lubberts fraction. Transfer functions are calculated for both front- and back-screen configurations, which differ by positioning the photocathode at the exit or entrance point of the x-ray beam, respectively. RESULTS In the front-screen configuration, MTF and DQE are found to have considerable angular dependence, while NPS is shown to vary minimally with projection angle. As expected, the high frequency MTF and DQE are degraded substantially at large angles. By contrast, all transfer functions for the back-screen configuration have the advantage of significantly less angular dependence. Using these models, we investigated the possibility for optimizing the design of DBT detectors. As an example optimization strategy, the phosphor thickness which maximizes the DQE at a fixed frequency is analyzed. This work demonstrates that the optimal phosphor thickness for the front-screen is angularly dependent, shifting to lower thickness at higher angles. Conversely, the back-screen is not optimized by a single thickness but instead attains reasonably high DQE values over a large range of thicknesses. Although the back-screen configuration is not suited for current detectors using a glass substrate, it may prove to be preferred in future detectors using newly proposed plastic thin-film transistor (TFT) substrates. CONCLUSIONS Using the diffusion approximation to the Boltzmann equation to model the spread of light in a scintillator, this paper develops an analytical model of MTF, NPS, and DQE for a phosphor irradiated obliquely. The model is set apart from other studies on oblique incidence in being derived from first principles. This work has applications in the optimization of DBT detector design.
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Affiliation(s)
- Raymond J Acciavatti
- Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA
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Ludewig E, Pees M, Morgan JP. Clinical Technique: Digital Radiography in Exotic Pets—Important Practical Differences Compared with Traditional Radiography. J Exot Pet Med 2012. [DOI: 10.1053/j.jepm.2011.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Novel, portable, cassette-sized, and wireless flat-panel digital radiography system: initial workflow results versus computed radiography. AJR Am J Roentgenol 2011; 196:1368-71. [PMID: 21606301 DOI: 10.2214/ajr.10.5867] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
OBJECTIVE The purpose of this article is to compare workflow efficiency between a conventional computed radiography (CR) system and a novel, portable, cassette-sized, and wireless flat-panel digital radiography (DR) system. MATERIALS AND METHODS Observational time-motion analyses were performed at one site at which CR and the new portable DR system are used concurrently. The workflow steps of both systems were identified and categorized to facilitate comparison. The times required for examination preparation, patient positioning, exposure, postacquisition processing, and the examination as a whole were recorded by a neutral observer. Timing differences between the CR and portable DR systems were compared, and all data were analyzed using commercially available statistical software. Nine general radiographic examination types were selected, with approximately 50 patients per examination type. RESULTS A total of 941 examinations (CR, n = 474; portable DR, n = 467) were timed in this study. Total examination time differences between CR and portable DR system (mean, 26.44 seconds; median 26.99 seconds) were found to be statistically significant (p < 0.001), with DR proving faster than CR. The single largest contributor to the time difference between CR and portable DR was postacquisition processing (mean, 26.58 seconds; median, 25.91 seconds), which was a composite of multiple individual steps, including cassette transport (CR only, mean, 13.22 seconds; median, 12.74 seconds), cassette readout (mean, 10.15 seconds; median, 10.4 seconds), and postprocessing (mean, 3.21 seconds; median, 3.11 seconds). CONCLUSION Overall radiographer time was significantly shorter when performing examination-related tasks with the novel, portable DR system than when performing comparable tasks with the CR system, a difference that appears to result largely from technology configuration.
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Acciavatti RJ, Maidment ADA. A comparative analysis of OTF, NPS, and DQE in energy integrating and photon counting digital x-ray detectors. Med Phys 2011; 37:6480-95. [PMID: 21302803 DOI: 10.1118/1.3505014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
PURPOSE One of the benefits of photon counting (PC) detectors over energy integrating (EI) detectors is the absence of many additive noise sources, such as electronic noise and secondary quantum noise. The purpose of this work is to demonstrate that thresholding voltage gains to detect individual x rays actually generates an unexpected source of white noise in photon counters. METHODS To distinguish the two detector types, their point spread function (PSF) is interpreted differently. The PSF of the energy integrating detector is treated as a weighting function for counting x rays, while the PSF of the photon counting detector is interpreted as a probability. Although this model ignores some subtleties of real imaging systems, such as scatter and the energy-dependent amplification of secondary quanta in indirect-converting detectors, it is useful for demonstrating fundamental differences between the two detector types. From first principles, the optical transfer function (OTF) is calculated as the continuous Fourier transform of the PSF, the noise power spectra (NPS) is determined by the discrete space Fourier transform (DSFT) of the autocovariance of signal intensity, and the detective quantum efficiency (DQE) is found from combined knowledge of the OTF and NPS. To illustrate the calculation of the transfer functions, the PSF is modeled as the convolution of a Gaussian with the product of rect functions. The Gaussian reflects the blurring of the x-ray converter, while the rect functions model the sampling of the detector. RESULTS The transfer functions are first calculated assuming outside noise sources such as electronic noise and secondary quantum noise are negligible. It is demonstrated that while OTF is the same for two detector types possessing an equivalent PSF, a frequency-independent (i.e., "white") difference in their NPS exists such that NPS(PC) > or = NPS(EI) and hence DQE(PC) < or = DQE(EI). The necessary and sufficient condition for equality is that the PSF is a binary function given as zero or unity everywhere. In analyzing the model detector with Gaussian blurring, the difference in NPS and DQE between the two detector types is found to increase with the blurring of the x-ray converter. Ultimately, the expression for the additive white noise of the photon counter is compared against the expression for electronic noise and secondary quantum noise in an energy integrator. Thus, a method is provided to determine the average secondary quanta that the energy integrator must produce for each x ray to have superior DQE to a photon counter with the same PSF. CONCLUSIONS This article develops analytical models of OTF, NPS, and DQE for energy integrating and photon counting digital x-ray detectors. While many subtleties of real imaging systems have not been modeled, this work is illustrative in demonstrating an additive source of white noise in photon counting detectors which has not yet been described in the literature. One benefit of this analysis is a framework for determining the average secondary quanta that an energy integrating detector must produce for each x ray to have superior DQE to competing photon counting technology.
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Affiliation(s)
- Raymond J Acciavatti
- Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Katsoni E, Tsalafoutas IA, Gritzalis P, Stefanou E, Georgiou E, Yakoumakis E. Exploring the useful exposure range limits of three intraoral image receptors for various tube potential, tube current and exposure time settings. Health (London) 2011. [DOI: 10.4236/health.2011.35051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Comparaison de l’irradiation en scanner et tomosynthèse du poignet. ACTA ACUST UNITED AC 2011; 92:32-9. [DOI: 10.1016/j.jradio.2010.11.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 10/01/2010] [Accepted: 11/02/2010] [Indexed: 11/19/2022]
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Katsoni E, Tsalafoutas IA, Gritzalis P, Stefanou E, Georgiou E, Yakoumakis E. Performance comparison between three intraoral image receptors of different technology at a variety of tube potential, tube current and exposure time settings using a stepwedge phantom. Health (London) 2011. [DOI: 10.4236/health.2011.31011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Sakae T, Hayakawa Y, Takahashi Y, Kuwada T, Nakao K, Nogami K, Inagaki M, Tanaka T, Sato I, Hirayama K, Sekiya K, Kaneda T, Suemitsu M, Okada H, Yamamoto H, Hata S, Akimoto Y, Fukumoto M, Makimura M. A Preliminary Study on Low-dose X-ray Imaging Using Parametric X-ray. J HARD TISSUE BIOL 2011. [DOI: 10.2485/jhtb.20.31] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Freed M, Miller S, Tang K, Badano A. Experimental validation of Monte Carlo (MANTIS) simulated x-ray response of columnar CsI scintillator screens. Med Phys 2010; 36:4944-56. [PMID: 19994503 DOI: 10.1118/1.3233683] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
PURPOSE MANTIS is a Monte Carlo code developed for the detailed simulation of columnar CsI scintillator screens in x-ray imaging systems. Validation of this code is needed to provide a reliable and valuable tool for system optimization and accurate reconstructions for a variety of x-ray applications. Whereas previous validation efforts have focused on matching of summary statistics, in this work the authors examine the complete point response function (PRF) of the detector system in addition to relative light output values. METHODS Relative light output values and high-resolution PRFs have been experimentally measured with a custom setup. A corresponding set of simulated light output values and PRFs have also been produced, where detailed knowledge of the experimental setup and CsI:Tl screen structures are accounted for in the simulations. Four different screens were investigated with different thicknesses, column tilt angles, and substrate types. A quantitative comparison between the experimental and simulated PRFs was performed for four different incidence angles (0 degrees, 15 degrees, 30 degrees, and 45 degrees) and two different x-ray spectra (40 and 70 kVp). The figure of merit (FOM) used measures the normalized differences between the simulated and experimental data averaged over a region of interest. RESULTS Experimental relative light output values ranged from 1.456 to 1.650 and were in approximate agreement for aluminum substrates, but poor agreement for graphite substrates. The FOMs for all screen types, incidence angles, and energies ranged from 0.1929 to 0.4775. To put these FOMs in context, the same FOM was computed for 2D symmetric Gaussians fit to the same experimental data. These FOMs ranged from 0.2068 to 0.8029. Our analysis demonstrates that MANTIS reproduces experimental PRFs with higher accuracy than a symmetric 2D Gaussian fit to the experimental data in the majority of cases. Examination of the spatial distribution of differences between the PRFs shows that the main reason for errors between MANTIS and the experimental data is that MANTIS-generated PRFs are sharper than the experimental PRFs. CONCLUSIONS The experimental validation of MANTIS performed in this study demonstrates that MANTIS is able to reliably predict experimental PRFs, especially for thinner screens, and can reproduce the highly asymmetric shape seen in the experimental data. As a result, optimizations and reconstructions carried out using MANTIS should yield results indicative of actual detector performance. Better characterization of screen properties is necessary to reconcile the simulated light output values with experimental data.
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Affiliation(s)
- Melanie Freed
- CDRH/NIBIB Laboratory for the Assessment of Medical Imaging Systems, Division of Imaging and Applied Mathematics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993-0002, USA.
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Miracle AC, Mukherji SK. Conebeam CT of the head and neck, part 1: physical principles. AJNR Am J Neuroradiol 2009; 30:1088-95. [PMID: 19439484 DOI: 10.3174/ajnr.a1653] [Citation(s) in RCA: 199] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Conebeam x-ray CT (CBCT) is a developing imaging technique designed to provide relatively low-dose high-spatial-resolution visualization of high-contrast structures in the head and neck and other anatomic areas. This first installment in a 2-part review will address the physical principles underlying CBCT imaging as it is used in dedicated head and neck scanners. Concepts related to CBCT acquisition geometry, flat panel detection, and image quality will be explored in detail. Particular emphasis will be placed on technical limitations to low-contrast detectability and radiation dose. Proposed methods of x-ray scatter reduction will also be discussed.
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Affiliation(s)
- A C Miracle
- Department of Radiology, University of Michigan Health System, University Hospital, Ann Arbor, MI 48109-5030, USA.
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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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