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Ahmed AMM, Buschmann M, Breyer L, Kuntner C, Homolka P. Tailoring the Mass Density of 3D Printing Materials for Accurate X-ray Imaging Simulation by Controlled Underfilling for Radiographic Phantoms. Polymers (Basel) 2024; 16:1116. [PMID: 38675035 PMCID: PMC11053449 DOI: 10.3390/polym16081116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 03/26/2024] [Accepted: 04/11/2024] [Indexed: 04/28/2024] Open
Abstract
Additive manufacturing and 3D printing allow for the design and rapid production of radiographic phantoms for X-ray imaging, including CT. These are used for numerous purposes, such as patient simulation, optimization of imaging procedures and dose levels, system evaluation and quality assurance. However, standard 3D printing polymers do not mimic X-ray attenuation properties of tissues like soft, adipose, lung or bone tissue, and standard materials like liquid water. The mass density of printing polymers-especially important in CT-is often inappropriate, i.e., mostly too high. Different methods can be applied to reduce mass density. This work examines reducing density by controlled underfilling either realized by using 3D printing materials expanded through foaming during heating in the printing process, or reducing polymer flow to introduce microscopic air-filled voids. The achievable density reduction depends on the base polymer used. When using foaming materials, density is controlled by the extrusion temperature, and ranges from 33 to 47% of the base polymer used, corresponding to a range of -650 to -394 HU in CT with 120 kV. Standard filaments (Nylon, modified PLA and modified ABS) allowed density reductions by 20 to 25%, covering HU values in CT from -260 to 77 (Nylon), -230 to -20 (ABS) and -81 to 143 (PLA). A standard chalk-filled PLA filament allowed reproduction of bone tissue in a wide range of bone mineral content resulting in CT numbers from 57 to 460 HU. Controlled underfilling allowed the production of radiographic phantom materials with continuously adjustable attenuation in a limited but appropriate range, allowing for the reproduction of X-ray attenuation properties of water, adipose, soft, lung, and bone tissue in an accurate, predictable and reproducible manner.
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Affiliation(s)
| | - Martin Buschmann
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, and University Hospital Vienna, 1090 Vienna, Austria;
| | - Lara Breyer
- Department of Biomedical Imaging and Image-Guided Therapy, Medical Imaging Cluster (MIC), Medical University of Vienna, 1090 Vienna, Austria; (L.B.); (C.K.)
| | - Claudia Kuntner
- Department of Biomedical Imaging and Image-Guided Therapy, Medical Imaging Cluster (MIC), Medical University of Vienna, 1090 Vienna, Austria; (L.B.); (C.K.)
| | - Peter Homolka
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, 1090 Vienna, Austria
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Marshall NW, Vandenbroucke D, Cockmartin L, Wanninger F, Smet M, Feng Y, Ni Y, Bosmans H. Seven general radiography x-ray detectors with pixel sizes ranging from 175 to 76 μm: technical evaluation with the focus on orthopaedic imaging. Phys Med Biol 2023; 68:195007. [PMID: 37659394 DOI: 10.1088/1361-6560/acf642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 09/01/2023] [Indexed: 09/04/2023]
Abstract
Aim. Flat panel detectors with small pixel sizes general can potentially improve imaging performance in radiography applications requiring fine detail resolution. This study evaluated the imaging performance of seven detectors, covering a wide range of pixel sizes, in the frame of orthopaedic applications.Material and methods. Pixel sizes ranged from 175 (detector A175) to 76μm (detector G76). Modulation transfer function (MTF) and detective quantum efficiency (DQE) were measured using International Electrotechnical Commission (IEC) RQA3 beam quality. Threshold contrast (CT) and a detectability index (d') were measured at three air kerma/image levels. Rabbit shoulder images acquired at 60 kV, over five air kerma levels, were evaluated in a visual grading study for anatomical sharpness, image noise and overall diagnostic image quality by four radiologists. The detectors were compared to detector E124.Results. The 10% point of the MTF ranged from 3.21 to 4.80 mm-1, in going from detector A175to detector G76. DQE(0.5 mm-1) measured at 2.38μGy/image was 0.50 ± 0.05 for six detectors, but was higher for F100at 0.62. High frequency DQE was superior for the smaller pixel detectors, howeverCTfor 0.25 mm discs correlated best with DQE(0.5 mm-1). Correlation betweenCTand the detectability model was good (R2= 0.964).CTfor 0.25 mm diameter discs was significantly higher for D150and F100compared to E124. The visual grading data revealed higher image quality ratings for detectors D125and F100compared to E124. An increase in air kerma was associated with improved perceived sharpness and overall quality score, independent of detector. Detectors B150, D125, F100and G76, performed well in specific tests, however only F100consistently outperformed the reference detector.Conclusion. Pixel size alone was not a reliable predictor of small detail detectability or even perceived sharpness in a visual grading analysis study.
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Affiliation(s)
- N W Marshall
- UZ Gasthuisberg, Department of Radiology, Herestraat 49, B-3000 Leuven, Belgium
- Medical Imaging Research Center, Medical Physics and Quality Assessment, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
- Agfa N.V., Septestraat 27, B-2640 Mortsel, Belgium
| | | | - L Cockmartin
- UZ Gasthuisberg, Department of Radiology, Herestraat 49, B-3000 Leuven, Belgium
| | - F Wanninger
- Agfa-Gevaert HealthCare GmbH, München, Germany
| | - M Smet
- UZ Gasthuisberg, Department of Radiology, Herestraat 49, B-3000 Leuven, Belgium
| | - Y Feng
- Theragnostic Laboratory, Biomedical Group, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
| | - Y Ni
- Theragnostic Laboratory, Biomedical Group, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
| | - H Bosmans
- UZ Gasthuisberg, Department of Radiology, Herestraat 49, B-3000 Leuven, Belgium
- Medical Imaging Research Center, Medical Physics and Quality Assessment, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
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Relationship between the visual evaluation of pathology visibility and the physical measure of low contrast detail detectability in neonatal chest radiography. Radiography (Lond) 2022; 28:1116-1121. [PMID: 36099681 DOI: 10.1016/j.radi.2022.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/11/2022] [Accepted: 08/16/2022] [Indexed: 11/22/2022]
Abstract
INTRODUCTION The detectability of low contrast detail (LCD) is a method used to assess image quality (IQ) in neonatal radiography; however, there is a lack of data on the relationship between LCD detectability and visual IQ. The study aims at investigating the relationship between the LCD detectability and visual IQ and pathology visibility (PV). METHODS Several acquisition parameters were employed to obtain a group of images from a neonatal Gammex chest phantom. Three observers applied relative visual grading analysis (VGA) for assessing the IQ and PV. A simulated pneumothorax visibility (PNV) and simulated hyaline membrane disease visibility (HMV) represented PV. Next, a CDRAD 2.0 phantom was radiographed utilising the same acquisition protocols, and several paired images were obtained. With the use of CDRAD analyser software, the detectability of LCD was assessed and expressed by an image quality figure inverse (IQFiinv) metric. The correlation between the IQFinv and each of IQ, PNV and HMV was examined. RESULTS The physical measure (IQFinv) and the visual assessment of IQ were shown to be strongly correlated (r = 0.95; p < 0.001). Using Pearson's correlation, the IQFinv, PNV, and HMV were found to be strongly correlated (r = 0.94; p < 0.001) and (r = 0.92; p < 0.001), correspondingly. CONCLUSION Results of the study show that physical measures of LCD detectability utilising the CDRAD 2.0 phantom is strongly corelated with visual IQ and PV (PNV and HMV) and can be used to evaluate IQ when undertaking neonatal chest radiography (CXR). IMPLICATIONS FOR PRACTICE This study establishes the feasibility of utilising the physical measure (IQFinv) and the CDRAD 2.0 phantom in routine quality assurance and neonatal CXR optimisation studies.
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Ma X, Buschmann M, Unger E, Homolka P. Classification of X-Ray Attenuation Properties of Additive Manufacturing and 3D Printing Materials Using Computed Tomography From 70 to 140 kVp. Front Bioeng Biotechnol 2021; 9:763960. [PMID: 34912790 PMCID: PMC8666890 DOI: 10.3389/fbioe.2021.763960] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 10/25/2021] [Indexed: 11/16/2022] Open
Abstract
Additive manufacturing and 3D printing is particularly useful in the production of phantoms for medical imaging applications including determination and optimization of (diagnostic) image quality and dosimetry. Additive manufacturing allows the leap from simple slab and stylized to (pseudo)-anthropomorphic phantoms. This necessitates the use of materials with x-ray attenuation as close as possible to that of the tissues or organs mimicked. X-ray attenuation properties including their energy dependence were determined for 35 printing materials comprising photocured resins and thermoplastic polymers. Prior to measuring x-ray attenuation in CT from 70 to 140 kVp, printing parameters were thoroughly optimized to ensure maximum density avoiding too low attenuation due to microscopic or macroscopic voids. These optimized parameters are made available. CT scanning was performed in a water filled phantom to guarantee defined scan conditions and accurate HU value determination. The spectrum of HU values covered by polymers printed using fused deposition modeling reached from −258 to +1,063 at 120 kVp (−197 to +1,804 at 70 kVp, to −266 to +985 at 140 kVp, respectively). Photocured resins covered 43 to 175 HU at 120 kVp (16–156 at 70, and 57–178 at 140 kVp). At 120 kVp, ASA mimics water almost perfectly (+2 HU). HIPS (−40 HU) is found close to adipose tissue. In all photocurable resins, and 17 printing filaments HU values decreased with increasing beam hardness contrary to soft tissues except adipose tissue making it difficult to mimic water or average soft tissue in phantoms correctly over a range of energies with one single printing material. Filled filaments provided both, the HU range, and an appropriate energy dependence mimicking bone tissues. A filled material with almost constant HU values was identified potentially allowing mimicking soft tissues by reducing density using controlled under-filling. The measurements performed in this study can be used to design phantoms with a wide range of x-ray contrasts, and energy dependence of these contrasts by combining appropriate materials. Data provided on the energy dependence can also be used to correct contrast or contrast to noise ratios from phantom measurements to real tissue contrasts or CNRs.
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Affiliation(s)
- Xiangjie Ma
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Martin Buschmann
- Division of Medical Radiation Physics, Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Ewald Unger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Peter Homolka
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
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Xu H, Huang K, Liu B, Cai J, Zheng H, Zheng H, Yang Q, Yao C. Influence of the use of various imaging units and projections on the radiation dose received by children during chest digital radiography. PLoS One 2021; 16:e0255749. [PMID: 34352022 PMCID: PMC8341633 DOI: 10.1371/journal.pone.0255749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/22/2021] [Indexed: 11/18/2022] Open
Abstract
Objective To investigate the impact of the use of different imaging units and projections on radiation dose and image quality during chest digital radiography (DR) in 3- and 4-year-old children. Methods Two hundred forty 3- and 4-year-old participants requiring chest DR were included; they were divided into three groups: supine anterior-posterior projection (APP), standing APP and standing posterior-anterior projection (PAP). Each group included 40 participants who were evaluated using the same imaging unit. The dose area product (DAP) and the entrance surface dose (ESD) were recorded after each exposure. The visual grading analysis score (VGAS) was used to evaluate image quality, and the longitudinal distance (LD) from the apex of the right lung to the apex of the right diaphragm was used to evaluate the inspiration extent. Results DAP and ESD were significantly lower in the standing PAP and APP groups than in the supine APP group (P<0.05), but LD was significantly higher in the standing PAP and APP groups than in the supine APP group (P<0.05). Additionally, the pulmonary field area was significantly higher for the standing PAP group than for the standing and supine APP groups (P<0.05). The correlations between ESD, DAP, and VGAS were positive (P<0.001), showing that larger ESD and DAP correspond to higher VGAS. The correlations between ESD, DAP, and body mass index (BMI) were also positive (P<0.05), indicating that higher BMI corresponds to larger ESD and DAP. Finally, no differences in DAP, ESD, VGAS, LD, pulmonary field area, or BMI were noted between males and females (P>0.05). Conclusion The radiation dose to superficial organs may be lower with standing PAP than with standing APP during chest DR. Standing PAP should be selected for chest DR in 3- and 4-year-old children, as it may decrease the required radiation dose.
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Affiliation(s)
- Hongrong Xu
- Department of Radiology, Children’s Hospital of Chongqing Medical University, Chongqing, China
- Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing, China
- National Clinical Research Center for Child Health and Disorders, Chongqing, China
- Chongqing Key Laboratory of Pediatrics, Chongqing, China
| | - Kaiping Huang
- Department of Radiology, Children’s Hospital of Chongqing Medical University, Chongqing, China
- Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing, China
- National Clinical Research Center for Child Health and Disorders, Chongqing, China
- Chongqing Key Laboratory of Pediatrics, Chongqing, China
| | - Bo Liu
- Department of Radiology, Children’s Hospital of Chongqing Medical University, Chongqing, China
- Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing, China
- National Clinical Research Center for Child Health and Disorders, Chongqing, China
- Chongqing Key Laboratory of Pediatrics, Chongqing, China
- * E-mail:
| | - Jinhua Cai
- Department of Radiology, Children’s Hospital of Chongqing Medical University, Chongqing, China
- Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing, China
- National Clinical Research Center for Child Health and Disorders, Chongqing, China
- Chongqing Key Laboratory of Pediatrics, Chongqing, China
| | - Huan Zheng
- Department of Radiology, Children’s Hospital of Chongqing Medical University, Chongqing, China
| | - Helin Zheng
- Department of Radiology, Children’s Hospital of Chongqing Medical University, Chongqing, China
| | - Qiurui Yang
- Department of Radiology, Children’s Hospital of Chongqing Medical University, Chongqing, China
| | - Changhong Yao
- Department of Radiology, Children’s Hospital of Chongqing Medical University, Chongqing, China
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Precht H, Outzen CB, Kusk MW, Bisgaard M, Waaler D. COMPARISON OF CONVENTIONAL HAND EXAMINATION ON SIX OPTIMISED DR SYSTEMS. RADIATION PROTECTION DOSIMETRY 2021; 194:27-35. [PMID: 33969425 PMCID: PMC8808537 DOI: 10.1093/rpd/ncab067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 03/23/2021] [Accepted: 04/13/2021] [Indexed: 06/12/2023]
Abstract
The purpose of this study was to investigate the challenges in comparing digital radiography (DR) systems from different vendors for various combinations of exposure factors in posterior-anterior hand radiographs. Image quality was evaluated for a range of tube voltages and tube current-time products using a technical contrast-detail (CDRAD) phantom and an anthropomorphic hand phantom. 900 technical CDRAD images were analysed providing quality figures of merit (IQFinv) and two experienced reporting radiographers using visual grading analysis (VGA) scored 108 anthropomorphic images. This study demonstrates the differences between the DR systems included. When compensating for variations in dose, Canon showed superior results for technical image quality and Fuji for visual image quality for a standard dose point at DR hand examination (ln(DAP) 1.1, 50 kV and 2.5 mAs).
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Affiliation(s)
| | - Claus Bjørn Outzen
- Health Sciences Research Centre, UCL University College, Niels Bohrs Allé 1, 5230 Odense M, Denmark
| | - Martin Weber Kusk
- Department of Radiology and Nuclear Medicine, University Hospital of Southwest Denmark, Finsensgade 35, 6700 Esbjerg, Denmark
| | - Malene Bisgaard
- Health Sciences Research Centre, UCL University College, Niels Bohrs Allé 1, 5230 Odense M, Denmark
| | - Dag Waaler
- Department of Health Sciences, Gjøvik, Norwegian University of Science and Technology, Teknologiveien 22, 2803 Gjøvik, Norway
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Gislason-Lee AJ. Patient X-ray exposure and ALARA in the neonatal intensive care unit: Global patterns. Pediatr Neonatol 2021; 62:3-10. [PMID: 33349597 DOI: 10.1016/j.pedneo.2020.10.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 08/03/2020] [Accepted: 10/30/2020] [Indexed: 10/22/2022] Open
Abstract
A literature review was conducted to determine norms for practice in neonatal intensive care units (NICU) around the world, given the harmful risks associated with radiation exposure at a very young age; risk of radiation-induced harm later in life increases with every X-ray image taken, more so for younger premature babies. Empirical studies including a measurement of radiation dose in a NICU, published after the year 2000 in a peer-reviewed journal, were collected. Measured doses to patients or X-ray phantoms, number of X-rays per stay and conclusions with recommendations made in response to these values were compared for 25 studies from around the world. The number of X-rays a patient underwent during a NICU stay ranged from 0 to 159. Younger, lower birth weight patients consistently had the greatest number of X-rays per stay. Recommended action based on measured dose ranged from extensive (to minimize risk to neonates) to minimal (to reduce risk) to none (because imaging benefits outweigh patient risk), with no consistent pattern linking recommended action with dose quantity. This demonstrates a broad range of interpretations of the As Low As Reasonably Achievable (ALARA) concept. These findings indicate a disparity in the response to neonatal X-ray dose concerns on a global scale, posing a public health risk to this particular neonatal population. More up-to-date imaging protocols and dose limits specifically for the NICU environment with standardized dose monitoring would help minimize this risk to achieve the public health goals of prevention and harm reduction.
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Affiliation(s)
- Amber J Gislason-Lee
- School of Allied Health Professions & Midwifery, Faculty of Health Studies, University of Bradford, UK.
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Del Vecchio A, Salerno S, Barbagallo M, Chirico G, Campoleoni M, Cannatà V, Genovese E, Granata C, Magistrelli A, Tomà P. Italian inter-society expert panel position on radiological exposure in Neonatal Intensive Care Units. Ital J Pediatr 2020; 46:159. [PMID: 33109231 PMCID: PMC7592562 DOI: 10.1186/s13052-020-00905-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/22/2020] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND In the recent years, clinical progress and better medical assistance for pregnant women, together with the introduction of new complex technologies, has improved the survival of preterm infants. However, this result requires frequent radiological investigations mostly represented by thoracic and abdominal radiographs in incubators. This document was elaborated by an expert panel Italian inter-society working group (Radiologists, Paediatricians, Medical Physicists) with the aim to assist healthcare practitioners in taking choices involving radiation exposures of new-born infants and to provide practical recommendations about justification and optimization in Neonatal Intensive Care Units. The adherence to these practice recommendations could ensure a high quality and patient safety. More complex and less common radiological practice, such as CT scan or fluoroscopy have been excluded. METHODS The consensus was reached starting from current good practice evidence shared by four scientific societies panel: AIFM (Italian Association of Physics in Medicine), SIN (Italian Neonatology Society), SIP (Italian Paediatric Society), SIRM (Italian Medical Radiology Society) in order to guarantee good standard practices for every professional involved in Neonatal Intensive Care Units (NICU). The report is divided into clinical and physical-dosimetric sections: clinical Indications, good practice in radiological exposures, devices, exposure parameters and modalities, patient positioning and immobilization, Reference Diagnostic Levels, operators and patient's radiation protection. Another important topic was the evaluation of the different incubators in order to understand if the consequences of the technological evolution have had an impact on the increase of the dose to the small patients, and how to choose the best device in terms of radiation protection. At the end the working group faced the problem of setting up the correct communication between clinicians and parents following the most recent indications of the international paediatric societies. RESULTS Taking into account the experience and expertise of 10 Italian Centres, the guideline sets out the criteria to ensure a high standard of neonatal care in NICU about procedures, facilities, recommended equipment, quality assurance, radiation protection measures for children and staff members and communication on radiation risk. CONCLUSIONS This document will allow a standardization of the approach to the exposures in NICU, although oriented to a flexible methodology.
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Affiliation(s)
- Antonella Del Vecchio
- Associazione Italiana di Fisica Medica (AIFM), Milan, Italy.
- Servizio di Fisica Sanitaria, IRCCS Ospedale San Raffaele, Via Olgettina, 60, 20132, Milan, Italy.
| | - Sergio Salerno
- Società Italiana di Radiologia Medica e Interventistica (SIRM), Milan, Italy
| | | | | | | | | | | | - Claudio Granata
- Società Italiana di Radiologia Medica e Interventistica (SIRM), Milan, Italy
| | - Andrea Magistrelli
- Società Italiana di Radiologia Medica e Interventistica (SIRM), Milan, Italy
| | - Paolo Tomà
- Società Italiana di Radiologia Medica e Interventistica (SIRM), Milan, Italy
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Survey of chest radiography systems: Any link between contrast detail measurements and visual grading analysis? Phys Med 2020; 76:62-71. [DOI: 10.1016/j.ejmp.2020.06.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 06/10/2020] [Accepted: 06/13/2020] [Indexed: 12/14/2022] Open
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Nitrosi A, Bertolini M, Chendi A, Trojani V, Canovi L, Pattacini P, Iori M. Physical characterization of a novel wireless DRX Plus 3543C using both a carbon nano tube (CNT) mobile x-ray system and a traditional x-ray system. Phys Med Biol 2020; 65:11NT02. [PMID: 32311679 DOI: 10.1088/1361-6560/ab8afb] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This work aims to characterize the novel DRX Plus 3543C detector in terms of detective quantum efficiency (DQE) using both a mobile x-ray system called Carestream DRX Revolution Nano and a traditional x-ray system (Carestream DRX Evolution). We used the commercial system DRX Revolution Nano, equipped with a new x-ray source based on CNT technology and field emission (FE) as the electron emitter (cathode). An innovative aspect of this device is its intrinsic selection of the focal spot size. We tested the system using three IEC-specified beam qualities (RQA3, 5 and 7) in terms of modulation transfer function (MTF), normalized noise power spectra (NNPS) and DQE as defined in the IEC 62220-1-1:2015. We compared the results obtained using DRX Revolution Nano and DRX Evolution with correlation and with Bland-Altman plots to study their agreement. RQA3 MTF is slightly lower than the RQA5 and 7 curves between 0.5 and 2.5 cycles mm-1. We measured MTF values of about 0.6 at 1 lp mm-1 and about 0.28 lp mm-1 at 2 lp mm-1. The NNPS curves show a decreasing trend with the energy regarding the DRX Revolution Nano. On the other hand, the DRX Evolution NNPS curve at RQA3 is greater than the one at RQA5, but the one at RQA5 is less than the one at RQA7. The DQE(0) ranged between about 0.82 (DRX Evolution at RQA3) and 0.54 (DRX Evolution at RQA7). As expected, the squared Pearson's correlation coefficients between the two x-ray tubes were always in an optimal agreement, and Bland-Altman plots confirmed a substantial equivalence between the two physical characterizations of the wireless detector. In conclusion, we can show that the dynamic focal selection of the system equipped with CNT does not play a substantial role in image quality compared to a traditional system in terms of physical characterisation of the detector in our measurement conditions.
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Affiliation(s)
- A Nitrosi
- Servizio di Fisica Medica, Azienda USL-IRCCS di Reggio Emilia, Reggio Emilia, Italy
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Comparison of HASTE with multiple signal averaging versus conventional turbo spin echo sequence: a new option for T2-weighted MRI of the female pelvis. Eur Radiol 2020; 30:3245-3253. [DOI: 10.1007/s00330-020-06686-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 12/09/2019] [Accepted: 01/29/2020] [Indexed: 10/25/2022]
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Al-Murshedi S, Peter Hogg, England A. Neonatal chest radiography: Influence of standard clinical protocols and radiographic equipment on pathology visibility and radiation dose using a neonatal chest phantom. Radiography (Lond) 2020; 26:282-287. [PMID: 32169312 DOI: 10.1016/j.radi.2020.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 02/15/2020] [Accepted: 02/19/2020] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Little is known about the variations in pathology visibility (PV) and their corresponding radiation dose values for neonatal chest radiography, between and within hospitals. Large variations in PV could influence the diagnostic outcome and the variations in radiation dose could affect the risk to patients. The aim of this study is to compare the PV and radiation dose for standard neonatal chest radiography protocols among a series of public hospitals. METHODS A Gammex 610 neonatal chest phantom was used to simulate the chest region of neonates. Radiographic acquisitions were conducted on 17 X-ray machines located in eight hospitals, utilising their current neonatal chest radiography protocols. Six qualified radiographers assessed PV visually using a relative visual grading analysis (VGA). Signal to noise ratios (SNR) and contrast to noise ratios (CNR) were measured as a measure of image quality (IQ). Incident air kerma (IAK) was measured using a solid-state dosimeter. RESULTS PV and radiation dose varied substantially between and within hospitals. For PV, the mean (range) VGA scores, between and within the hospitals, were 2.69 (2.00-3.50) and 2.73 (2.33-3.33), respectively. For IAK, the mean (range), between and within the hospitals, were 24.45 (8.11-49.94) μGy and 34.86 (22.26-49.94) μGy, respectively. CONCLUSION Between and within participating hospitals there was wide variation in the visibility of simulated pathology and radiation dose (IAK). IMPLICATIONS FOR PRACTICE X-ray units with lower PV and higher doses require optimisation of their standard clinical protocols. Institutions which can offer acceptable levels of PV but with lower radiation doses should help facilitate national optimisation processes.
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Affiliation(s)
- S Al-Murshedi
- University of ALZahraa for Women, College of Health and Medical Technology, Karbala, Iraq.
| | - Peter Hogg
- School of Health and Society, University of Salford, Salford, M6 6PU, United Kingdom
| | - A England
- School of Health and Society, University of Salford, Salford, M6 6PU, United Kingdom
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Schäfer SB, Papst S, Fiebich M, Rudolph C, de Laffolie J, Krombach GA. Modification of chest radiography exposure parameters using a neonatal chest phantom. Pediatr Radiol 2020; 50:28-37. [PMID: 31583441 DOI: 10.1007/s00247-019-04522-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 07/09/2019] [Accepted: 09/02/2019] [Indexed: 11/28/2022]
Abstract
BACKGROUND The acquisition of chest radiographs in neonates is of critical importance in diagnostics because of the risk of respiratory distress syndrome and pneumothorax in preterm infants. OBJECTIVE To achieve a dose reduction while preserving a diagnostic image quality for chest radiographs of neonates. MATERIALS AND METHODS All radiographs, generated on a fully digital X-ray unit by using a neonatal chest phantom, were evaluated under variation of the tube voltage (40-70 kV) and mAs levels (1-10.2 mAs) with and without an additional 0.1-mm copper (Cu) filtration. Noise, contrast and contrast-to-noise ratio for bronchus, heart, lungs and vessels were determined. Visual assessment of the image quality was carried out by three radiologists using a Likert scale. To evaluate a maximally possible dose reduction, the dose of the radiographs with still acceptable image quality at a minimal dose was compared to the dose of the radiographs with the standard settings used in clinical routine. RESULTS The noise showed decreasing values with increasing dose, while the contrast values were increased. For the contrast-to-noise ratio, a digressive course of the values as a function of the tube voltage was found. The visual evaluation of image quality showed the best evaluation of the structures at the lowest possible dose in the settings (44 kV, 3.36 mAs) with copper filtration and in the settings (44 kV, 1.56 mAs) without copper filtration. A maximum dose reduction from 8.29 μSv to 2.21 μSv (about 73%) was obtained. CONCLUSION A dose reduction while preserving diagnostic image quality in a digital X-ray system is generally possible by reducing the tube voltage and simultaneous adaptation of the mAs settings.
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Affiliation(s)
- Stefan B Schäfer
- Department of Diagnostic and Interventional Radiology, University Hospital Giessen, Justus-Liebig University, Klinikstrasse 33, 35392, Giessen, Germany.
| | - Sabine Papst
- Department of Diagnostic and Interventional Radiology, University Hospital Giessen, Justus-Liebig University, Klinikstrasse 33, 35392, Giessen, Germany.,Department of Pediatric Radiology, University Hospital Giessen, Justus-Liebig University, 35392, Giessen, Germany
| | - Martin Fiebich
- Institute of Medical Physics and Radiation Protection, University of Applied Sciences, 35392, Giessen, Germany
| | - Claudia Rudolph
- Department of Pediatric Radiology, University Hospital Giessen, Justus-Liebig University, 35392, Giessen, Germany
| | - Jan de Laffolie
- Department of General Pediatrics and Neonatology, University Hospital Giessen, Justus-Liebig University, 35392, Giessen, Germany
| | - Gabriele A Krombach
- Department of Diagnostic and Interventional Radiology, University Hospital Giessen, Justus-Liebig University, Klinikstrasse 33, 35392, Giessen, Germany.,Department of Pediatric Radiology, University Hospital Giessen, Justus-Liebig University, 35392, Giessen, Germany
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Irnstorfer N, Unger E, Hojreh A, Homolka P. An anthropomorphic phantom representing a prematurely born neonate for digital x-ray imaging using 3D printing: Proof of concept and comparison of image quality from different systems. Sci Rep 2019; 9:14357. [PMID: 31591433 PMCID: PMC6779877 DOI: 10.1038/s41598-019-50925-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 09/19/2019] [Indexed: 02/06/2023] Open
Abstract
An anthropomorphic phantom for image optimization in neonatal radiography was developed, and its usability in optimizing image acquisition and processing demonstrated. The phantom was designed to mimic a patient image of a prematurely born neonate. A clinical x-ray (neonate <1 kg) taken with an effective dose of 11 µSv on a needle-crystal storage phosphor system was retrospectively selected from anonymized images as an appropriate template representing a standard case in neonatology imaging. The low dose level used in clinical imaging results in high image noise content. Therefore, the image had to be processed using structure preserving noise reduction. Pixel values were related to printing material thickness to result in a similar attenuation pattern as the original patient including support mattress. A 3D model generating a similar x-ray attenuation pattern on an image detector as a patient was derived accounting for beam hardening and perspective, and printed using different printing technologies. Best printing quality was achieved using a laser stereolithography printer. Phantom images from different digital radiography systems used in neonatal imaging were compared. Effects of technology, image processing, and radiation dose on diagnostic image quality can be assessed for otherwise identical anthropomorphic neonatal images not possible with patient images, facilitating optimization and standardization of imaging parameters and image appearance.
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Affiliation(s)
- Nikolaus Irnstorfer
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Ewald Unger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Azadeh Hojreh
- Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Peter Homolka
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
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Needle-based storage-phosphor detector radiography is superior to a conventional powder-based storage phosphor detector and a high-resolution screen-film system in small patients (budgerigars and mice). Sci Rep 2019; 9:10057. [PMID: 31296929 PMCID: PMC6624299 DOI: 10.1038/s41598-019-46546-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 07/01/2019] [Indexed: 11/09/2022] Open
Abstract
This method comparison study used radiographs of 20 mice and 20 budgerigars to investigate comparability between computed radiography (CR) and high-resolution screen-film systems and study the effects of reduced radiation doses on image quality of digital radiographs of small patients. Exposure settings used with the mammography screen-film system (SF) were taken as baseline settings. A powder-based storage-phosphor system (CRP) and a needle-based storage-phosphor system (CRN) were used with the same settings (D/100%) and half the detector dose (D/50%). Using a scoring system four reviewers assessed five criteria per species covering soft tissue and bone structures. Results were evaluated for differences between reviewers (interobserver variability), systems and settings (intersystem variability, using visual grading characteristic analysis). Correlations were significant (p ≤ 0.05) for interobserver variability in 86.7% of the cases. Correlation coefficients ranged from 0.206 to 0.772. For mice and budgerigars, the CRN system was rated as superior to the SF and CRP system for most criteria, being significant in two cases each. Comparing the SF and CRP system, the conventional method scored higher for all criteria, in one case significantly. For both species and both digital systems, dose reduction to 50% resulted in significantly worse scores for most criteria. In summary, the needle-based storage-phosphor technique proved to be superior compared to the conventional storage-phosphor and mammography screen-film system. Needle-based detector systems are suitable substitutes for high-resolution screen–film systems when performing diagnostic imaging of small patients. Dose reduction to 50% of the corresponding dose needed in high-resolution film-screen systems cannot be recommended.
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Coyner AS, Swan R, Campbell JP, Ostmo S, Brown JM, Kalpathy-Cramer J, Kim SJ, Jonas KE, Chan RVP, Chiang MF. Automated Fundus Image Quality Assessment in Retinopathy of Prematurity Using Deep Convolutional Neural Networks. Ophthalmol Retina 2019; 3:444-450. [PMID: 31044738 DOI: 10.1016/j.oret.2019.01.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 01/12/2019] [Accepted: 01/23/2019] [Indexed: 10/27/2022]
Abstract
PURPOSE Accurate image-based ophthalmic diagnosis relies on fundus image clarity. This has important implications for the quality of ophthalmic diagnoses and for emerging methods such as telemedicine and computer-based image analysis. The purpose of this study was to implement a deep convolutional neural network (CNN) for automated assessment of fundus image quality in retinopathy of prematurity (ROP). DESIGN Experimental study. PARTICIPANTS Retinal fundus images were collected from preterm infants during routine ROP screenings. METHODS Six thousand one hundred thirty-nine retinal fundus images were collected from 9 academic institutions. Each image was graded for quality (acceptable quality [AQ], possibly acceptable quality [PAQ], or not acceptable quality [NAQ]) by 3 independent experts. Quality was defined as the ability to assess an image confidently for the presence of ROP. Of the 6139 images, NAQ, PAQ, and AQ images represented 5.6%, 43.6%, and 50.8% of the image set, respectively. Because of low representation of NAQ images in the data set, images labeled NAQ were grouped into the PAQ category, and a binary CNN classifier was trained using 5-fold cross-validation on 4000 images. A test set of 2109 images was held out for final model evaluation. Additionally, 30 images were ranked from worst to best quality by 6 experts via pairwise comparisons, and the CNN's ability to rank quality, regardless of quality classification, was assessed. MAIN OUTCOME MEASURES The CNN performance was evaluated using area under the receiver operating characteristic curve (AUC). A Spearman's rank correlation was calculated to evaluate the overall ability of the CNN to rank images from worst to best quality as compared with experts. RESULTS The mean AUC for 5-fold cross-validation was 0.958 (standard deviation, 0.005) for the diagnosis of AQ versus PAQ images. The AUC was 0.965 for the test set. The Spearman's rank correlation coefficient on the set of 30 images was 0.90 as compared with the overall expert consensus ranking. CONCLUSIONS This model accurately assessed retinal fundus image quality in a comparable manner with that of experts. This fully automated model has potential for application in clinical settings, telemedicine, and computer-based image analysis in ROP and for generalizability to other ophthalmic diseases.
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Affiliation(s)
- Aaron S Coyner
- Department of Medical Informatics and Clinical Epidemiology, Oregon Health and Science University, Portland, Oregon
| | - Ryan Swan
- Department of Medical Informatics and Clinical Epidemiology, Oregon Health and Science University, Portland, Oregon
| | - J Peter Campbell
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon
| | - Susan Ostmo
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon
| | - James M Brown
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
| | - Jayashree Kalpathy-Cramer
- Department of Medical Informatics and Clinical Epidemiology, Oregon Health and Science University, Portland, Oregon; Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts; Massachusetts General Hospital and Brigham and Women's Hospital Center for Clinical Data Science, Boston, Massachusetts
| | - Sang Jin Kim
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon; Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Karyn E Jonas
- Department of Ophthalmology, University of Illinois at Chicago, Chicago, Illinois
| | - R V Paul Chan
- Department of Ophthalmology, University of Illinois at Chicago, Chicago, Illinois
| | - Michael F Chiang
- Department of Medical Informatics and Clinical Epidemiology, Oregon Health and Science University, Portland, Oregon; Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon.
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