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Tanaka N, Yoon Y. Effect of anti-scatter grids on the image improvement factor in digital radiography for various phantom thicknesses and irradiation fields. Phys Eng Sci Med 2023; 46:1187-1192. [PMID: 37336831 DOI: 10.1007/s13246-023-01285-w] [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: 01/06/2023] [Accepted: 05/22/2023] [Indexed: 06/21/2023]
Abstract
Digital radiography (DR) is used to acquire digital images with a consistent image brightness under different exposures and in the presence of various anti-scatter grids. This study effectively evaluates the image improvement factor and the conventional physical imaging properties, such as grid selectivity, contrast improvement ratio, and grid exposure factor. Various grids and acrylic phantoms of thicknesses 20 cm and 12 cm were used in this evaluation to simulate the pelvis and lumbar spine, and the cervical spine, respectively. Applied irradiation fields were adjusted according to the simulated body parts. Eight grids (four at 40 cm-1 strip frequency with grid ratios of 6:1, 8:1, 10:1, and 12:1, and four at 60 cm-1 strip frequency with grid ratios of 8:1, 10:1, 12:1, and 14:1) were used in this study. The grid selectivity, contrast improvement ratio, and grid exposure factor increased with higher grid ratios. At a constant grid ratio, these three parameters exhibited higher values at lower strip frequency (40 cm-1) than at higher strip frequency (60 cm-1). The change in the image improvement factor of the simulated cervical spine with respect to the grid was smaller than those of the simulated pelvis and lumbar spine. Our results suggested that the image improvement factor is a useful index for selecting grids according to object thickness at a constant exposure in DR systems.
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Affiliation(s)
- Nobukazu Tanaka
- Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
| | - Yongsu Yoon
- Department of Multidisciplinary Radiological Science, The Graduate School of Dongseo University, Busan, Republic of Korea
- Center for Radiological Environment & Health Science, Dongseo University, Busan, Republic of Korea
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Onodera S, Kondo Y, Ishizawa S, Kawabata T, Ishii H. Usefulness of copper filters in digital chest radiography based on the relationship between effective detective quantum efficiency and deep learning-based segmentation accuracy of the tumor area. Radiol Phys Technol 2023; 16:299-309. [PMID: 37046154 DOI: 10.1007/s12194-023-00719-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 04/09/2023] [Accepted: 04/10/2023] [Indexed: 04/14/2023]
Abstract
This study aimed to determine the optimal radiographic conditions for detecting lesions on digital chest radiographs using an indirect conversion flat-panel detector with a copper (Cu) filter. First, we calculated the effective detective quantum efficiency (DQE) by considering clinical conditions to evaluate the image quality. We then measured the segmentation accuracy using a U-net convolutional network to verify the effectiveness of the Cu filter. We obtained images of simulated lung tumors using 10-mm acrylic spheres positioned at the right lung apex and left middle lung of an adult chest phantom. The Dice coefficient was calculated as the similarity between the output and learning images to evaluate the accuracy of tumor area segmentation using U-net. Our results showed that effective DQE was higher in the following order up to the spatial frequency of 2 cycles/mm: 120 kV + no Cu, 120 kV + Cu 0.1 mm, and 120 kV + Cu 0.2 mm. The segmented region was similar to the true region for mass-area extraction in the left middle lobe. The lesion segmentation in the upper right lobe with 120 kV + no Cu and 120 kV + Cu 0.1 mm was less successful. However, adding a Cu filter yielded reproducible images with high Dice coefficients, regardless of the tumor location. We confirmed that adding a Cu filter decreases the X-ray absorption efficiency while improving the signal-to-noise ratio (SNR). Furthermore, artificial intelligence accurately segments low-contrast lesions.
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Affiliation(s)
- Shu Onodera
- Department of Radiology Division of Medical Technology, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan.
- Graduate School of Health Sciences, Niigata University, 746 Asahimachidori 2bancho Chuo-ku, Niigata City, Niigata, 951-8518, Japan.
| | - Yohan Kondo
- Graduate School of Health Sciences, Niigata University, 746 Asahimachidori 2bancho Chuo-ku, Niigata City, Niigata, 951-8518, Japan
| | - Shoko Ishizawa
- Department of Radiology Division of Medical Technology, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Tomoyoshi Kawabata
- Department of Radiology Division of Medical Technology, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Hiroki Ishii
- Department of Radiology Division of Medical Technology, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
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Chang CT, Chou MC. Comparison of Non-Uniform Image Quality Caused by Anode Heel Effect between Two Digital Radiographic Systems Using a Circular Step-Wedge Phantom and Mutual Information. ENTROPY (BASEL, SWITZERLAND) 2022; 24:1781. [PMID: 36554186 PMCID: PMC9778271 DOI: 10.3390/e24121781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 11/29/2022] [Accepted: 12/05/2022] [Indexed: 06/17/2023]
Abstract
The purpose of this study was to compare non-uniform image quality caused by the anode heel effect between two radiographic systems using a circular step-wedge (CSW) phantom and the normalized mutual information (nMI) metric. Ten repeated radiographic images of the CSW and contrast-detail resolution (CDR) phantoms were acquired from two digital radiographic systems with 16- and 12-degree anode angles, respectively, using various kVp and mAs. To compare non-uniform image quality, the CDR phantom was physically rotated at different orientations, and the directional nMI metrics were calculated from the CSW images. The directional visible ratio (VR) metrics were calculated from the CDR images. Analysis of variance (ANOVA) was performed to understand whether the nMI metric significantly changed with kVp, mAs, and orientations with Bonferroni correction. Mann-Whitney's U test was performed to compare the metrics between the two systems. Contrary to the VR metrics, the nMI metrics significantly changed with orientations in both radiographic systems. In addition, the system with the 12-degree anode angle exhibited less uniform image quality compared to the system with the 16-degree anode angle. A CSW phantom using the directional nMI metric can be significantly helpful to compare non-uniform image quality between two digital radiographic systems.
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Affiliation(s)
- Ching-Ting Chang
- Department of Medical Imaging, Kaohsiung Medical University Hospital, Kaohsiung 80708, Taiwan
- Department of Radiology, Kaohsiung Medical University Gangshan Hospital, Kaohsiung 82060, Taiwan
- Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Ming-Chung Chou
- Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- Center for Big Data Research, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 80708, Taiwan
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New Software for DQE Calculation in Digital Mammography Compliant with IEC 62220–1-2. J Digit Imaging 2022; 35:1069-1078. [PMID: 36104636 PMCID: PMC9582097 DOI: 10.1007/s10278-021-00546-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 10/26/2021] [Accepted: 11/11/2021] [Indexed: 12/03/2022] Open
Abstract
Significant improvements in mammography systems have been achieved with the introduction of active matrix flat-panel digital detectors. The advent of this technology also makes it possible to implement computational methods for quantitative image analysis. This study describes new software created to perform detective quantum efficiency (DQE) calculations fully compliant with the IEC 62220–1-2 standard. Python-based software was developed that contains modules to calculate inverse conversion function, modulation transfer function (MTF), noise power spectrum (NPS), and DQE itself. A graphical user interface (GUI) and further add-ons make this software more user-friendly. Results are immediately displayed diagrammatically, and complete output data are exported to a .csv file. The code is available freely, as a compiled, executable file (.exe). The program was successfully tested using DICOM images obtained from mammography units from different manufacturers. This study also includes validation of the new software, based on comparisons of results obtained for the same set of data with two other, freely available programs.
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Abdi AJ, Mussmann BR, Mackenzie A, Gerke O, Klaerke B, Andersen PE. Quantitative Image Quality Metrics of the Low-Dose 2D/3D Slot Scanner Compared to Two Conventional Digital Radiography X-ray Imaging Systems. Diagnostics (Basel) 2021; 11:1699. [PMID: 34574041 PMCID: PMC8472127 DOI: 10.3390/diagnostics11091699] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/14/2021] [Accepted: 09/15/2021] [Indexed: 11/16/2022] Open
Abstract
The aim of this study was to determine the quantitative image quality metrics of the low-dose 2D/3D EOS slot scanner X-ray imaging system (LDSS) compared with conventional digital radiography (DR) X-ray imaging systems. The effective detective quantum efficiency (eDQE) and effective noise quantum equivalent (eNEQ) were measured using chest and knee protocols. METHODS A Nationwide Evaluation of X-ray Trends (NEXT) of a chest adult phantom and a PolyMethylmethacrylate (PMMA) phantom were used for the chest and knee protocols, respectively. Quantitative image quality metrics, including effective normalised noise power spectrum (eNNPS), effective modulation transfer function (eMTF), eDQE and eNEQ of the LDSS and DR imaging systems were assessed and compared. RESULTS In the chest acquisition, the LDSS imaging system achieved significantly higher eNEQ and eDQE than the DR imaging systems at lower and higher spatial frequencies (0.001 ≤ p ≤ 0.044). For the knee acquisition, the LDSS imaging system also achieved significantly higher eNEQ and eDQE than the DR imaging systems at lower and higher spatial frequencies (0.001 ≤ p ≤ 0.002). However, there was no significant difference in eNEQ and eDQE between DR systems 1 and 2 at lower and higher spatial frequencies (0.10 < p < 1.00) for either chest or knee protocols. CONCLUSION The LDSS imaging system performed well compared to the DR systems. Thus, we have demonstrated that the LDSS imaging system has the potential to be used for clinical diagnostic purposes.
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Affiliation(s)
- Ahmed Jibril Abdi
- Department of Clinical Research, University of Southern Denmark, 5000 Odense C, Denmark; (B.R.M.); (O.G.); (P.E.A.)
- Region of Southern Denmark, Clinical Engineering Department, Area of Diagnostic Radiology, 5000 Odense C, Denmark;
| | - Bo R. Mussmann
- Department of Clinical Research, University of Southern Denmark, 5000 Odense C, Denmark; (B.R.M.); (O.G.); (P.E.A.)
- Department of Radiology, Odense University Hospital, 5000 Odense C, Denmark
| | - Alistair Mackenzie
- National Coordinating Centre for the Physics of Mammography, Royal Surrey NHS, Foundation Trust, Guildford GU2 7XX, UK;
| | - Oke Gerke
- Department of Clinical Research, University of Southern Denmark, 5000 Odense C, Denmark; (B.R.M.); (O.G.); (P.E.A.)
- Department of Nuclear Medicine, Odense University Hospital, 5000 Odense C, Denmark
| | - Benedikte Klaerke
- Region of Southern Denmark, Clinical Engineering Department, Area of Diagnostic Radiology, 5000 Odense C, Denmark;
| | - Poul Erik Andersen
- Department of Clinical Research, University of Southern Denmark, 5000 Odense C, Denmark; (B.R.M.); (O.G.); (P.E.A.)
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Determination of DQE as a quantitative assessment of detectors in digital mammography: Measurements and calculation in practice. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2021. [DOI: 10.2478/pjmpe-2021-0027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Abstract
Introduction: Advances in digital detector technology and methods of image presentation in digital mammography now offer the possibility of implementing mathematical assessment methods to quantitative image analysis. The aim of this work was to develop new software to simplify the application of the existing international standard for DQE in digital mammography and show in detail how it can be applied, using a Siemens Mammomat Inspiration as a model.
Material and methods: Consistent with the IEC standard a 2 mm Al filter at the tube exit and images in DICOM format as raw data, without applying any additional post-processing were used. Measurements were performed for W/Rh anode/filter combination and different tube voltage values (26 ÷ 34 kV) without any anti-scatter grid. To verify new software doses ranging from 20-600 µGy were used in measurements. Exposure (air kerma) was measured using a calibrated radiation meter (Piranha Black 457, RTI Electronics AB, Sweden). MTF was determined, using an edge test device constructed specifically for this work.
Results: It has been demonstrated that with the new software the DQE can be measured with the accuracy required by the international standard IEC 62220-1-2. DQE has been presented as a function of spatial frequency for W/Rh anode/filter combination and different tube voltage.
Conclusions: New software was used successfully to analyze image quality parameters for the Siemens Mammomat Inspiration detector. This was done on the basis of an internationally accepted methodology. In the next step, mammographs with different detector types can be compared.
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Evaluation of Non-Uniform Image Quality Caused by Anode Heel Effect in Digital Radiography Using Mutual Information. ENTROPY 2021; 23:e23050525. [PMID: 33922996 PMCID: PMC8145656 DOI: 10.3390/e23050525] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/24/2021] [Accepted: 04/24/2021] [Indexed: 11/17/2022]
Abstract
Anode heel effects are known to cause non-uniform image quality, but no method has been proposed to evaluate the non-uniform image quality caused by the heel effect. Therefore, the purpose of this study was to evaluate non-uniform image quality in digital radiographs using a novel circular step-wedge (CSW) phantom and normalized mutual information (nMI). All X-ray images were acquired from a digital radiography system equipped with a CsI flat panel detector. A new acrylic CSW phantom was imaged ten times at various kVp and mAs to evaluate overall and non-uniform image quality with nMI metrics. For comparisons, a conventional contrast-detail resolution phantom was imaged ten times at identical exposure parameters to evaluate overall image quality with visible ratio (VR) metrics, and the phantom was placed in different orientations to assess non-uniform image quality. In addition, heel effect correction (HEC) was executed to elucidate the impact of its effect on image quality. The results showed that both nMI and VR metrics significantly changed with kVp and mAs, and had a significant positive correlation. The positive correlation is suggestive that the nMI metrics have a similar performance to the VR metrics in assessing the overall image quality of digital radiographs. The nMI metrics significantly changed with orientations and also significantly increased after HEC in the anode direction. However, the VR metrics did not change significantly with orientations or with HEC. The results indicate that the nMI metrics were more sensitive than the VR metrics with regards to non-uniform image quality caused by the anode heel effect. In conclusion, the proposed nMI metrics with a CSW phantom outperformed the conventional VR metrics in detecting non-uniform image quality caused by the heel effect, and thus are suitable for quantitatively evaluating non-uniform image quality in digital radiographs with and without HEC.
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Yalcin A, Olgar T, Sancak T, Atac GK, Akyar S. Correlation between physical measurements and observer evaluations of image quality in digital chest radiography. Med Phys 2020; 47:3935-3944. [DOI: 10.1002/mp.14244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 04/27/2020] [Accepted: 05/01/2020] [Indexed: 11/06/2022] Open
Affiliation(s)
- Asena Yalcin
- Institute of Nuclear Sciences Ankara University Ankara 06100 Turkey
| | - Turan Olgar
- Institute of Nuclear Sciences Ankara University Ankara 06100 Turkey
- Faculty of Engineering Department of Engineering Physics Ankara University Ankara 06100 Turkey
| | - Tanzer Sancak
- Department of Radiology TOBB University of Economics and Technology Hospital Ankara Turkey
| | - Gokce Kaan Atac
- Faculty of Medicine Department of Radiology Ufuk University Ankara Turkey
| | - Serdar Akyar
- Department of Radiology Ankara University School of Medicine Ankara Turkey
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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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Bertolini M, Trojani V, Nitrosi A, Iori M, Sassatelli R, Ortenzia O, Ghetti C. Characterization of GE discovery IGS 740 angiography system by means of channelized Hotelling observer (CHO). ACTA ACUST UNITED AC 2019; 64:095002. [DOI: 10.1088/1361-6560/ab144c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Bor D, Guven A, Yusuf AR, Birgul O, Yuksel S, Yalcin A, Marshall N, Olgar T. A modified formulation of eDQE for digital radiographic imaging. Radiat Phys Chem Oxf Engl 1993 2019. [DOI: 10.1016/j.radphyschem.2018.10.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Wood TJ, Moore CS, Saunderson JR, Beavis AW. Measurement of effective detective quantum efficiency for a photon counting scanning mammography system and comparison with two flat panel full-field digital mammography systems. Phys Med Biol 2018; 63:025025. [PMID: 29260730 DOI: 10.1088/1361-6560/aaa307] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Effective detective quantum efficiency (eDQE) describes the resolution and noise properties of an imaging system along with scatter and primary transmission, all measured under clinically appropriate conditions. Effective dose efficiency (eDE) is the eDQE normalised to mean glandular dose and has been proposed as a useful metric for the optimisation of clinical imaging systems. The aim of this study was to develop a methodology for measuring eDQE and eDE on a Philips microdose mammography (MDM) L30 photon counting scanning system, and to compare performance with two conventional flat panel systems. A custom made lead-blocker was manufactured to enable the accurate determination of dose measurements, and modulation transfer functions were determined free-in-air at heights of 2, 4 and 6 cm above the breast support platform. eDQE were calculated for a Philips MDM L30, Hologic Dimensions and Siemens Inspiration digital mammography system for 2, 4 and 6 cm thick poly(methyl methacrylate) (PMMA). The beam qualities (target/filter and kilovoltage) assessed were those selected by the automatic exposure control, and anti-scatter grids were used where available. Measurements of eDQE demonstrate significant differences in performance between the slit- and scan-directions for the photon counting imaging system. MTF has been shown to be the limiting factor in the scan-direction, which results in a rapid fall in eDQE at mid-to-high spatial frequencies. A comparison with two flat panel mammography systems demonstrates that this may limit image quality for small details, such as micro-calcifications, which correlates with a more conventional image quality assessment with the CDMAM phantom. eDE has shown the scanning photon counting system offers superior performance for low spatial frequencies, which will be important for the detection of large low contrast masses. Both eDQE and eDE are proposed as useful metrics that should enable optimisation of the Philips MDM L30.
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Affiliation(s)
- Tim J Wood
- Radiation Physics Department, Queen's Centre for Oncology and Haematology, Castle Hill Hospital, Hull and East Yorkshire Hospitals NHS Trust, Castle Road, Hull, HU16 5JQ, United Kingdom. Faculty of Science, University of Hull, Cottingham Road, Hull, HU6 7RX, United Kingdom
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Samei E, Ikejimba LC, Harrawood BP, Rong J, Cunningham IA, Flynn MJ. Report of AAPM Task Group 162: Software for planar image quality metrology. Med Phys 2018; 45:e32-e39. [DOI: 10.1002/mp.12718] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 10/31/2017] [Accepted: 11/30/2017] [Indexed: 12/17/2022] Open
Affiliation(s)
- Ehsan Samei
- Carl E. Ravin Advanced Imaging Laboratories; Medical Physics Graduate Program; Departments of Radiology, Biomedical Engineering, Physics, and Electrical and Computer Engineering; Clinical Imaging Physics Group; Duke University; 2424 Erwin Road Durham NC 27710 USA
| | - Lynda C. Ikejimba
- Carl E. Ravin Advanced Imaging Laboratories; Medical Physics Graduate Program; Department of Radiology; Duke University; 2424 Erwin Road Durham NC 27710 USA
| | - Brian P. Harrawood
- Carl E. Ravin Advanced Imaging Laboratories; Department of Radiology; Duke University; 2424 Erwin Road Durham NC 27710 USA
| | - John Rong
- Department of Imaging Physics; UT MD Anderson Cancer Center; 1400 Pressler St, Unit 1472 Houston TX 77030 USA
| | - Ian A. Cunningham
- Robarts Research Institute; Western University; 1151 Richmind St N London ON N6A 5B7 Canada
| | - Michael J. Flynn
- Department of Diagnostic Radiology; Henry Ford Health System; One Ford Pl, 3F Detroit MI 48202 USA
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Moore CS, Wood TJ, Avery G, Balcam S, Needler L, Joshi H, Saunderson JR, Beavis AW. Automatic exposure control calibration and optimisation for abdomen, pelvis and lumbar spine imaging with an Agfa computed radiography system. Phys Med Biol 2016; 61:N551-N564. [DOI: 10.1088/0031-9155/61/21/n551] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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15
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Clavel AH, Monnin P, Létang JM, Verdun FR, Darbon A. CHARACTERISING THE EOS SLOT-SCANNING SYSTEM WITH THE EFFECTIVE DETECTIVE QUANTUM EFFICIENCY. RADIATION PROTECTION DOSIMETRY 2016; 169:319-324. [PMID: 26538617 DOI: 10.1093/rpd/ncv451] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
As opposed to the standard detective quantum efficiency (DQE), effective DQE (eDQE) is a figure of merit that allows comparing the performances of imaging systems in the presence of scatter rejection devices. The geometry of the EOS™ slot-scanning system is such that the detector is self-collimated and rejects scattered radiation. In this study, the EOS system was characterised using the eDQE in imaging conditions similar to those used in clinical practice: with phantoms of different widths placed in the X-ray beam, for various incident air kerma and tube voltages corresponding to the phantom thickness. Scatter fractions in EOS images were extremely low, around 2 % for all configurations. Maximum eDQE values spanned 9-14.8 % for a large range of air kerma at the detector plane from 0.01 to 1.34 µGy. These figures were obtained with non-optimised EOS setting but still over-performed most of the maximum eDQEs recently assessed for various computed radiology and digital radiology systems with antiscatter grids.
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Affiliation(s)
- A H Clavel
- Institute of Radiation Physics, CHUV, Rue du Grand-Pré 1, CH-1007 Lausanne, Switzerland Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Claude Bernard Lyon 1, Centre Léon Bérard, Lyon, France EOS imaging, 10 rue Mercœur, 75011 Paris, France
| | - P Monnin
- Institute of Radiation Physics, CHUV, Rue du Grand-Pré 1, CH-1007 Lausanne, Switzerland
| | - J M Létang
- Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Claude Bernard Lyon 1, Centre Léon Bérard, Lyon, France
| | - F R Verdun
- Institute of Radiation Physics, CHUV, Rue du Grand-Pré 1, CH-1007 Lausanne, Switzerland
| | - A Darbon
- EOS imaging, 10 rue Mercœur, 75011 Paris, France
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Lee KL, Bernardo M, Ireland TA. Benchmarking the performance of fixed-image receptor digital radiography systems. Part 2: system performance metric. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2016; 39:463-76. [PMID: 27222199 DOI: 10.1007/s13246-016-0439-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Accepted: 03/25/2016] [Indexed: 11/25/2022]
Abstract
This is part two of a two-part study in benchmarking system performance of fixed digital radiographic systems. The study compares the system performance of seven fixed digital radiography systems based on quantitative metrics like modulation transfer function (sMTF), normalised noise power spectrum (sNNPS), detective quantum efficiency (sDQE) and entrance surface air kerma (ESAK). It was found that the most efficient image receptors (greatest sDQE) were not necessarily operating at the lowest ESAK. In part one of this study, sMTF is shown to depend on system configuration while sNNPS is shown to be relatively consistent across systems. Systems are ranked on their signal-to-noise ratio efficiency (sDQE) and their ESAK. Systems using the same equipment configuration do not necessarily have the same system performance. This implies radiographic practice at the site will have an impact on the overall system performance. In general, systems are more dose efficient at low dose settings.
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Affiliation(s)
- Kam L Lee
- Biomedical Technology Services, Princess Alexandra Hospital, Health Support Queensland, 199 Ipswich Road, Woolloongabba, 4102, QLD, Australia.
| | - Michael Bernardo
- Biomedical Technology Services, Health Support Queensland, Fortitude Valley, Australia
| | - Timothy A Ireland
- Biomedical Technology Services, Gold Coast University Hospital, Health Support Queensland, Southport, Australia
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Benchmarking the performance of fixed-image receptor digital radiographic systems part 1: a novel method for image quality analysis. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2016; 39:453-62. [PMID: 27222198 DOI: 10.1007/s13246-016-0440-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Accepted: 03/25/2016] [Indexed: 10/21/2022]
Abstract
This is the first part of a two-part study in benchmarking the performance of fixed digital radiographic general X-ray systems. This paper concentrates on reporting findings related to quantitative analysis techniques used to establish comparative image quality metrics. A systematic technical comparison of the evaluated systems is presented in part two of this study. A novel quantitative image quality analysis method is presented with technical considerations addressed for peer review. The novel method was applied to seven general radiographic systems with four different makes of radiographic image receptor (12 image receptors in total). For the System Modulation Transfer Function (sMTF), the use of grid was found to reduce veiling glare and decrease roll-off. The major contributor in sMTF degradation was found to be focal spot blurring. For the System Normalised Noise Power Spectrum (sNNPS), it was found that all systems examined had similar sNNPS responses. A mathematical model is presented to explain how the use of stationary grid may cause a difference between horizontal and vertical sNNPS responses.
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Kloth JK, Neumann R, von Stillfried E, Stiller W, Burkholder I, Kauczor HU, Ewerbeck V, Weber MA. Quality-controlled dose-reduction of pelvic X-ray examinations in infants with hip dysplasia. Eur J Radiol 2015; 85:233-238. [PMID: 26724671 DOI: 10.1016/j.ejrad.2015.11.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 11/05/2015] [Accepted: 11/12/2015] [Indexed: 10/22/2022]
Abstract
BACKGROUND Digital plain radiography (DR) examinations of the pelvis are frequently performed in infants with hip dysplasia. OBJECTIVE The purpose was to reduce the radiation dose and to determine objective quality control criteria to ensure accurate assessment. This seems feasible because of higher quantum efficiency of DR and easy assessable anatomical structures for most orthopaedic measurements. MATERIALS AND METHODS Institutional review board approval was obtained. In this prospective randomized study, 264 patients underwent X-ray examination of the pelvis with standard and reduced dose. The evaluation of the plain-radiographs was conducted using the following criteria: acetabular and center edge angle, closing of the epiphyseal plates and maturation of the femoral head. Two radiologists evaluated these criteria using a score ranging from 1 (definitely assessable) to 4 (not assessable). If a single criterion had been evaluated with a score of 3 or more points or more than 2 criteria with 2 points, the radiograph was scored as "not assessable". The statistical analysis was conducted as non-inferiority-trial. RESULTS Five (1.9%) examined X-rays were scored as not assessable. There was no statistical inferiority between the examinations with standard (4.57 μSv) or reduced dose (3.06 μSv). Also, the individual evaluation of the defined criteria was dose-independent. CONCLUSION The adequate evaluation of hip dysplasia in children and young adults on pelvic radiographs is possible with reduced radiation dose, by simple using an exposure class of 800 instead of 400.
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Affiliation(s)
- Jost Karsten Kloth
- Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, Heidelberg D-69120, Germany.
| | - Regina Neumann
- Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, Heidelberg D-69120, Germany.
| | - Eva von Stillfried
- Orthopedic and Trauma Surgery, University Hospital Heidelberg, Schlierbacher Landstraße 200a, Heidelberg D-69118, Germany.
| | - Wolfram Stiller
- Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, Heidelberg D-69120, Germany.
| | - Iris Burkholder
- Department of Nursing and Health, University of Applied Sciences oft he Saarland, Goebenstrasse 40, Saarbruecken D-66117, Germany.
| | - Hans-Ulrich Kauczor
- Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, Heidelberg D-69120, Germany.
| | - Volker Ewerbeck
- Orthopedic and Trauma Surgery, University Hospital Heidelberg, Schlierbacher Landstraße 200a, Heidelberg D-69118, Germany.
| | - Marc-André Weber
- Diagnostic and Interventional Radiology, University Hospital Heidelberg, Im Neuenheimer Feld 110, Heidelberg D-69120, Germany.
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Elshiekh E, Suliman II, Habbani F. Performance evaluation of two computed radiography systems and patient dose in pelvic examination. RADIATION PROTECTION DOSIMETRY 2015; 165:392-396. [PMID: 25836691 DOI: 10.1093/rpd/ncv125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This study was carried out to evaluate the performance of two computed radiography (CR) units. These evaluations became necessary following the introduction of CR systems in Sudan. Evaluation of the CR systems was performed using physical image quality parameters: signal transfer property, modulation transfer function, normalised noise power spectrum, detective quantum efficiency and the subjective contrast detail detectability. Patient dose was measured in terms of entrance surface air kerma estimated from tube output and exposure factors for 100 patients who had undergone pelvic X-ray examinations. Fuji computed radiography velocity system with columnar screen dose results was much lower than those using CR975 system with granular screen. Patient doses delivered by both systems were within the international diagnostic reference levels.
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Affiliation(s)
- E Elshiekh
- Radiation Safety Institute, Sudan Atomic Energy Commission, P.O. Box. 3001, Khartoum, Sudan
| | - I I Suliman
- Radiation Safety Institute, Sudan Atomic Energy Commission, P.O. Box. 3001, Khartoum, Sudan Department of Radiology & Molecular Imaging, Medical Physics Section; College of Medicine and Health Sciences, Sultan Qaboos University, Postcode 123, P.O. Box 35, Al-Khod, Oman
| | - F Habbani
- Department of Physics, Faculty of Science, University of Khartoum, P.O. Box 321, Khartoum, Sudan
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Kloth JK, Rickert M, Gotterbarm T, Stiller W, Burkholder I, Kauczor HU, Ewerbeck V, Weber MA. Pelvic X-ray examinations in follow-up of hip arthroplasty or femoral osteosynthesis – Dose reduction and quality criteria. Eur J Radiol 2015; 84:915-20. [DOI: 10.1016/j.ejrad.2015.02.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 02/03/2015] [Indexed: 11/29/2022]
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Quality-controlled dose reduction of full-leg radiography in patients with knee malalignment. Skeletal Radiol 2015; 44:423-9. [PMID: 25476156 DOI: 10.1007/s00256-014-2004-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 08/13/2014] [Accepted: 09/02/2014] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Digital plain radiographs of the full leg are frequently performed examinations of children and young adults. Thus, the objective of this work was to reduce the radiation exposure dependent on specific indications, and to determine objective quality-control criteria to ensure accurate assessment. MATERIALS AND METHODS Institutional review board approval and informed consent of all participants were obtained. In this prospective, randomized controlled, blinded, two-armed single-center study, 288 evaluable patients underwent plain radiography of the full leg with standard and reduced doses. The evaluation of the plain radiographs was conducted using the following criteria: mechanical axis, leg length, and maturation of the epiphyseal plate. Two blinded radiologists evaluated these criteria using a score ranging from 1 (definitely assessable) to 4 (not assessable). If a single criterion had been evaluated with a score of 3 or more points or all criteria with 2 points, the radiograph was scored as "not assessable". The study was designed as a non-inferiority trial. RESULTS Eleven (3.8%) examined X-rays were scored as not assessable. The rate of non-assessable radiographs with 33% reduced dose was significantly not inferior to the rate of non-assessable radiographs with standard dose. The evaluation of the quality criteria was dose independent. CONCLUSIONS Full-leg plain radiography in patients with knee malalignment can be performed at 33% reduced dose without loss of relevant diagnostic information.
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Dual-Energy MDCT in Hypervascular Liver Tumors: Effect of Body Size on Selection of the Optimal Monochromatic Energy Level. AJR Am J Roentgenol 2014; 203:1257-64. [DOI: 10.2214/ajr.13.12229] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Liu H, Chakrabarti K, Kaczmarek RV, Benevides L, Gu S, Kyprianou IS. Evaluation of clinical full field digital mammography with the task specific system-model-based Fourier Hotelling observer (SMFHO) SNR. Med Phys 2014; 41:051907. [PMID: 24784386 DOI: 10.1118/1.4870377] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE The purpose of this work is to evaluate the performance of the image acquisition chain of clinical full field digital mammography (FFDM) systems by quantifying their image quality, and how well the desired information is captured by the images. METHODS The authors present a practical methodology to evaluate FFDM using the task specific system-model-based Fourier Hotelling observer (SMFHO) signal to noise ratio (SNR), which evaluates the signal and noise transfer characteristics of FFDM systems in the presence of a uniform polymethyl methacrylate phantom that models the attenuation of a 6 cm thick 20/80 breast (20% glandular/80% adipose). The authors model the system performance using the generalized modulation transfer function, which accounts for scatter blur and focal spot unsharpness, and the generalized noise power spectrum, both estimated with the phantom placed in the field of view. Using the system model, the authors were able to estimate system detectability for a series of simulated disk signals with various diameters and thicknesses, quantified by a SMFHO SNR map. Contrast-detail (CD) curves were generated from the SNR map and adjusted using an estimate of the human observer efficiency, without performing time-consuming human reader studies. Using the SMFHO method the authors compared two FFDM systems, the GE Senographe DS and Hologic Selenia FFDM systems, which use indirect and direct detectors, respectively. RESULTS Even though the two FFDM systems have different resolutions, noise properties, detector technologies, and antiscatter grids, the authors found no significant difference between them in terms of detectability for a given signal detection task. The authors also compared the performance between the two image acquisition modes (fine view and standard) of the GE Senographe DS system, and concluded that there is no significant difference when evaluated by the SMFHO. The estimated human observer efficiency was 30 ± 5% when compared to the SMFHO. The results showed good agreement when compared to other model observers as well as previously published human observer data. CONCLUSIONS This method generates CD curves from the SMFHO SNR that can be used as figures of merit for evaluating the image acquisition performance of clinical FFDM systems. It provides a way of creating an empirical model of the FFDM system that accounts for patient scatter, focal spot unsharpness, and detector blur. With the use of simulated signals, this method can predict system performance for a signal known exactly/background known exactly detection task with a limited number of images, therefore, it can be readily applied in a clinical environment.
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Affiliation(s)
- Haimo Liu
- FDA Center for Devices and Radiological Health, Silver Spring, Maryland 20993-0002 and Department of Bioengineering, University of Maryland, College Park, Maryland 20742
| | - Kish Chakrabarti
- US FDA Center for Devices and Radiological Health, Silver Spring, Maryland 20993-0002
| | - Richard V Kaczmarek
- US FDA Center for Devices and Radiological Health, Silver Spring, Maryland 20993-0002
| | - Luis Benevides
- Radiological Controls, Naval Sea Systems Command, Washington, DC 20376
| | - Songxiang Gu
- US FDA Center for Devices and Radiological Health, Silver Spring, Maryland 20993-0002
| | - Iacovos S Kyprianou
- US FDA Center for Devices and Radiological Health, Silver Spring, Maryland 20993-0002 and Department of Bioengineering, University of Maryland, College Park, Maryland 20742
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Salvagnini E, Bosmans H, Struelens L, Marshall NW. Effective detective quantum efficiency for two mammography systems: measurement and comparison against established metrics. Med Phys 2014; 40:101916. [PMID: 24089918 DOI: 10.1118/1.4820362] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
PURPOSE The aim of this paper was to illustrate the value of the new metric effective detective quantum efficiency (eDQE) in relation to more established measures in the optimization process of two digital mammography systems. The following metrics were included for comparison against eDQE: detective quantum efficiency (DQE) of the detector, signal difference to noise ratio (SdNR), and detectability index (d') calculated using a standard nonprewhitened observer with eye filter. METHODS The two systems investigated were the Siemens MAMMOMAT Inspiration and the Hologic Selenia Dimensions. The presampling modulation transfer function (MTF) required for the eDQE was measured using two geometries: a geometry containing scattered radiation and a low scatter geometry. The eDQE, SdNR, and d' were measured for poly(methyl methacrylate) (PMMA) thicknesses of 20, 40, 60, and 70 mm, with and without the antiscatter grid and for a selection of clinically relevant target/filter (T/F) combinations. Figures of merit (FOMs) were then formed from SdNR and d' using the mean glandular dose as the factor to express detriment. Detector DQE was measured at energies covering the range of typical clinically used spectra. RESULTS The MTF measured in the presence of scattered radiation showed a large drop at low spatial frequency compared to the low scatter method and led to a corresponding reduction in eDQE. The eDQE for the Siemens system at 1 mm(-1) ranged between 0.15 and 0.27, depending on T/F and grid setting. For the Hologic system, eDQE at 1 mm(-1) varied from 0.15 to 0.32, again depending on T/F and grid setting. The eDQE results for both systems showed that the grid increased the system efficiency for PMMA thicknesses of 40 mm and above but showed only small sensitivity to T/F setting. While results of the SdNR and d' based FOMs confirmed the eDQE grid position results, they were also more specific in terms of T/F selection. For the Siemens system at 20 mm PMMA, the FOMs indicated Mo/Mo (grid out) as optimal while W/Rh (grid in) was the optimal configuration at 40, 60, and 70 mm PMMA. For the Hologic, the FOMs pointed to W/Rh (grid in) at 20 and 40 mm of PMMA while W/Ag (grid in) gave the highest FOM at 60 and 70 mm PMMA. Finally, DQE at 1 mm(-1) averaged for the four beam qualities studied was 0.44 ± 0.02 and 0.55 ± 0.03 for the Siemens and Hologic detectors, respectively, indicating only a small influence of energy on detector DQE. CONCLUSIONS Both the DQE and eDQE data showed only a small sensitivity to T/F setting for these two systems. The eDQE showed clear preferences in terms of scatter reduction, being highest for the grid-in geometry for PMMA thicknesses of 40 mm and above. The SdNR and d' based figures of merit, which contain additional weighting for contrast and dose, pointed to specific T/F settings for both systems.
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Affiliation(s)
- Elena Salvagnini
- UZ Gasthuisberg, Medical Imaging Research Center and Department of Radiology, Herestraat 49, B-3000 Leuven, Belgium and SCK●CEN, Boeretang 200, B-2400 Mol, Belgium
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Moore CS, Wood TJ, Avery G, Balcam S, Needler L, Beavis AW, Saunderson JR. An investigation of automatic exposure control calibration for chest imaging with a computed radiography system. Phys Med Biol 2014; 59:2307-24. [DOI: 10.1088/0031-9155/59/9/2307] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Zhou Z, Zhu Q, Zhao H, Zhang L, Ma W, Gao F. Techniques to Improve the Accuracy of Presampling MTF Measurement in Digital X-ray Imaging Based on Constrained Spline Regression. IEEE Trans Biomed Eng 2014; 61:1339-49. [DOI: 10.1109/tbme.2014.2304955] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Park HS, Kim YS, Park OS, Kim ST, Jeon CW, Kim HJ. Effective DQE (eDQE) and dose to optimize radiographic technical parameters: a survey of pediatric chest X-ray examinations in Korea. Radiol Med 2013; 119:231-9. [DOI: 10.1007/s11547-013-0337-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2012] [Accepted: 03/13/2012] [Indexed: 01/17/2023]
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Boyce SJ, Choudhury KR, Samei E. Effective DQE (eDQE) for monoscopic and stereoscopic chest radiography imaging systems with the incorporation of anatomical noise. Med Phys 2013; 40:091916. [PMID: 24007167 DOI: 10.1118/1.4818060] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
PURPOSE Stereoscopic chest biplane correlation imaging (stereo∕BCI) has been proposed as an alternative modality to single view chest x-ray (CXR). The metrics effective modulation transfer function (eMTF), effective normalized noise power spectrum (eNNPS), and effective detective quantum efficiency (eDQE) have been proposed as clinically relevant metrics for assessing clinical system performance taking into consideration the magnification and scatter effects. This study compared the metrics eMTF, eNNPS, eDQE, and detectability index for stereo∕BCI and single view CXR under isodose conditions at two magnifications for two anthropomorphic phantoms of differing sizes. METHODS Measurements for the eMTF were taken for two phantom sizes with an opaque edge test device using established techniques. The eNNPS was measured at two isodose conditions for two phantoms using established techniques. The scatter was measured for two phantoms using an established beam stop method. All measurements were also taken at two different magnifications with two phantoms. A geometrical phantom was used for comparison with prior results for CXR although the results for an anatomy free phantom are not expected to vary for BCI. RESULTS Stereo∕BCI resulted in improved metrics compared to single view CXR. Results indicated that magnification can potentially improve the detection performance primarily due to the air gap which reduced scatter by ∼20%. For both phantoms, at isodose, eDQE(0) for stereo∕BCI was ∼100 times higher than that for CXR. Magnification at isodose improved eDQE(0) by ∼10 times for stereo∕BCI. Increasing the dose did not improve eDQE. The detectability index for stereo∕BCI was ∼100 times better than single view CXR for all conditions. The detectability index was also not improved with increased dose. CONCLUSIONS The findings indicate that stereo∕BCI with magnification may improve detectability of subtle lung nodules compared to single view CXR. Results were improved with magnification for the smaller phantom but not for the larger phantom. The effective DQE and the detectability index did not improve with increasing dose.
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Affiliation(s)
- Sarah J Boyce
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705, USA.
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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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Moore CS, Wood TJ, Beavis AW, Saunderson JR. Correlation of the clinical and physical image quality in chest radiography for average adults with a computed radiography imaging system. Br J Radiol 2013; 86:20130077. [PMID: 23568362 DOI: 10.1259/bjr.20130077] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE The purpose of this study was to examine the correlation between the quality of visually graded patient (clinical) chest images and a quantitative assessment of chest phantom (physical) images acquired with a computed radiography (CR) imaging system. METHODS The results of a previously published study, in which four experienced image evaluators graded computer-simulated postero-anterior chest images using a visual grading analysis scoring (VGAS) scheme, were used for the clinical image quality measurement. Contrast-to-noise ratio (CNR) and effective dose efficiency (eDE) were used as physical image quality metrics measured in a uniform chest phantom. Although optimal values of these physical metrics for chest radiography were not derived in this work, their correlation with VGAS in images acquired without an antiscatter grid across the diagnostic range of X-ray tube voltages was determined using Pearson's correlation coefficient. RESULTS Clinical and physical image quality metrics increased with decreasing tube voltage. Statistically significant correlations between VGAS and CNR (R=0.87, p<0.033) and eDE (R=0.77, p<0.008) were observed. CONCLUSION Medical physics experts may use the physical image quality metrics described here in quality assurance programmes and optimisation studies with a degree of confidence that they reflect the clinical image quality in chest CR images acquired without an antiscatter grid. ADVANCES IN KNOWLEDGE A statistically significant correlation has been found between the clinical and physical image quality in CR chest imaging. The results support the value of using CNR and eDE in the evaluation of quality in clinical thorax radiography.
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Affiliation(s)
- C S Moore
- Radiation Physics Department, Queen's Centre for Oncology and Haematology, Castle Hill Hospital, Hull and East Yorkshire Hospitals, Hull, UK.
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Park HS, Oh Y, Kim ST, Kim HJ. Effects of breast thickness and lesion location on resolution in digital magnification mammography. Clin Imaging 2012; 36:255-62. [PMID: 22726961 DOI: 10.1016/j.clinimag.2011.11.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 09/18/2011] [Accepted: 11/10/2011] [Indexed: 10/28/2022]
Abstract
This study aimed to examine the resolution effects of breast thickness and lesion location in magnification mammography by evaluating generalized modulation transfer function (GMTF) including the effect of focal spot, effective pixel size, and the scatter. Polymethyl methacrylate (PMMA) thicknesses ranging from 10 to 40 mm were placed on a standard supporting platform that was positioned to achieve magnification factors ranging from 1.2 to 2.0. As the magnification increased, the focal spot MTF degraded, while the detector MTF improved. The GMTF depended on the trade-off between the focal spot size and effective pixel size. Breast thickness and lesion location had little effect on the resolution at high frequencies. The resolution of small focal spot did improve slightly with increasing PMMA thickness for magnification factors less than 1.8. In contrast, system resolution decreased with increasing PMMA thickness for magnification factors greater than 1.8 since focal spot blur begins to dominate spatial resolution. In particular, breast thickness had a large effect on the resolution at lower frequencies. A low-frequency drop effect increased with increasing PMMA thickness because of the increase in scatter fraction. Hence, the effect of compressed breast thickness should be considered for the standard magnification factor of 1.8 that is most commonly used in clinical practice. Our results should provide insights for determining optimum magnification in clinical application of digital mammography, and our approaches can be extended to a wide diversity of radiological imaging systems.
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Affiliation(s)
- Hye-Suk Park
- Department of Radiological Science and Research Institute of Health Science, Yonsei University, Wonju, South Korea
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Bertolini M, Nitrosi A, Rivetti S, Lanconelli N, Pattacini P, Ginocchi V, Iori M. A comparison of digital radiography systems in terms of effective detective quantum efficiency. Med Phys 2012; 39:2617-27. [DOI: 10.1118/1.4704500] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Poletti J, McLean D. Monte Carlo simulation of the effect of focal spot size on contrast-detail detectability. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2011; 35:41-8. [DOI: 10.1007/s13246-011-0118-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Accepted: 11/23/2011] [Indexed: 11/27/2022]
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Samei E, Ranger NT, Dobbins JT, Ravin CE. Effective dose efficiency: an application-specific metric of quality and dose for digital radiography. Phys Med Biol 2011; 56:5099-118. [DOI: 10.1088/0031-9155/56/16/002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Abstract
Current day digital mammography acquisition units have already been shown to be equal or better than screen film systems for the detection and classification of breast lesions. The optimal multimodality breast imaging diagnostic workstations and connectivity to existing picture and archiving communication systems and information systems is still a work in progress, but with more and more facilities transitioning to digital imaging it is only a matter of time until these hurdles are overcome.
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Affiliation(s)
- Margarita L Zuley
- Magee-Womens Hospital of UPMC, Breast Imaging Department, 300 Halket Street, 3rd Floor, Pittsburgh, PA 15213, USA.
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Marshall NW. An examination of automatic exposure control regimes for two digital radiography systems. Phys Med Biol 2009; 54:4645-70. [DOI: 10.1088/0031-9155/54/15/002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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