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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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Han B, Park M, Kim K, Lee Y. Characterization of Flexible Amorphous Silicon Thin-Film Transistor-Based Detectors with Positive-Intrinsic-Negative Diode in Radiography. Diagnostics (Basel) 2022; 12:diagnostics12092103. [PMID: 36140503 PMCID: PMC9497934 DOI: 10.3390/diagnostics12092103] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 08/26/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
Low-dose exposure and work convenience are required for mobile X-ray systems during the COVID-19 pandemic. We investigated a novel X-ray detector (FXRD-4343FAW, VIEWORKS, Anyang, Korea) composed of a thin-film transistor based on amorphous silicon with a flexible plastic substrate. This detector is composed of a thallium-doped cesium iodide scintillator with a pixel size of 99 μm, pixel matrix of 4316 × 4316, and weight of 2.95 kg. The proposed detector has the advantages of high-noise characteristics and low weight, which provide patients and workers with an advantage in terms of the dose and work efficiency, respectively. We performed a quantitative evaluation and an experiment to demonstrate its viability. The modulation transfer function, noise power spectrum, and detective quantum efficiency were identified using the proposed and comparative detectors, according to the International Electrotechnical Commission protocol. Additionally, the contrast-to-noise ratio and coefficient of variation were investigated using a human-like phantom. Our results indicate that the proposed detector efficiently increases the image performance in terms of noise characteristics. The detailed performance evaluation demonstrated that the outcomes of the use of the proposed detector confirmed the viability of mobile X-ray devices that require low doses. Consequently, the novel FXRD-4343FAW X-ray detector is expected to improve the image quality and work convenience in extended radiography.
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Affiliation(s)
- Bongju Han
- Quality Assurance Team, Business Division, Vieworks, 41-3, Burim-ro 170beon-gil, Dongan-gu, Anyang-si 14055, Korea
| | - Minji Park
- Department of Radiological Science, College of Health Science, Gachon University, 191, Hambakmoe-ro, Yeonsu-gu, Incheon 21936, Korea
- Department of Health Science, General Graduate School of Gachon University, 191, Hambakmoe-ro, Yeonsu-gu, Incheon 21936, Korea
| | - Kyuseok Kim
- Department of Integrative Medicine, Major in Digital Healthcare, Yonsei University College of Medicine, Unju-ro, Gangman-gu, Seoul 06229, Korea
- Correspondence: (K.K.); (Y.L.); Tel.: +82-02-2019-5447 (K.K.); +82-32-820-4362 (Y.L.)
| | - Youngjin Lee
- Department of Radiological Science, College of Health Science, Gachon University, 191, Hambakmoe-ro, Yeonsu-gu, Incheon 21936, Korea
- Correspondence: (K.K.); (Y.L.); Tel.: +82-02-2019-5447 (K.K.); +82-32-820-4362 (Y.L.)
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Takarabe S, Kuramoto T, Shibayama Y, Yamasaki Y, Kitamura Y, Yoshikawa H, Kato T. Is the image quality of conventional chest radiography obtained from a two-layer flat panel detector affected by the internal structure of the detector? Phys Med 2022; 95:176-181. [PMID: 35219067 DOI: 10.1016/j.ejmp.2022.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/26/2022] [Accepted: 02/01/2022] [Indexed: 11/19/2022] Open
Abstract
PURPOSE Recently developed and commercialized dual-layer flat panel detectors (DL-FPDs) with two indirect scintillators are capable of acquiring dual-energy X-ray images. However, in clinical practice, they are utilized to perform conventional radiography using diagnostic X-rays with a wide energy spectrum. The two layers of the DL-FPD may affect the obtained image quality, even when only using one layer for conventional image acquisition, and these effects are yet to be substantiated. Therefore, in this study, we quantitatively evaluated the image quality of a conventional chest radiography using DL-FPD and visually verified the characteristics of the chest anthropomorphic phantom images. METHODS The physical characteristics of the system were evaluated using the pre-sampled modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE), for beam quality RQA 7 and RQA 9. In addition, the subjective visibility of the anthropomorphic chest phantom and simple objects images were compared with those of a conventional single-layer flat-panel detector (SL-FPD). RESULTS No significant differences were found in the MTF between the SL-FPD and DL-FPD images. In addition, a higher DQE was observed at some exposure doses and in the high spatial frequency regions wherein NNPSs were lower for DL-FPD than for SL-FPD. Furthermore, no significant differences were found in the subjective visibility of the chest phantoms in each system. CONCLUSIONS We concluded that the image quality of the conventional radiography acquired with DL-FPD is comparable to or better than that of the SL-FPD.
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Affiliation(s)
- Shinya Takarabe
- Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan; Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Taku Kuramoto
- Department of Radiological Technology, Faculty of Health Sciences, Kobe Tokiwa University, 2-6-2 Otanicho, Nagata-ku, Kobe 653-0838, Japan.
| | - Yusuke Shibayama
- Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Yuzo Yamasaki
- Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Yoshiyuki Kitamura
- Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Hideki Yoshikawa
- Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Toyoyuki Kato
- Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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A single phantom, a single statistical method for low-contrast detectability assessment. Phys Med 2021; 91:28-42. [PMID: 34710789 DOI: 10.1016/j.ejmp.2021.10.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 10/01/2021] [Accepted: 10/05/2021] [Indexed: 11/22/2022] Open
Abstract
PURPOSE The assessment of low-contrast-details is a part of the quality control (QC) program in digital radiology. It generally consists of evaluating the threshold contrast (Cth) detectability details for different-sized inserts, appropriately located in dedicated QC test tools. This work aims to propose a simplified method, based on a statistical model approach for threshold contrast estimation, suitable for different modalities in digital radiology. METHODS A home-madelow-contrast phantom, made of a central aluminium insert with a step-wedge, was assembled and tested. The reliability and robustness of the method were investigated for Mammography, Digital Radiography, Fluoroscopy and Angiography. Imageswere analysed using our dedicated software developed on Matlab®. TheCth is expressed in the same unit (mmAl) for all studied modalities. RESULTS This method allows the collection of Cthinformation from different modalities and equipment by different vendors, and it could be used to define typical values. Results are summarized in detail. For 0.5 diameter detail, Cthresults are in the range of: 0.018-0.023 mmAl for 2D mammography and 0.26-0.34 mmAl DR images. For angiographic images, for 2.5 mm diameter detail, the Cths median values are 0.55, 0.4, 0.06, 0.12 mmAl for low dose fluoroscopy, coronary fluorography, cerebral and abdominal DSA, respectively. CONCLUSIONS The statistical method proposed in this study gives a simple approach for Low-Contrast-Details assessment, and the typical values proposed can be implemented in a QA program for digital radiology modalities.
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Kawashima H, Ichikawa K, Kunitomo H. [Relationship between Radiation Quality and Image Quality in Digital Chest Radiography: Validation Study Using Human Soft Tissue-equivalent Phantom]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2021; 77:255-262. [PMID: 33746173 DOI: 10.6009/jjrt.2021_jsrt_77.3.255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To evaluate image quality for chest radiography at different radiation qualities, using phantoms with scatter fractions similar to those of lungs. METHODS Two base phantoms with 10 and 4 cm thicknesses, respectively, made of a soft tissue-equivalent material, were used to mimic the X-ray attenuation of the human lung. Two plates with soft tissue- and bone-equivalent materials, respectively, were placed on the base phantom as contrast objects. The image data were obtained with the same entrance surface dose in each radiation quality. Six radiation qualities generated using 120 and 90 kV, and additional copper filters with thicknesses 0, 0.1, and 0.2 mm were selected. The signal-difference-to-noise ratio (SdNR) and a contrast ratio of the soft tissue to the bone were measured for the six radiation qualities. RESULTS The thicker the additional filter, the better the SdNR at both tube voltages. The SdNR values were not significantly different between 120 and 90 kV for the same filter thickness. The contrast ratio was higher at 120 than at 90 kV by approximately 8%. CONCLUSIONS Because of the advantage of the contrast ratio and the highest SdNR, the radiation quality with 120 kV and 0.2-mm copper filtration was the best. It was indicated that the conventional tube voltage of 120 kV remains to be better than the lower tube voltage of 90 kV.
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Affiliation(s)
- Hiroki Kawashima
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University
| | - Katsuhiro Ichikawa
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University
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González-López A, Campos-Morcillo PA, Vera-Sánchez JA, Ruiz-Morales C. Performance of a new star-bar phantom designed for MTF calculations in x-ray imaging systems. Med Phys 2020; 47:4949-4955. [PMID: 32750161 DOI: 10.1002/mp.14426] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/11/2020] [Accepted: 07/24/2020] [Indexed: 01/23/2023] Open
Abstract
PURPOSE A new phantom, designed and manufactured for modulation transfer function (MTF) calculations is presented in this work. The phantom has a star-bar pattern and is manufactured in stainless steel. Modulation transfer function determinations are carried out with the new phantom and with an edge phantom to compare their performance and to compare them with previous theoretical predictions. METHODS The phantoms are imaged in an x-ray imaging system using different beam qualities and different entrance air KERMA. Methods, previously developed for synthetic images and simulations, are adapted to real measurements, solving practical implementation issues. RESULTS In the case of the star-bar, in order to obtain optimal MTF determinations it is necessary to accurately determine the center of the pattern. Also, to avoid underestimates in MTF calculations, the length in pixels of each of the scanning circumferences must be an integer multiple of the number of cycles in the pattern. Both methods, star-bar and edge, give similar mean values of the MTF in all cases analyzed. Also, the dependence with frequency of the experimental MTF standard deviation (SD) agrees with the theoretical expressions presented in previous works. In this regard, the precision is better for the star-bar method than for the edge and differences in precision between both methods are higher for the lowest beam quality. CONCLUSIONS The star-bar phantom can be used for MTF determinations with the advantage of having an improved precision. However, precision is reduced when the radiation quality increases. This fact suggests that, for the highest beam qualities, materials with an attenuation coefficient greater than that of steel should be used to manufacture the phantom.
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Affiliation(s)
- Antonio González-López
- Hospital Universitario Virgen de la Arrixaca, ctra. Madrid-Cartagena, El Palmar, Murcia, 30120, Spain
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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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Howansky A, Mishchenko A, Lubinsky AR, Zhao W. Comparison of CsI:Tl and Gd 2 O 2 S:Tb indirect flat panel detector x-ray imaging performance in front- and back-irradiation geometries. Med Phys 2019; 46:4857-4868. [PMID: 31461532 PMCID: PMC6842040 DOI: 10.1002/mp.13791] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/26/2019] [Accepted: 08/16/2019] [Indexed: 01/30/2023] Open
Abstract
PURPOSE The detective quantum efficiency (DQE) of indirect flat panel detectors (I-FPDs) is limited at higher x-ray energies (e.g., 100-140 kVp) by low absorption in their scintillating x-ray conversion layer. While increasing the thickness of the scintillator can improve its x-ray absorption efficiency, this approach is potentially limited by reduced spatial resolution and increased noise due to depth dependence in the scintillator's response to x rays. One strategy proposed to mitigate these deleterious effects is to irradiate the scintillator through the pixel sensor in a "back-irradiation" geometry. This work directly evaluates the impact of irradiation geometry on the inherent imaging performance of I-FPDs composed with columnar CsI:Tl and powder Gd2 O2 S:Tb (GOS) scintillators. METHODS A "bidirectional" FPD was constructed which allows scintillator samples to be interchangeably coupled with the detector's active matrix to compose an I-FPD. Radio-translucent windows in the detector's housing permit imaging in both "front-irradiation" (FI) and "back-irradiation" (BI) geometries. This test device was used to evaluate the impact of irradiation geometry on the x-ray sensitivity, modulation transfer function (MTF), noise power spectrum (NPS), and DQE of four I-FPDs composed using columnar CsI:Tl scintillators of varying thickness (600-1000 µm) and optical backing, and a Fast Back GOS screen. All experiments used an RQA9 x-ray beam. RESULTS Each I-FPD's x-ray sensitivity, MTF, and DQE was greater or equal in BI geometry than in FI. The I-FPD composed with CsI:Tl (1 mm) and an optically absorptive backing had the largest variation in sensitivity (17%) between FI and BI geometries. The detector composed with GOS had the largest improvement in limiting resolution (31%). Irradiation geometry had little impact on MTF(f) and DQE(f) measurements near zero frequency, however, the difference between FI and BI measurements generally increased with spatial frequency. The CsI:Tl scintillator with optically absorptive backing (1 mm) in BI geometry had the highest spatial resolution and DQE over all frequencies. CONCLUSIONS Back irradiation may improve the inherent x-ray imaging performance of I-FPDs composed with CsI:Tl and GOS scintillators. This approach can be leveraged to improve tradeoffs between detector dose efficiency, spatial resolution and noise for higher energy x-ray imaging.
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Affiliation(s)
- Adrian Howansky
- Department of Radiology, Stony Brook University, Stony Brook, NY, 11794-8460, USA
| | | | - A R Lubinsky
- Department of Radiology, Stony Brook University, Stony Brook, NY, 11794-8460, USA
| | - Wei Zhao
- Department of Radiology, Stony Brook University, Stony Brook, NY, 11794-8460, USA
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Kawashima H, Ichikawa K, Hanaoka S, Matsubara K. Optimizing image quality using automatic exposure control based on the signal-difference-to-noise ratio: a phantom study. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2019; 42:803-810. [PMID: 31396856 DOI: 10.1007/s13246-019-00784-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 07/25/2019] [Accepted: 07/26/2019] [Indexed: 10/26/2022]
Abstract
This study proposes to adjust the sensitivity of automatic exposure control (AEC) for achieving consistent image quality over a range of subject thicknesses in abdominal radiography simulations. The relation between image quality and subject thickness was investigated using a digital radiography system with 10-, 15-, 20-, and 25-cm-thick acrylic phantom. Simple pixel signal-to-noise ratio (SNR) was measured to check the default AEC accuracy for each thickness, and image quality was evaluated using the signal-difference-to-noise ratio (SDNR) with an additional acrylic plate and bone-equivalent material. Based on the figure of merit theory, dose ratios to obtain constant image quality regardless of the subject thickness were calculated from SDNR results. The AEC setup was manually modified using this dose ratio, and visibility was examined using a CDRAD 2.0 contrast-detail analysis phantom. Moreover, the entrance surface dose (ESD) was estimated as an index of exposure dose using exposure parameters. The default AEC setup provided a constant simple pixel SNR for each subject thickness with a high accuracy. SDNRs decreased with an increase in the subject thickness. The calculated dose ratios relative to the results for 20 cm thickness were 0.424, 0.647, and 1.43 for 10, 15 and 25 cm, respectively, and a > 25% decrease in ESD was observed for smaller patients. CDRAD analysis using the modified AEC setup showed almost identical visibility for each thickness. Adjusting the sensitivity of AEC according to subject thickness can contribute toward the optimization of the exposure condition.
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Affiliation(s)
- Hiroki Kawashima
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942, Japan.
| | - Katsuhiro Ichikawa
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942, Japan
| | - Shinsuke Hanaoka
- Radiology Division, Kanazawa University Hospital, 13-1 Takara-machi, Kanazawa, 920-8641, Japan
| | - Kosuke Matsubara
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942, Japan
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Lubinsky AR, Howansky A, Zheng H, Zhao W. Back-irradiated and dual-screen sandwich detector configurations for radiography. J Med Imaging (Bellingham) 2019; 6:033501. [PMID: 31312672 DOI: 10.1117/1.jmi.6.3.033501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 06/18/2019] [Indexed: 11/14/2022] Open
Abstract
Recent advances in thin film transistor array technology have enabled the possibility of "back-irradiated" (BI) indirect active-matrix flat-panel imagers (AMFPIs), in which x-rays first expose the scintillator through the optical sensor, and "dual-screen" AMFPIs, in which two scintillating screens are sandwiched around a bidirectional active matrix. We developed a theoretical treatment of such detectors. The theory is used to investigate possible imaging performance improvements over conventional "front-irradiation" (FI) AMFPIs, where the active matrix is opposite the x-ray entrance surface. Simple expressions for the modulation transfer function, normalized noise power spectrum, Swank factor ( A s ), Lubberts function L ( f ) , and spatial frequency-dependent detective quantum efficiency DQE ( f ) are derived and used to compute these quantities for a variety of FI, BI, and dual-screen detector configurations. DQE ( f ) is used as the figure of merit for optimizing and comparing the performance of the various configurations. Large performance improvements over FI single-screen systems are found possible with BI. Further improvements are found possible with dual-screen configurations. The ratio of the thicknesses of the two screens that optimizes DQE is generally asymmetric, with the thinner screen facing the incident flux. The optimum ratio depends on the x-ray attenuation length in the screen.
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Affiliation(s)
- Anthony R Lubinsky
- Stony Brook University, Department of Radiology, Health Sciences Center, Stony Brook, New York, United States
| | - Adrian Howansky
- Stony Brook University, Department of Radiology, Health Sciences Center, Stony Brook, New York, United States
| | - Hao Zheng
- Stony Brook University, Department of Radiology, Health Sciences Center, Stony Brook, New York, United States
| | - Wei Zhao
- Stony Brook University, Department of Radiology, Health Sciences Center, Stony Brook, New York, United States
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Kim MS, Kim Y, Lim KT, Kang D, Cho G. A study on back irradiation flat panel detector with crystal silicon based x-ray CMOS image sensor. Radiat Phys Chem Oxf Engl 1993 2019. [DOI: 10.1016/j.radphyschem.2018.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Liu L, Antonuk LE, El-Mohri Y, Zhao Q, Jiang H. Theoretical investigation of the design and performance of a dual energy (kV and MV) radiotherapy imager. Med Phys 2015; 42:2072-84. [DOI: 10.1118/1.4915120] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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Donini B, Rivetti S, Lanconelli N, Bertolini M. Free software for performing physical analysis of systems for digital radiography and mammography. Med Phys 2014; 41:051903. [PMID: 24784382 DOI: 10.1118/1.4870955] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE In this paper, the authors present a free software for assisting users in achieving the physical characterization of x-ray digital systems and image quality checks. METHODS The program was developed as a plugin of a well-known public-domain suite ImageJ. The software can assist users in calculating various physical parameters such as the response curve (also termed signal transfer property), modulation transfer function (MTF), noise power spectra (NPS), and detective quantum efficiency (DQE). It also includes the computation of some image quality checks: defective pixel analysis, uniformity, dark analysis, and lag. RESULTS The software was made available in 2009 and has been used during the last couple of years by many users who gave us valuable feedback for improving its usability. It was tested for achieving the physical characterization of several clinical systems for digital radiography and mammography. Various published papers made use of the outcomes of the plugin. CONCLUSIONS This software is potentially beneficial to a variety of users: physicists working in hospitals, staff working in radiological departments, such as medical physicists, physicians, engineers. The plugin, together with a brief user manual, are freely available and can be found online (www.medphys.it/downloads.htm). With our plugin users can estimate all three most important parameters used for physical characterization (MTF, NPS, and also DQE). The plugin can run on any operating system equipped with ImageJ suite. The authors validated the software by comparing MTF and NPS curves on a common set of images with those obtained with other dedicated programs, achieving a very good agreement.
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Affiliation(s)
- Bruno Donini
- Alma Mater Studiorum, Department of Physics and Astronomy, University of Bologna, Bologna 40127, Italy
| | - Stefano Rivetti
- Fisica Medica, Ospedale di Sassuolo S.p.A., Sassuolo 41049, Italy
| | - Nico Lanconelli
- Alma Mater Studiorum, Department of Physics and Astronomy, University of Bologna, Bologna 40127, Italy
| | - Marco Bertolini
- Medical Physics Unit, Azienda Ospedaliera ASMN, Istituto di Ricovero e Cura a Carattere Scientifico, Reggio Emilia 42123, Italy
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