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Nobukazu Tanaka Last modified date:2024.02.08

Undergraduate School

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Academic Degree
Field of Specialization
Medical imaging technology, Radiological technology
Research Interests
  • Investigation on imaging technology for ultrasound diagnostic system
    keyword : ultrasonography, elastography, breast image, imaging technique, image evaluation
  • Investigation on evaluation for image quality and exposure dose for digital radiographic system
    keyword : flat panel detector, computed radiography, image quality evaluation, exposure dose, detectability
  • Investigation on evaluation of characteristics of liquid crystal display
    keyword : liquid crystal display, image quality evaluation, luminance, gradation characteristic, lighting environment
Academic Activities
1. Contributors: Nobukazu Tanaka, Junji Morishita. Editor: Paolo Russo, Handbook of X-ray Imaging: Physics and Technology, CRC Press, Taylor & Francis Group, Chapter 12: Computed Radiography. p.219-p.238, (Publication date, eBook: December 14, 2017, Hardback: January 5, 2018), 2017.12, The last paragraph of summary.
This chapter mainly introduces the characteristics of the CR system with a focus on image quality and detectability. Newer technologies, such as needle-based PSP plates, dual-side reading systems, and line-scanning technology, result in higher image quality. The newer CR system provides excellent diagnostic capabilities coupled with advanced image-processing technology.
1. Nobukazu Tanaka, Yongsu Yoon, Effect of anti‑scatter grids on the image improvement factor in digital radiography for various phantom thicknesses and irradiation fields, Physical and Engineering Sciences in Medicine, 46, 3, 1187-1192, 2023.09.
2. Nobukazu Tanaka, Hiroyuki Kuroyanagi, Combination system in advanced image processing for improving image contrast and a conventional row-ratio grid for an indirect flat-panel detector system: An experimental study, Physica Medica (European Journal of Medical Physics), 74, 40-46, 2020.06, Conventional grids with high grid ratios are not ideal for use in bedside radiography because of the difficulty in maintaining the required alignment. To address this issue, the potential usefulness of a combination system that employs removal processing software for scattered radiation and a conventional grid with a low grid ratio (3:1) for an indirect-conversion-type flat-panel detector system was evaluated by measuring image quality and observer performance. The hypothetical grid ratios for the software were 2:1, 3:1, 6:1, 8:1, and 10:1. The scatter fraction of the combination system was lower than that of the software alone. Significant improvement was observed in the effect of scattered radiation removal up to a hypothetical software grid ratio of 6:1. However, the Wiener spectrum increased (radiographic noise degraded) with an increase in the hypothetical grid ratio. The contrast ratios of the combination system were improved compared to those of the software alone for anthropomorphic chest radiographs. An observer test was also conducted using the contrast-detail phantom. The combination system indicated higher low-contrast detectability compared to the software alone, although there were no statistical differences between the hypothetical grid ratios of 6:1, 8:1, and 10:1 in all combinations of the software alone and the combination system. We concluded that a combination system with software that uses a hypothetical grid ratio of 6:1 or more and a 3:1 conventional grid would be more useful for reducing the scattered radiation component compared to the software alone with a hypothetical higher grid ratio for thicker objects..
3. Nobukazu Tanaka, Junji Morishita, Norisato Tsuda, Masafumi Ohki, Effect of readout direction in the edge profile on the modulation transfer function of computed radiographic systems by use of the edge method, Radiological Physics and Technology, 6, 2, 474-479, 2013.07.
4. Nobukazu Tanaka, Yuki Yano, Hidetake Yabuuchi, Tsutomu Akasaka, Masayuki Sasaki, Masafumi Ohki, Junji Morishita, Basic imaging properties of an indirect flat-panel detector system employing irradiation side sampling (ISS) technology for chest radiography: comparison with a computed radiographic system, Radiological Physics and Technology, 6, 1, 162-169, 2013.01.
5. Nobukazu Tanaka, Kentaro Naka, Aya Saito, Junji Morishita, Fukai Toyofuku, Masafumi Ohki, Yoshiharu Higashida, Investigation of optimum anti-scatter grid selection for digital radiography: physical imaging properties and detectability of low-contrast signals, Radiological Physics and Technology, 6, 1, 54-60, 2013.01.
6. Nobukazu Tanaka, Kentaro Naka, Hiroko Fukushima, Junji Morishita, Fukai Toyofuku, Masafumi Ohki, Yoshiharu Higashida, Digital magnification mammography with matched incident exposure: physical imaging properties and detectability of simulated microcalcifications, Radiological Physics and Technology, 4, 2, 156-163, 2011.07.
1. Nobukazu Tanaka, Nozomi Tateishi, Saki Mitarai, Evaluation of Chromaticity of Color Images in Breast Ultrasound Elastography: Effects of Ambient Lighting and LCD settings, 2023 Korean Society of Radiological Science Conference, 2023.06.
2. Nobukazu Tanaka, Nariaki Tabata, Takafumi Ohfuji, Nami Imoto, Toyoyuki Kato, Tadamitsu Ideguchi, Evaluation of Emphasis of Noise Suppression Processing Technology Using Structural Similarity Index(座長推薦優秀研究発表), The 1st International Conference on Radiological Physics and Technology (ICRPT), 2022.04.
3. Nobukazu Tanaka, Tadamitsu Ideguchi, Relationship Between Exposure Index and Detector Performance for an Indirect-Conversion-Type Flat-Panel Detector System(Outstanding Paper Award), Korean Society of Radiological Science Conference (KSRSC) 2021, 2021.05, Introduction: The exposure index (EI) was defined by the International Electrotechnical Commission (IEC) to unify the sensitivity index of each manufacturer for general radiography into the dose index. Recently, some digital radiography systems have been reported to display the EI value on the console immediately after exposure. The aim of this study was to investigate the relationship between the exposure index (EI) value and detector performance for an indirect-conversion-type flat-panel detector (indirect-FPD) system.
Materials and Methods: We used an indirect-FPD system (CALNEO Smart C47, FUJIFILM Medical Co., Ltd.). An X-ray beam quality of RQA5 as noted by IEC report 61267 was employed in this study. Regarding the EI value, we confirmed the value that was automatically displayed on the console after exposure. The image quality and X-ray absorption efficiency of the FPD system were evaluated by measuring the noise equivalent quanta (NEQ) and detective quantum efficiency (DQE), respectively. The relationships between the displayed EI and NEQ and DQE were compared, respectively.
Results: The displayed EI value increased proportionally with increases in the exposure dose. The NEQ, like the EI value, increased as the exposure dose increased. Meanwhile, the DQE decreased above a certain exposure dose due to the balance between radiographic noise improvement and increases in the exposure dose. Therefore, the relationship between the EI and DQE was not proportional.
Conclusion: We indicated that managing the displayed EI value may easily reveal the image quality and X-ray absorption efficiency..
4. Nobukazu Tanaka, Toyoyuki Kato, Akiko Hattori, Junji Morishita, Imaging Properties of an Indirect-conversion-type Flat-panel Detector System with a High-resolution Type(座長推薦優秀研究発表), 日本放射線技術学会第75回総会学術大会, 2019.04.
5. Nobukazu Tanaka, Noriko Mizoguchi, Saki Yamaguchi, Akiko Hattori, Hidetake Yabuuchi, Junji Morishita, Toyoyuki Kato, Yuki Yano, Kiyo Iwakiri, Chihiro Matsuo, Yoshiyuki Umezu, Yasuhiko Nakamura, Imaging properties of a new direct conversion type flat panel detector system employing optical switching technology, Radiological Society of North America (RSNA) 98th Scientific Assembly and Annual Meeting, 2012.11.
Membership in Academic Society
  • Japanese Society of Radiological Technology
  • Japan Society of Medical Physics
  • Medical Imaging and Information Sciences
  • European Society of Radiology