Curriculum Vitaes

Tomonobu Haba

  (羽場 友信)

Profile Information

Affiliation
School of Health Sciences, Fujita Health University
Degree
博士(医療技術学)(名古屋大学)

Researcher number
00810748
J-GLOBAL ID
201801015381626216
researchmap Member ID
B000307483

Papers

 29
  • Rina Nishigami, Daiki Kobayashi, Natsumi Kimoto, Takashi Asahara, Tatsuya Maeda, Tomonobu Haba, Yuki Kanazawa, Shuichiro Yamamoto, Hiroaki Hayashi
    Radiation Physics and Chemistry, 229 112460-112460, Apr, 2025  Peer-reviewed
  • Tomonobu Haba, Hiroaki Hayashi, Tsukasa Takahashi, Shota Naito, Yuichi Furukawa, Shuichiro Yamamoto, Natsumi Kimoto, Shigeki Kobayashi
    Journal of Applied Clinical Medical Physics, Feb 20, 2025  Peer-reviewedLead authorCorresponding author
    Abstract Purpose The energy threshold is an important parameter for precise material identification employing photon‐counting techniques. However, in such applications, the appropriate energy threshold has not been clarified. Therefore, we aimed to determine the appropriate energy threshold range for precise material identification, focusing on effective atomic number (Z) values as an index. Methods The atomic number was estimated using a previously proposed algorithm and Monte Carlo simulations. This algorithm included three steps: calculating the attenuation factor from the incident photon counts on a photon‐counting detector, correcting the beam‐hardening effects, and estimating the atomic number from the attenuation factor index using the calibration curve. Monte Carlo simulations were performed to add Poisson noise to an ideal x‐ray spectrum. The total number of incident x‐rays was set in the range of 103–106. The x‐ray spectra were generated at tube voltages of 50–120 kV. Polymethyl methacrylate (Z = 6.5) and aluminum (Z = 13) were used for the analysis. The energy threshold was varied at intervals of 1 keV to estimate the atomic number. We evaluated the appropriate energy threshold range for accurately estimating the atomic number using the obtained atomic number data and statistical uncertainty under various conditions. Results The appropriate energy threshold range was found to be 31–38 keV for a tube voltage range of 50–120 kV. At this energy threshold, the atomic number can be estimated within an accuracy of ± 0.7 at 105 counts for the atomic number range of 6.5 (PMMA) to 13 (Al). Conclusions We found the appropriate energy threshold range. The findings of this study are expected to be useful for appropriately setting the energy threshold during precise material identification using photon‐counting detectors for clinical applications.
  • Yuta Matsunaga, Tomonobu Haba, Masanao Kobayashi, Shoichi Suzuki, Yasuki Asada, Koichi Chida
    Radiation protection dosimetry, Mar 14, 2024  Peer-reviewed
    This study aimed to assess fetal radiation exposure in pregnant women undergoing computed tomography (CT) and rotational angiography (RA) examinations for the diagnosis of pelvic trauma. In addition, this study aimed to compare the dose distributions between the two examinations. Surface and average fetal doses were estimated during CT and RA examinations using a pregnant phantom model and real-time dosemeters. The pregnant model phantom was constructed using an anthropomorphic phantom, and a custom-made abdominal phantom was used to simulate pregnancy. The total average fetal dose received by pregnant women from both CT scans (plain, arterial and equilibrium phases) and a single RA examination was ~60 mGy. Because unnecessary repetition of radiographic examinations, such as CT or conventional 2D angiography can increase the radiation risk, the irradiation range should be limited, if necessary, to reduce overall radiation exposure.
  • Tomonobu Haba, Yusei Nishihara, Yasunori Saito, Takeshi Tomimura, Shuta Ogawa, Kaho Tanabe, Yasuki Asada, Masanao Kobayashi, Shuji Koyama
    Physica Medica, 118, Feb, 2024  Peer-reviewedLead authorCorresponding author
  • Katsunori Yamashita, Hiroyuki Ueno, Tomonobu Haba, Yusuke Ito, Yuta Matsunaga, Ayaka Hirosawa, Souichirou Ishizaki, Masato Mizui, Mitsuharu Osawa, Takayuki Nomura, Satoshi Mogi
    Japanese Journal of Radiological Technology, 79(3) 241-251, Feb, 2023  Peer-reviewed

Misc.

 11
  • 羽場友信
    計測部会誌, (Vol.31,No.2,通巻62), Oct, 2023  
  • 羽場友信
    計測部会誌, (Vol.31,No.1,通巻61), Mar, 2023  
  • Tomoki Shibahara, Shuji Koyama, Masaki Inoue, Tomonobu Haba
    Proceedings of the Twenty-Second EGS User's Meeting in Japan, 19-24, 2015  
    There has been a growing concern regarding exposure to superficial radiosensitive organs with the rapid increase of computed tomography examinations. Manufacturers have been developing various dose reduction methods in order to prevent harm to these organs. Our previous study revealed a unique phenomenon in X-ray computed tomography scanning, in which the maximum absorbed dose position shifts to a deeper region from the surface in a water cylindrical phantom. We considered that this result could be applied as a dose reduction method. Therefore, in this study, we investigate the tube voltage dependence of this unique phenomenon. The results show that the peak dose position shifts to a deeper region with increasing tube voltage. The superficial radiosensitive organs can thus be protected from peak dose exposure by adjusting the tube voltage.
  • Masaki Inoue, Shuji Koyama, Tomonobu Haba, Tomoki Shibahara
    Proceedings of the Twenty-Second EGS User's Meeting in Japan, 14-17, 2015  
  • Tomonobu Haba, Shuji Koyama, Yoshihiro Ida
    Radiological Physics and Technology, 7(1) 133-140, 2014  Peer-reviewed
    The longitudinal dose profile in a computed tomography dose index (CTDI) phantom had been studied by many researchers. The cross-sectional dose profile in the CTDI phantom, however, has not been studied. It is also important to understand the cross-sectional dose profile in the CTDI phantom for dose estimation in X-ray CT. In this study, the cross-sectional dose profile in the CTDI phantom was calculated by use of a Monte Carlo (MC) simulation method. A helical or a 320-detector-row cone-beam X-ray CT scanner was simulated. The cross-sectional dose profile in the CTDI phantom from surface to surface through the center point was calculated by MC simulation. The shape of the calculation region was a cylinder of 1-mm-diameter. The length of the cylinder was 23, 100, or 300 mm to represent various CT ionization chamber lengths. Detailed analyses of the energy depositions demonstrated that the cross-sectional dose profile was different in measurement methods and phantom sizes. In this study, we also focused on the validation of the weighting factor used in weighted CTDI (CTDIw). As it stands now, the weighting factor used in CTDI w is (1/3, 2/3) for the (central, peripheral) axes. Our results showed that an equal weighting factor, which is (1/2, 1/2) for the (central, peripheral) axes, is more suitable to estimate the average cross-sectional dose when X-ray CT dose estimation is performed. © Japanese Society of Radiological Technology and Japan Society of Medical Physics 2013.
  • ISHII Takanori, KONDO Shinpei, HABA Tomonobu, HAYASHI Daiki, NUMAMOTO Hitomi, KOYAMA Shuji
    Proceedings of the Nineteenth EGS Users' Meeting in Japan, 48-52, Oct, 2012  
    In this study, the absorbed dose for organs in infant, child, and adult patients undergoing head computed tomography (CT) scans was determined. The CT examinations were simulated using the Electron Gamma Shower ver. 5 (EGS5) Monte Carlo code. The eye lens dose among child and infant patients was higher than that among adult patients by 15.0% and 69.7%, respectively. The effectiveness of a bismuth shield in reducing the eye lens dose for children undergoing head X-ray head CT scans was also evaluated. Application of a bismuth shield over the eyes of children undergoing head X-ray CT reduced the eye lens dose by 47.6% from the dose value in the case wherein shielding was not used. The use of metallic shields was found effective in reducing the radiation dose to children.
  • HABA Tomonobu, KONDO Shimpei, HAYASHI Daiki, TAKEUCHI Akihiko, ISHII Takanori, NUMAMOTO Hitomi, KOYAMA Shuji
    Proceedings of the Nineteenth EGS Users' Meeting in Japan, 1-3, Oct, 2012  
    In this study, we validated the effectiveness of using a message passing interface (MPI) method in reducing computation time and enhancing calculation accuracy. A chest and abdominal X-ray computed tomography scan was simulated. Our results indicated that the MPI method was accurately incorporated into the Electron Gamma Shower ver. 5 (EGS5) MC code. The MPI method could reduce computation time from 34 hours to 6 hours. We believe that MC simulation is going to be used widely. Therefore, incorporating the MPI method into EGS5 is very useful for EGS5 users.
  • HABA Tomonobu, KOYAMA Shuji
    Proceedings of the Eighteenth EGS User's Meeting in Japan, 58-61, Oct, 2011  

Presentations

 47

Teaching Experience

 11

Research Projects

 6

Other

 2