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154 results on '"Okamura, Kazutoshi"'

9. Relationship between image information content and observer performance in digital intraoral radiography.

Author

Takarabe, Shinya, Okamura, Kazutoshi, Kuramoto, Taku, Tokumori, Kenji, Kato, Toyoyuki, and Yoshiura, Kazunori

Subjects
RESEARCH evaluation, ORAL diseases, DENTAL radiography, INTER-observer reliability, RECEIVER operating characteristic curves, IMAGING phantoms, MEDICAL digital radiography
Abstract

Objectives: This study conducted a receiver operating characteristic (ROC) analysis by applying improved cluster signal-to-noise (CSN) analysis to digital intraoral radiographs and develop an observer-free method of analyzing image quality related to the observer performance in the detection task. Methods: Two aluminum step phantoms with a thickness interval of 1.0 mm were used for this study. One phantom had holes of increasing depth (from 0.05 to 0.35 mm) and the other had no holes. Phantom images were obtained under various exposure dose and image capture modes using a dental X-ray unit, a photostimulable phosphor imaging plate, and scanner system. These phantom images were analyzed using the FindFoci plugin in ImageJ software. Subsequently, true positive rates (TPRs) and false positive rates (FPRs) were calculated by analyzing phantom images with and without holes. We constructed ROC curves by plotting the TPRs against the FPRs and calculated the area under the ROC curve (AUC). Using the same phantom images with holes, eight observers assessed the number of detectable holes. Correlations between observer detection performance and AUC values were evaluated. Results: AUC values increased as the exposure dose increased and showed different tendencies depending on the image capture mode. The AUC values showed a high correlation with observer detection performance (r = 0.76). Conclusions: AUC values obtained from CSN analysis reflect image quality and replace the observer detection performance test of image quality. [ABSTRACT FROM AUTHOR]

Published
2023
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12. Abstracts—Dental radiology vol. 42, 2002

Author

Okamura, Kazutoshi, Yoshiura, Kazunori, Tokumori, Kenji, Tanaka, Takemasa, Kanda, Shigenobu, Shimano, Tatsuya, Suzuki, Yosuke, Sasaki, Takehito, Indo, Hiroko, Suei, Yoshikazu, Yamada, Toshikazu, Taguchi, Akira, Tanimoto, Keiji, Chikui, Toru, Matsuo, Toshiaki, Okamura, Kazutoshi, Miwa, Kunihiro, Yuasa, Kenji, Ikeda, Shohei, Kimura, Yukinori, Sano, Tsukasa, Araki, Kazuyuki, Okano, Tomohiro, Sugawara, Yumiko, Komai, Shinya, Shoji, Noriaki, Kuriwada-Satoh, Shizuko, Furuuchi, Toshi, Onodera, Dai, Iikubo, Masahiro, Sakamoto, Maya, Marumo, Machiko, Takahashi, Kazuhiro, Sasano, Takashi, Takahashi, Akira, Sugawara-Takahashi, Chieko, Uemura, Shusaburo, Haruna, Yoshiro, Hanazawa, Tomomi, Harase, Yuichi, Endoh, Atsusi, Seki, Kenji, Matsuda, Yukiko, Morita, Yasuhiko, Kawano, Kazunori, Sato, Tuyoshi, Majima, Hideyuki, Izumi, Yuichi, Sugihara, Kazumasa, Mimura, Tamotu, Kuroe, Kazuto, Ito, Gakuji, Noikura, Takenori, Nakayama, Hitoshi, Takinami, Shuuichi, Nakamura, Motoyasu, Obinata, Ken-ichi, Ohmori, Keiichi, Yamano, Shigeru, Hamahira, Sumiko, Sawamura, Tsuyoshi, Minowa, Kazuyuki, Morita, Yoasuhiko, Honda, Eiich, Indou, Hiroko, Kato, Tuguhisa, Harata, Yasuo, Kawano, Kazunori, Sato, Tuyoshi, Majima, Hideyuki, Izumi, Yuichi, Sasaki, Takehito, and Kimura, Hiroyuki

Published
2003
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19. Metal artefact reduction in the oral cavity using deep learning reconstruction algorithm in ultra-high-resolution computed tomography: a phantom study

Author

Sakai, Yuki, primary, Kitamoto, Erina, additional, Okamura, Kazutoshi, additional, Tatsumi, Masato, additional, Shirasaka, Takashi, additional, Mikayama, Ryoji, additional, Kondo, Masatoshi, additional, Hamasaki, Hiroshi, additional, Kato, Toyoyuki, additional, and Yoshiura, Kazunori, additional

Published
2021
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26. Effect of differences in pixel size on image characteristics of digital intraoral radiographic systems: a physical and visual evaluation

Author

Kuramoto, Taku, primary, Takarabe, Shinya, additional, Okamura, Kazutoshi, additional, Shiotsuki, Kenshi, additional, Shibayama, Yusuke, additional, Tsuru, Hiroki, additional, Akamine, Hiroshi, additional, Tatsumi, Masato, additional, Kato, Toyoyuki, additional, Morishita, Junji, additional, and Yoshiura, Kazunori, additional

Published
2020
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40. Accuracy of Linear Measurement and the Measurement Limits of Thin Objects with Cone Beam Computed Tomography: Effects of Measurement Directions and of Phantom Locations in the Fields of View.

Author

Tsutsumi, Kimihiro, Chikui, Toru, Okamura, Kazutoshi, and Yoshiura, Kazunori

Subjects
ANALYSIS of variance, STATISTICAL correlation, RADIOGRAPHY, INDUSTRIAL research, DENTAL radiography, TOMOGRAPHY
Abstract

Purpose: The directional dependence of accuracy with cone beam computed tomography (CBCT) has not been investigated thoroughly. The purpose of the present study was to clarify the effects of measurement direction and of phantom locations in the fields of view (FOVs) on the accuracy of linear measurement and on the limits of measuring thin objects with CBCT. Materials and Methods: An aluminum phantom was scanned by CBCT. The thickness in both the longitudinal and horizontal directions (LD and HD) was measured at both the center and periphery in the three FOVs. The length was determined by a 50% relative threshold method to eliminate observer-dependent measurement errors. The measurement limits of a thin object were assessed in thin parts of the phantom (thickness, 0.3 to 1.0 mm). Results: The measurement accuracy in the LD was excellent (within 1 pixel), while that in the HD was fair (0 to 2.35 pixels difference); a slight overestimation was found near the center of the phantom (1.06 to 2.35 pixels difference) in comparison to that of the edges (within 1 pixel difference). The overestimation was more marked at the longitudinal periphery than at the center of each FOV. A thickness of at least three to four pixels was necessary to keep errors within the one-pixel range along both directions. Conclusions: The accuracy of linear measurement with CBCT is excellent, especially when measuring in the LD. Distances are slightly overestimated in the HD near the center of the phantom. Close attention is therefore necessary when planning the placement of implants adjacent to horizontal vital structures. Second, a thickness of at least 3 to 4 pixels was necessary to maintain high accuracy for linear measurement. This must be taken into consideration when measuring a minute structure, such as thin cortical bone. [ABSTRACT FROM AUTHOR]

Published
2011

48. Effectiveness of imaging modalities for screening IgG4-related dacryoadenitis and sialadenitis (Mikulicz’s disease) and for differentiating it from Sjögren’s syndrome (SS), with an emphasis on sonography

Author

Shimizu, Mayumi, primary, Okamura, Kazutoshi, additional, Kise, Yoshitaka, additional, Takeshita, Yohei, additional, Furuhashi, Hiroko, additional, Weerawanich, Warangkana, additional, Moriyama, Masafumi, additional, Ohyama, Yukiko, additional, Furukawa, Sachiko, additional, Nakamura, Seiji, additional, and Yoshiura, Kazunori, additional

Published
2015
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