Research Article A Prototype Intraoral Periapical Sensor with High Frame Rates for a 2.5D Periapical Radiography System Che-Wei Liao , 1,2 Ker-Jer Huang, 2 Jyh-Cheng Chen , 3 Chih-Wei Kuo, 2 Yin-Yi Wu , 2 and Jui-Ting Hsu 4,5 1 Graduate Institute of Biomedical Sciences, China Medical University, Taichung 404, Taiwan 2 Materials & Electro-Optics Research Division, National Chung-Shan Institute of Science & Technology, Taoyuan City 407, Taiwan 3 Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei 112, Taiwan 4 School of Dentistry, College of Dentistry, China Medical University, Taichung 404, Taiwan 5 Department of Bioinformatics and Medical Engineering, Asia University, Taichung 413, Taiwan Correspondence should be addressed to Yin-Yi Wu; davidwu0801@gmail.com and Jui-Ting Hsu; jthsu@mail.cmu.edu.tw Received 14 February 2019; Accepted 2 April 2019; Published 24 April 2019 Guest Editor: Yuan-Chiao Lu Copyright © 2019 Che-Wei Liao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. X-ray radiography is currently used in dentistry and can be divided into two categories: two-dimensional (2D) radiographic images (e.g., using periapical film, cephalometric film, and panoramic X-ray) and three-dimensional (3D) radiographic images (e.g., using dental cone-beam computed tomography (CBCT)). Among them, 2D periapical film images are most commonly used. However, 2D periapical film compresses 3D image information into a 2D image, which means that depth cannot be identified from the image. Such compressed images lose a considerable amount of information, reducing their clinical applicability. A 2.5D periapical radiography system prototype was developed by our research team. Our previous study indicated that this prototype could be used to capture images at different depths of an object. However, the prototype was limited by its commercially available intraoral periapical sensor, which had a low temporal resolution and could not capture multiple images in a short period of time. Therefore, the total time required for image capture was too long for practical clinical application. The present study developed a high-frame-rate intraoral periapical sensor with a sensor imaging speed of up to 15 Hz. The primary components of the developed intraoral periapical sensor include a scintillator, complementary metal oxide semiconductor chip, component circuit board, and video processing board. The external dimensions of the sensor are 41 × 26 × 6 6 mm 3 . The performance of the developed high-frame-rate intraoral periapical sensor was verified through qualified and quantified analyses using line pairs. The results showed that the resolution of the developed intraoral periapical sensor could reach 18 lp/mm. The sensor was further installed in our 2.5D periapical radiography system to conduct image capturing. The results indicated that the developed sensor could be used for high-frame-rate imaging to incorporate tomosynthesis to obtain reconstructed slice images of different depths. The developed sensor has the potential for clinical dentistry applications in the future. 1. Introduction Since X-ray was discovered by Wilhelm Conrad Röntgen more than 100 years ago, it has been widely applied in med- icine. X-ray can be used for noninvasive medical examina- tions and is one of the methods often used to assess hard tissue before surgery [1]. X-ray imaging requires a sensor to capture the image. In the early days of X-ray technology, radiographic films were applied to capture images. In the past 30 years, sensors for X-ray imaging have gradually been digitalized [2], and digital radiography can now be divided into three categories, namely, computed radiography (CT), indirect digital radiography, and direct digital radiography [3, 4]. In dentistry, the most common application of X-rays is periapical film, which has advantages such as high resolu- tion, easy operation, and low costs [5, 6]. However, periapical film can only provide two-dimensional (2D) images; specifi- cally, three-dimensional (3D) tissue compressed projection can only be displayed in a 2D image. In such 2D images, 3D tissues with different depths are relatively difficult to Hindawi Applied Bionics and Biomechanics Volume 2019, Article ID 7987496, 9 pages https://doi.org/10.1155/2019/7987496