|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1997 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1996 : ¥1,400,000 (Direct Cost : ¥1,400,000)
With the digitalization of information concerning imaging diagnosis, many medical devices for digital imaging have been developed. Digora was developed as a digital imaging system in which an imaging plate (IP) is used as an imaging sensor to obtain images of the oral. Since CRT images are used in such digital imaging systems, we made clinical imaging diagnoses based on CRT images using a Digora system to find an optimal IP,and then we attempted to establish parameters for the evaluation of digital imaging systems in the field of dentistry.
(1) Characteristics of the digital imaging system with IP were examined by enlargement radiography, etc.to determine its usefulness. (2) The imaging format of Digora was converted to the film output for CR,in order to examine the ability of film images in making accurate diagnosis and that of CRT images. (3) The ability of recognizing normal mandibular anatomy was visually compared using a mandibular phantom between CRT images, conventional film imag
es, and film images obtained with Digora. As a result, no differences were observed between those 3 kinds of images. (4) The ability to detect proximal surface caries did not differ between the 3 kinds of images. (5) The ability to diagnose decalcification of spongy bone did not differ neither between the 3 kinds of images. (6) From the findings described in (2), (3), (4), and (5), it was revealed that oral diseases could be accurately diagnosed using CRT images, indicating the unnecessity of film output. (7) When the ability to diagnose clinical cases (caries, radicular cyst, apical periodontitis, and marginal periodontitis) was compared between CRT images and film images, no difference was observed. (8) When irradiation time was compared among different types of IP in the Digora system (HR for Digora ; ST for general radiography ; UR for electron microscopic radiography), diagnosis could be made using a HR while an irradiation time was shortened to 1/4 that of D speed film, indicating that a dose could be reduced by using a HR.(9) When physical imaging properties of 3 types of IP were examined, a high MTF was obtained with UR whereas HR showed a satisfactory NEQ at a low dose. (10) As overall evaluation on the findings obtained in (8) and (9), an optimal IP in the Digora system for clinical cases was determined to be HR.
We demonstrated the significance of evaluation of image sensors and output images in digital imaging systems and established parameters for the evaluation of digital imaging systems. Less