|Budget Amount *help
¥3,000,000 (Direct Cost : ¥3,000,000)
Fiscal Year 1999 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1998 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1997 : ¥1,400,000 (Direct Cost : ¥1,400,000)
(1) Results from software features of six digital imaging systems for intra-oral radiography. Six digital systems, CDR, PanaDigital(PD), RVG, Sens-A-Ray(SAR), Visualix(VIX) and Digora, were used. Function for the full-mouth survey were evaluated. Software features were classified into three functions, such as image acquisition, image display and image saving. CDR and RVG provided the display disposition to arrange images of the full-mouth survey. Some systems needed several times of clicking prior to acquisition, but no operation for VIX. The period for waiting exposure ranged from 15 sec to an infinity. Automatic exposure compensation was set at PD, RVG and Digora by default. Pixel values were proportional to exposures with CDR, SAR and VIX(linear mode). After the exposure, the captured image was automatically saved with CDR, SAR and Digora. Images were stored in each pateint's directory with CDR, RVG and SAR, Ten-bit storage was employed with PD. The TIF format was adopted by RVG, SA
R andVIX. The RVG and VIX employed the JPEG. Advantages and drawbacks learned through our experiences were clarified. Software features showed differences. These systems are provided for the use at a dental chair side. They should be designed so that operations are not complicated.
(2) Results from the evaluation of the new storage phosphor-based compted radiography system for dental office. The denOptix CR system is applicable for both intraoral and panoramic radiographic examinations. The DenOptix uses an imaging plate. We examined the new features, different pitches for laser-scanning and the automatic range control (ARC). A jaw phantom and a head phantom were used. Images were captured with the ARC working. Laser-scanning pitch was set at either 150, 300 or 600 dpi. A piece of the Dental X-ray Beam Filter Kit reduced X-ray output to 30%. Even when two pieces were used, the DenOptix was still capable of obtaining intraoral images with acceptable image quality. The DenOptix has also the capability of obtaining panoramic images with a little detriment of noise with the lowest exposure. The ARC worked to compensate both under- and over-exposures and resulted the wide exposure range. The compensation of over-exposures may result in images created with an exposure that gives the patient a higher dose than necessary.
(3) Results from the evaluation of a digital panoramic radiography system. The Dimax is adigital panoramic radiography system which uses a stationary, narrow two-dimensional detector in place of a moving cassette. The purpose of this study is to evaluate software features as an interface to the operator and the image quality related to exposure. Software features were evaluated as four major functions, such as image acquisition, display, storage and transmission. The tissue-equivalent phantom was used to evaluate the exposure reduction. Some excellent software features, for example a combination of hardware and software, ease to operate, care of patient' privacy, were found. The inadequate image quality due to under-exposures was avoidable since the exposure compensation and the gamma conversion worked well. To some extent such compensation worked for over-exposures, but the operator could easily recognize exceeded exposures.
4汎用画像処理ソフトウエアImage-Pro Plus(Media Cybernetics,USA)を使用して解析した。画像データのヒストグラムを表示すると,各システムで採用された量子化bit数で示されるスケールの全部あるいは一部分に分布した。このヒストグラムを基にユーザー用データを作成する場合,階調数を減少させるために複数のピクセル値にひとつのディスプレイ濃度値を割り当てる。このような階調処理はその分解能を下げていた。またシステムによって周波数成分の違いが生じていたが,bit数を減少させる適切な処理ができると考えられた。 Less