DEVELOPMENT OF GLOBAL STANDARD PHANTOM TO OPTIMIZE DIGITAL

本研究的目的是开发一个标准的体模牙科X线摄影和比较的图像质量的电影和数字获取images.First，铝块的12个步骤，7孔覆盖丙烯酸块被开发。在3种不同的管电压下，使用两种类型的胶片对该体模进行射线照相。通过计数每次曝光时的最大可感知孔来生成修改的感知曲线。根据该曲线确定了最佳曝光量，并与标准铝阶梯楔和X线机预置时间确定的曝光量进行了比较。该体模的X射线衰减范围似乎接近临床条件。此外，图像质量的差异可以通过在体模中看到的孔的数量来评估。接下来，通过使用该体模，比较了2种胶片系统和几种数字口内系统的视觉图像质量。修改后的感知曲线的创建和相互比较。除了迪戈拉系统外，所有数字系统的最佳曝光都低于E速胶片。然而，在所有没有增强的数字图像中，可感知的孔的最大数量明显低于该曝光的胶片系统。对比度增强后，除Sens-A-Ray系统外，所有数字系统的可见度均优于胶片系统。使用CDR、迪戈拉和Dixel系统，曝光量可以显著减少，信息保留比使用胶片更好。这些结果强烈表明，如果使用得当，数字系统在检测微小质量变化方面可以超过胶片系统。

The purpose of this investigation was to develop a standard phantom for dental radiography and to compare image quality of film and digitally acquired images.First, an aluminum block of 12 steps with 7 holes covered by acrylic blocks was developed. This phantom was radio graphed with two types of films at 3 different tube voltages. The modified perceptibility curve was generated by counting maximum perceptible holes at each exposure. Optimum exposure level was determined from this curve and compared with that determined by means of the standard aluminum stepwedge and the preset time o the x-ray machine. The x-ray attenuation range for this phantom seemed to approximate clinical conditions. In addition, differences in image quality could be evaluated by means of the number of the holes seen in the phantom.Next, 2 film systems and several digital intraoral systems were compared with regard to visual image quality through use of this phantom. Modified perceptibility curves were created and compared each other. All digital systems except the Digora system showed lower optimum optimum exposures than E-speed film. In all digital images without enhancement, however, the maximum number of perceptible holes was significantly lower than that for the film systems at that exposure. With contrast enhancement, all digital systems except the Sens-A-Ray system showed visibility superior to that of the film systems. With CDR, Digora, and Dixel systems, exposures could be reduced by a considerable amount, with greater retention of information than was associated with film.These results strongly suggest that digital systems, if properly used, can exceed film systems in the detection of small mass changes.