Quantitative Analysis of the Definition of Rebuilding CT Images Using the Grayscale-Rate

Objective To improve the quality and definition of radiograph for telemedicine, and to master the preferences for rebuilding digital images. Methods Forty two rebuilt CT films were divided into two groups upon the base, then the definition of images was analyzed by calculating the gray scale rate. Results There existed significant difference between two groups on the brightness ( P 0.01) and no difference in group on the resolution. It was found that there is, linear correlation between the gamma value and the brightness, and curvilinear correlation between the gamma value and the gray scales rate in both groups. The peak segment of the curve in group H always goes a little behind that in group L. There was no significant difference between two groups in term of the maximum gray scale rate, the information loss rate, and the composing of the max gray scale rate and the minimum gamma value ( P 0.05). Conclusion The scanning resolution used to rebuild images should double that of the display resolution. And 144ppi is the most suitable for radiograph film in teleconsultation. The most appropriate value of gamma is 3.0 with regard to the contrast resolution; the favorable range of gamma value is between 2.5 and 3.5. The definition and the information loss rate of rebuilt images can be estimated by using gray scale rate. [