The Assessment on the Characteristics of Quantitative image in Digora(R)

Kim, Jae Duk

Abstract

PURPOSE: To clarify the usefulness and the limitation of Digora system(R) by evaluating the characteristics as the quantitative image on Image Plate(IP).
MATERIALS AND METHODS
Radiograms were taken by Heliodent MD(Siemens Co., Germany) with the image plate for adult, Cu-step wedge as reference material, and three pieces of dry mandibular bone. Image analysis was performed by single color enhancement, density measurement with histogram. The relationship between the exposure conditions and the distribution of the pixel values of the image, the variation of pixel values of each step of Cu-step wedge at two different area and Cu-equivalent value of three pieces of dry mandibular bone measure by conversion equation.
RESULTS
There was no linear relationship between the exposure condition and the average pixel value of the image, of which the distribution was not even. The pixel value differences between the center portion and the periphery were ranged from 60 to 70 in vertical plane and from 15 to 26 in horizontal plane. Two curves formed at two different areas of the Cu-step wedge were different. The measured Cu-equivalent values showed the discrepancy among the times of measurement.
CONCLUSION
As above results, Image Plate(IP) of Digora system(R) showed the limitation as the quantitative image. The physical property of IP was expected to need to be compensated for the quantitative evaluation of the bone or others.