A fractal analysis of bone phantoms from digital images.
- Author:
Jae Duk KIM
1
;
Jin Soo KIM
;
Chang Yul LEE
Author Information
1. Department of Dentomaxillofacial Radiology, Oral Biology Research Institute, Chosun University, Korea. jdakim@chosun.ac.kr
- Publication Type:Original Article
- Keywords:
Radiography;
Dental;
Fractals;
Bone;
Image Processing
- MeSH:
Bone Density;
Copper;
Cytochrome P-450 CYP1A1;
Fractals*;
Humans;
Mandible;
Radiography;
Radiography, Dental;
Skeleton
- From:Korean Journal of Oral and Maxillofacial Radiology
2005;35(1):33-40
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
PURPOSE: (1) To analyse the effect of exposure time, ROI size and one impact factor in the image processing procedure on estimates of fractal dimension; and (2) to analyse the correlated relationship between the fractal dimension and the Cu-Eq value (bone density). MATERIALS AND METHODS: The cylindric bone phantoms of 6 large and 5 small diameter having different bone densities respectively and human dry mandible segment with copper step wedge were radiographed at 1.0 and 1.2 sec esposure (70 kVp, 7 mA) using one occlusal film and digitized. Eleven rectangular ROIs from 11 cylindric bone phantoms and 4 rectangular ROIs from cortical, middle, periodontal regions, and socket of bone were selected. Gaussian blurred Image was subtracted from original image of each ROI and multiplied respectively by 1, 0.8, and 0.5, and then the image was made binary, eroded and dilated once, and skeletonized. The fractal dimension was calculated by means of a box counting method in the software ImageJ. RESULTS: The fractal dimension was decreased gradually with continued bone density decrease showing strong correlations (bone phantom; r> 0.87, bone; r> 0.68) under 70 kVp 1.0 sec M = 0.8. Fractal dimensions showed the significant differerence (p< 0.05) between two different exposure times on the same small ROI of bone phantom. Fractal dimensions between two different sizes of ROI on bone phantom showed the significant differerence (p< 0.05) under 1.2 sec exposure, but did not show it (p> 0.05) under 1.0 sec exposure. CONCLUSIONS: Exposure time, ROI size, and modifying factor during subtracting could become impacting on the results of fractal dimension. Fractal analysis with thoroughly evaluated method considering the various impacting factors on the results could be useful in assessing the bone density in dental radiography.
