FEATURE-EXTRACTION IN CARPAL-BONE ANALYSIS

Hand-bone analysis with image processing techniques using a digital radiograph can be used to assess skeletal age. It consists of two steps, phalangeal and carpal bone analysis. This paper presents the carpal bone analysis. First, the carpal bone region of interest (CROI) is defined using a standard thresholding technique to separate the hand from the background. Then, a dynamic thresholding method with variable window sizes is used to differentiate between the bones from the soft tissue. Next, the radius, ulna and metacarpals intersecting the borders of the CROI are removed by using mathematical morphology. Finally, all objects included in the corrected CROI are separated and described in terms of features. These features describe the size, shape, and location. They also include some gray scale pixel value information. On the basis of this analysis the separation of the noncarpal bone objects from the carpal bones is possible. Feature selection step removes features of low discriminant power and reduces the space dimension. The remained carpal bone parameters are used for further analysis leading to the skeletal age assessment.