Abstract
In this thesis, a fully automatic bone age development using the area ratio of carpals has been proposed, including preprocess, feature extraction, bone age assessment. Preprocess consists of cropping left hand image, removing background, and extraction of carpals' region of interest (ROI). Using radiograms bottom center as the center of a circle to do counter clock scan. Calculate the magnitude of nonzero gray level on scan lines with all angles. Find the right boundary of left hand image by smallest magnitude of scan lines to cropping left hand image. Transform the left image to binary through using mean value of left hand image pixel’s gray level as the threshold. Eliminate the unneeded label, right hand, and background by reserving the maximum group. Through information of ulna and radius, we can extract reliable carpal’s ROI. In feature extraction section, restrain unneeded soft tissue and texture by using gray level cumulative distribution function of pixel location as the weight. By dilating, filling airtight region, and eroding to extract carpals. Use the area ratio of carpals as the characteristic to accomplish the bone age assessment. Separate the carpal’s area ratio to three stages according to characteristics of the bone ages. Use different methods to accomplish classified bone age assessment at different stages. In addition to assist physician's clinical diagnosis with the assessed bone age, the carpals ROI image can provide physician and radiologist with Tanner-Whitehouse (TW) method. The dataset images which we adopted are beyond 3500. The successful rate of preprocess reaches almost ninety percent. The successful rate which the error of bone age is under 1.5 years old reaches nearly eighty percent. At stage of the youngest bone age, the successful rate which the error of bone age is under 1.5 years old reaches nearly ninety percent. The experiment result conforms to clinical research. The age is usually younger by accomplishing bone age assessment with carpals. After the age is beyond 9-12, accomplishing bone age assessment with phalanx is more reliable.