Assessment of bone age is one of the subjects frequently treated in pediatrics. The left hand of a child is imaged using X-Ray and the image is used to assess a bone age. The bone age assessment is an important indicator that can confirm whether a child develops normally. If there is a large discrepancy between an actual age and a measured bone age, it may be determined that there is an abnormality in bone growth (diabetes, genetic disease, etc.) and an appropriate treatment may be provided. A method for assessing a bone age from an X-ray image obtained by imaging the left hand includes Atlas and TW2 matching methods.
The Atlas matching method, which is proposed by Greulich and Pyle in the United States, evaluates a left hand radiographic image with a book containing radiographic images of the Atlas pattern group arranged according to age and sex. A physician will look at an image most similar to an overall shape of a child's X-ray image from the book of the Atlas pattern group to evaluate a bone age. Currently, 76% of physicians who evaluate bone age use this method. However, the Atlas matching method is highly likely to cause an error in the process of evaluating a bone age due to the degree of skill of a physician and a variation in bone growth of people.
Another method to assess a bone age is the TW2 method proposed by Tanner and Whitehouse in the UK. According to this method, each bone of the left hand is compared with the images in a book published by the TW2 group, rather than looking at the similarity of the whole image of the bone as in the Atlas matching method. Compared with the Atlas matching method in which similarity is analyzed in the whole image of the bone, in the TW2 method, individual bones are separately analyzed in features, and thus, a bone age can be more accurately measured, relative to the Atlas matching method. However, due to shortcomings in that it takes more time to evaluate a bone age, relative to the Atlas method, the TW2 method is not currently widely used.
According to the method of estimating a bone age using such Atlas or TW2, since a reading specialist evaluates a bone age by visually confirming the similarity of the image with naked eyes, the reliability of the bone age is degraded and much time is taken to estimate the bone age.
In order to solve such problem, Stanley M. Garn published a paper entitled “Metacarpophalangeal Length in the Evaluation of Skeletal Malformation” in 1972. This method, however, was limitedly used only in the white middle class as it simply attempted to measure a bone age by measuring only an absolute length of the bone.