Bone age assessment method that involve left hand and wrist radiographs. The GP method is an atlas method in which bone age is evaluated by comparing the radiograph of the patient with the nearest standard radiograph in the atlas. The GP method was developed using radiographs of upper-middle class Caucasian children in Cleveland, Ohio, United States, and the radiographs were obtained between 1931 and 1942.

Tanner-Whitehouse system 2nd edition (1983). Bone age assessment method that involve left hand and wrist radiographs. The 20-bones method evaluates the 13 long or short bones and 7 carpals. The TW2 method is a scoring method. Firstly, the maturity level of each bone is categorized into a stage (from stage A to H or I). Afterwards, each stage is replaced by a score, and a total sore is calculated. Finally, the total score is transformed into the bone age. The TW2 method was developed using radiographs of average socioeconomic class children in the United Kingdom, and the radiographs were collected in the 1950s and 1960s.

Tanner-Whitehouse system 2nd edition (1983). Bone age assessment method that involve left hand and wrist radiographs. The radius-ulna-short bones (RUS) method evaluates the 13 long or short bones (i.e., the radius, ulna and short bones of the first, third and fifth fingers). The TW2 method is a scoring method. Firstly, the maturity level of each bone is categorized into a stage (from stage A to H or I). Afterwards, each stage is replaced by a score, and a total sore is calculated. Finally, the total score is transformed into the bone age. The TW2 method was developed using radiographs of average socioeconomic class children in the United Kingdom, and the radiographs were collected in the 1950s and 1960s.

Tanner-Whitehouse system 3rd edition (2001). Bone age assessment method that involve left hand and wrist radiographs. The 3rd edition updates the relationship between the total bone maturity score and bone age based on secular trend. The TW3 method is a scoring method. Firstly, the maturity level of each bone is categorized into a stage (from stage A to H or I). Afterwards, each stage is replaced by a score, and a total sore is calculated. Finally, the total score is transformed into the bone age.