X-rays are mainly used to judge bone age. Generally, the wrist is the most ideal. A large number of long bones, short bones and round bones are concentrated here, which reflects the growth and maturity of the whole body bones. The projection method is simple and does little harm to the human body. Sometimes elbows, knees, ankles and skulls can be X-rayed as needed. In order to further judge bone age and distinguish diseases. There are three main points to judge the degree of bone calcification: ① the number and size of ossification centers; ② Morphological changes of ossification center and epiphysis; ③ Healing of epiphysis and diaphysis. A person's bone age can be judged by comparing the bone age standards used as normal values.
If it's archaeology.
In archaeology and forensic identification, there are many ways to judge sex through bones, which can be divided into two categories: comparative observation and instrumental measurement. The former refers to judging gender by observing the morphological differences of bones with naked eyes. Generally speaking, male bones are thick, the surface is rough, and the muscle attachment is obvious. It can also be judged by pelvis: the upper mouth of female pelvis is larger. This difference has been shown since the fetal period. In addition, there are some gender differences in skull, sternum, clavicle, scapula and long bones of limbs. The latter refers to measuring the length, width, height, angle and thickness of human remains with a bone measuring instrument. Comparing the obtained data with the male average and the female average; Or according to the corresponding mathematical means, the data is substituted into the regression function for calculation. Then judge the gender. Bones can also tell us the age of the deceased. Many factors will affect the shape of bones, so when identifying age from bones, many methods are often used to verify each other. Many skeletal features change regularly with age. For example, at the age of 30~40, the ossification center of costal cartilage increases, and the sternal stalk and sternal body heal. At the age of 40~50, the sternum and xiphoid process healed, and the larynx and costal cartilage began to solidify. Over the age of 60, the whole body cartilage will ossify. For the age identification of adult bones, it is common to observe and compare the morphological changes of bones. In childhood, there are many organic components in bone tissue, which make bones have high toughness and low hardness. In adulthood, the proportion of inorganic substances gradually increases. At this time, bones are not only hard, but also have good elasticity and toughness. In old age, inorganic components further increase and bones become brittle. At the same time, under the action of bone hyperplasia and absorption, the shape of bone has also changed accordingly. Observing pubic symphysis is one of the best methods to estimate the age of adult and later bones. Based on the skeletal characteristics here, the error can be controlled within five years, and if the age of death is between 20 and 40, the error can even be reduced to two years. In archaeological excavations, skulls are generally well preserved, and many clues for dating can be found here. The skull consists of 29 bones, all of which are connected by seams except the mandible. Although the healing speed of most cranial sutures varies greatly among individuals, it can still provide valuable information for the division of age. For example, the healing time of skull base suture is relatively stable, generally at the age of 20~25. By observing the fusion of basal suture, it can be judged whether the owner of the skeleton is an adult. When people enter old age, the seams completely merge and disappear. According to this information, experienced experts can roughly judge the age of their death with the naked eye.