What is the focal length of adult shoulder photography?

X-rays include quality and quantity. The quality is determined by the kv of X-ray machine, which refers to the penetration of X-rays into human body, and the quantity is determined by mAs, which refers to the sensitivity of X-rays to film. Only when kv matches mAs can qualified X-rays be obtained.

When shooting, the 200mA camera is set to 100mA, and the chest radiograph is usually set to 0.2s (second), that is, 20mAs, about 65kv, with the focal length of 1.5m, and the limbs are generally 12-20mAs, [40+ body thickness (cm)]kv, with the focal length. General perspective with 3-5 mA, 65 kV.

The above conditions are for reference only, and should be adjusted according to the machine performance and film processing conditions during normal use.