What are the characteristics of the selection of chest radiography conditions?

① Selection of tube voltage: Under the condition of effectively eliminating stray lines, high-voltage photography technology is selected, and 100 ~ 125kvp is generally selected. ② Photography distance: 180cm. ③ Photography time: 0.05 ~ 0.01s. ④ The influence of the proportion of chest tissue components on the chest type: The chest type involves the proportion of chest tissue components. General chest types can be divided into ordinary (standard), obese, barrel and pediatric types, and the photographic conditions of obese type with the same thickness are improved by 25% ~ 30% compared with ordinary type. The chest of the bucket should be lowered, especially the chest photography conditions of infants, which cannot be calculated simply by thickness. Because of its fat chest wall, small lung tissue, large cardiothoracic ratio, vigorous lymph and developed thymus. ⑤ Pathological factors: The pathological changes of chest diseases are complicated and difficult to master. The key is to find out the relationship between pathological changes and X-ray absorption.