Conclusion: Considering the absorbed dose of the patients and avoiding the image distortion, it is suggested that the selection of focus-filmdistance should be matched with the tube and grid.
结论：考虑病人的吸收剂量和避免影像失真，摄影焦-片距的选择应与滤线栅的焦距相匹配。
2
Purpose To establish a screen film system sensitometric method of X ray scale exposure by changing the distance between focus and film.