金属容器或其他制品在制造、焊接、加工过程中有时在其内部留下空洞、缝隙或其他疵点。在容器或制品使用时，这些疵点往往会导致重大事故。例如高压容器焊接不牢或有砂眼，可能会发生爆炸；大炮炮弹有空洞，有可能发射前就在炮筒中自爆。利用X射线、伽玛射线穿过物体后使照相胶 Metal containers or other articles sometimes leave hollows, gaps or other imperfections in the interior of their manufacture, welding, and processing. These defects often lead to major accidents when used in containers or articles. For example, high pressure vessels are poorly brazed or have a blown eye, explosions may occur; artillery shells are empty and may explode in the barrel before firing. Using X-rays, gamma rays pass through the object to make the photo-adhesive