This part of GB/T 3323 is based on the basic theory and practical experience of digital radiography; specifies the general technology and requirements using computer radiography (CR) technology and digital imaging (DR) technology, which use the digital detector array (DDA), to perform X-and gamma-ray digital detection, for the welded joints of metal materials, including the technical level, general requirements, recommended technologies of X-and gamma-ray digital detection technology (detector system's selection, penetration technology control, image acquisition and display requirements), etc.; specifies the minimum requirements for obtaining digital detection images, which have the equivalent detection sensitivity as the film-based radiographic detection technology, in Part 1 of this standard (GB/T 3323.1).