This part of IEC 62494 specifies definitions and requirements for the EXPOSURE INDEX of images acquired with DIGITAL X-RAY IMAGING SYSTEMS. This standard is applicable to DIGITAL X-RAY IMAGING SYSTEMS used in general radiography for producing PROJECTION X-ray images for general applications, such as, but not exclusively: • computed radiography (CR) systems based on stimulable phosphors; • flat-panel detector based systems; • charge-coupled device (CCD) based systems. Image intensifier based systems and systems for mammographic or dental application are not covered in this first edition. This standard defines the EXPOSURE INDEX only for images generated with a single IRRADIATION event. Images generated from multiple IRRADIATIONS (e.g., tomosynthetic or dualenergy images, multiple views on a single CR plate) are not covered.