DICOM Supplement 32 defined Information Object Definitions (IODs) and corresponding Storage SOP Classes for Digital X- ray (DX) projection image. The scope of the Supplement was to support DX imags produced by Flat Panel (FP) detectors, Computed Radiography (CR) and Digitized Film (DF) images. We thought it may be necessary to have more attributes to fully describe CR and DF images, especially those related to QA. Using Object Oriented Analysis, we analyzed the acquisition process of x-ray projection image and extracted attributes which should be added to DX IOD. The DX equipment should include x-ray equipments as well as imaging devices. The imaging devices were classified into three classes, CR, DF and FP Equipment Class, and the corresponding Information Modules (IM) were defined. The attributes of each class were classified in to two IMs, the Specification Modules and the Condition/Acquisition Modules. All the added elements were user optional attributes. The newly defined objects were, therefore, classified into Extended DX SOP Class and could be processed by many DICOM SCPs/SCUs conforming to DICOM DX IOD defined in Supplement 32.