1.1Information Object Definition (IOD）
An Information Object Definition (IOD) is the specification used to define an abstract data object (the information to exchange). The goal of an IOD is to provide an unambiguous specification about related pieces of information. IODs do not represent a specific instance of the data object, but rather a class of similar data objects which have the same properties.IODs provide the mechanisms to specify data objects such as images (e.g., MR, CT, NM,etc.) and also image related data objects such as curves, overlays, Radiology Information System (RIS) information, etc.
In DICOM an IOD consists of an Entity Relationship Model, information entities, modules,and attributes. The content of an IOD is similar to a memo. A memo consists of words (called attributes), sentences (a set of related words, called modules), paragraphs (a set of related sentences, called information entities), and finally the memo (a set of relatedparagraphs, described by an Entity Relationship Model).
1.2 DICOM Message Service Element (DIMSE) Services
Specifying an IOD is key for communication. However, it is not sufficient. Services(methods) which operate on IODs need to be standardized. DICOM defines a set of generic services (such as Store, Create, Delete, Get, etc.) which act upon instances of an IOD. These services are called the DICOM Message Service Element (DIMSE).
3、Service Object Pairs(SOP)Class
The coupling of one or more DIMSE Services with one specific IOD results in a Service Object Pair Class (SOP Class). A SOP Class specification contains the rules which are applied to the DIMSE Services and a related IOD. A SOP Class is equivalent to an “object class” in the object-oriented model (the data plus the methods).A SOP Class is the key specification building block for the successful communication between two AEs. However, like the IOD, the SOP Class does not represent a specific instance of communication. When a specific instance of communication does occur it is defined as a SOP Instance. SOP Instances are used to represent real-world occurrences of images, studies, patients, etc.The analogy of a sentence can be used to describe the MR Storage SOP Class. The IOD acts as the noun (an MR image). The DIMSE Service acts as the verb (Store). The SOP Class is similar to a generic sentence (Store an MR image). The SOP Instance is similar to a specific sentence (Store this MR image).[/FONT] |
发表于 2004-4-8 16:31:30
发表于 2004-4-9 13:26:13