With the help of transfer syntax communicating entities negotiate on common encoding techniques which they support. Transfer syntax is a set of rules for encoding to unambiguously represent more abstract syntaxes. Value Field: Describes the values of the data elements.Value Length: is he unsigned integer represent the explicit length of the value field.Value Representation VR: VR is a character string which represents the VR of the data Element.Data Element Tag: An ordered integer which represents the group number and element number.Basic Three types of data element structures are as follow.ĭata Element with an Explicit VR Group Numberĭata Element with an Implicit VR Group Number There are 5 types of Data elements namely Type 1 Required Data elements, Type 1C Conditional Data Elements, Type 2 Required Data Elements, Type 2C Conditional Data Elements and Type 3 optional Data Elements. Data Elementsĭata element consists data element Tag, Value length and value for the Data Element. A DICOM data object consists of a number of attributes, including items such as name, ID, etc., and also one special attribute containing the image pixel data. Structure of attributes is specified in IODs. Data set contains data elements and data elements contain values of the attributes of that object. Data set is the representation of real world information. Data SetĮach file must contain a single data set representing SOP instance and SOP Class with related IOD. Prefix contains the string “DICM” as uppercase characters. Preamble is used to access the images and other data in DICOM file providing compatibility with commonly used image file formats.
Preamble # 128 Bytes| Prefix # 4 Bytes “D, I, C, M The file header contains 128 byte File Preamble, and 4 byte DICOM prefix. HTTP and HTTPS protocols are used for the web services of DICOM. DCM Format 1.x is further available in two versions normal and extended. DCM extension.DCM exist in two different formats i.e. DICOM File FormatĭICOM is the combination of file format definition and a network communications protocol. 3.0 is still the latest version but it has been continuously updated since 1993. The 3rd version of the standard was released in 1993 as “DICOM”. The second version was released in 1988 which was more popular among vendors, but soon it was realized that second version also needs improvement. Initially, it was hard to decode the images that the machines produced. Therefore, ACR and NEMA together formed a team in 1983 which released its first standard, ACR/NEMA 300 in 1985. HistoryĭICOM was developed jointly by American College of Radiology (ACR) and National Electrical Manufacturers Association (NEMA) for the exchange and viewing of medical images like MRIs, CT scans and ultrasound images. Versions supported by web services are 1.0, 1.1, 2 or later. The communication part of DICOM is application layer protocol and uses TCP/IP to communicate between entities. DICOM files can be shared between two parties if they are capable of receiving image data in DICOM format. DICOM is used for the integration of medical imaging devices like printers, servers, scanners etc from various vendors and also contains identification data of each patient for uniqueness. DICOM is the acronym for Digital Imaging and Communications in Medicine and pertains to the field of Medical Informatics.