Normalised Instance

lilatac Normalised objects are like Composite_Objects in that they persist from one operation to another (normally in an SCP) but unlike Composite Objects, they only make sense in the context of other objects around them. Common examples of Normalised Object are:

Basic Film Box

acnobopas A Basic Film Box is a Normalised_Instance which represents a particular sheet of film to be created during Printing as requested by the SCU. Its properties control aspects such as the size, image format, background density etc.

Service Class Provider

SCP is an acronym for "Service Class Provider" which is the weird DICOM term for a server application. All DICOM network communications occur between an SCP and a Service_Class_User-_SCU


As association is the DICOM term for a network connection between two applications, one of which is the Service_Class_User (SCU - client) and the other is the Service_Class_Provider (SCP - server). It is basically a TCP connection, but with extensive negotiation between the two entities to agree which SOP_Classes and options they both support.

Basic DICOM Operations

DICOM services use a limited number of basic DICOM operations (officially called DIMSE operations), all of which are of course supported by DicomObjects.


PACS, picture archiving and communication systems, is a set of computers connected by a network, and dedicated to the storage, retrieval, distribution, and presentation of medical images. A PACS is independent of the format of the information.

The Digital Imaging and Communications in Medicine (DICOM) standard format is the most common format for medical image data found in PACS.

Composite Instance

A Composite Instance is the official DICOM term for a persistent storable object. Whilst most composite instances are Images (with pixel data), DICOM has plenty of other Composite Instance types, such as:

Special Labels

DicomLabels of type doLabelSpecial are used where the text content is determined by DicomObjects rather than by the programmer. The first use is for anatomic side markers, but the more general name has been used, as other types may be used in the future.

Anatomic side markers are created by setting the Text property of the DicomLabel to one of the following 4 values:

Rendering Structured Reports

We are often asked whether DicomObjects (COM or .NET) "supports" DICOM Structured_reports, so this page exists to give an explanation of what DicomObjects does and does not do.

Of course, DicomObjects as always provides full access to the data within any DICOM object, and it can handle the reading, writing and network transmission of Structured reports just the same as it can for images, or any other sort of DICOM object - that is a standard function of DicomObjects!

Transfer Syntax

Transfer Syntax is the language used in DICOM to describe the DICOM file format and the network transfer methods. 3 main variables are contained in the Transfer Syntax:

  • VR: Implicit/Explicit
  • Endianism: Little-Endian/BigEndian
  • Pixel Data Compression

Transfer Syntax is in the File Meta Header and more information about how to control the network transfer using Transfer Syntax can be found here.

Here is a summary of the most common DICOM Transfer syntaxes:


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