Note - the information here only applies to the .NET version of DicomObjects, and only version 5.6 onwards

Background

All previous versions of DicomObjects, both .NET & COM have shared the same basic mechanism for selecting transfer syntaxes:

• When initiating, they can be created specifically using Contexts.Add etc.
• When accepting, they can be selected specifically using Context.AcceptedTS or Reject
• If neither of the above is used (as most people don't) then a default mechansim is used, based on the TransferSyntax registry hive, which allows:
  • Setting of specific values for different SOP classes using TransferSyntax/SOP_class_UID
  • A more generic setting for all other SOP classes in the TransferSyntax/ default value

This system has worked well for many years, but has 3 main drawbacks:

• It is complicated to set up a different value for each SOP class, and many developers do not know the characteristics of each (especially maximum bit depth)
• Most developers therefore use a generic list of Transfer syntaxes, which are not always appropriate for all SOP classes (e.g. using JPEG lossy baseline for images with > 8 bits such as CT or MR)
• It leads to "compressed" synatxes being offered for services such as C-FIND etc., which (though 100% legal in DICOM) is rather pointless and looks a little unprofessional.

The New System - overview

So......Whilst the old mechanism has been retained for backward compatibility in 5.6, an improved version has been added as an alternative. This provides the following benefits:

• The defaults are more sensible
• It is easier to change the chosen transfer syntaxes for a list of SOP classes in one operation
• Separate lists are maintained for offered and accepted transfer syntaxes

The New System - details

• SOP classes are automatically arranged into different groups, which share common characteristics. The groups are:

Services

DICOM Services such as verification and C-GET etc. Default values are:

"1.2.840.10008.1.1"

"1.2.840.10008.1.9"

"1.2.840.10008.1.20.1"

"1.2.840.10008.1.20.2"

"1.2.840.10008.3.1.2.1.1"

"1.2.840.10008.3.1.2.2.1"

"1.2.840.10008.3.1.2.3.1"

"1.2.840.10008.3.1.2.3.2"

"1.2.840.10008.3.1.2.3.3"

"1.2.840.10008.3.1.2.3.4"

"1.2.840.10008.3.1.2.3.5"

"1.2.840.10008.3.1.2.5.1"

"1.2.840.10008.3.1.2.6.1"

"1.2.840.10008.5.1.1.1"

"1.2.840.10008.5.1.1.2"

"1.2.840.10008.5.1.1.4"

"1.2.840.10008.5.1.1.4.1"

"1.2.840.10008.5.1.1.4.2"

"1.2.840.10008.5.1.1.14"

"1.2.840.10008.5.1.1.15"

"1.2.840.10008.5.1.1.16"

"1.2.840.10008.5.1.1.16.376"

"1.2.840.10008.5.1.1.24.1"

"1.2.840.10008.5.1.1.22"

"1.2.840.10008.5.1.1.31"

"1.2.840.10008.5.1.4.1.2.1.1"

"1.2.840.10008.5.1.4.1.2.1.2"

"1.2.840.10008.5.1.4.1.2.1.3"

"1.2.840.10008.5.1.4.1.2.2.1"

"1.2.840.10008.5.1.4.1.2.2.2"

"1.2.840.10008.5.1.4.1.2.2.3"

"1.2.840.10008.5.1.4.1.2.3.1"

"1.2.840.10008.5.1.4.1.2.3.2"

"1.2.840.10008.5.1.4.1.2.3.3"

"1.2.840.10008.5.1.4.31"

Images8Bit

DICOM Images expected to contain only 8 bit pixel data. Default values are:

"1.2.840.10008.5.1.4.1.1.3"

"1.2.840.10008.5.1.4.1.1.3.1"

"1.2.840.10008.5.1.4.1.1.6"

"1.2.840.10008.5.1.4.1.1.6.1"

"1.2.840.10008.5.1.4.1.1.7"

"1.2.840.10008.5.1.4.1.1.77.1.1"

"1.2.840.10008.5.1.4.1.1.77.1.1.1"

"1.2.840.10008.5.1.4.1.1.77.1.2"

"1.2.840.10008.5.1.4.1.1.77.1.2.1"

"1.2.840.10008.5.1.4.1.1.77.1.3"

"1.2.840.10008.5.1.4.1.1.77.1.4"

"1.2.840.10008.5.1.4.1.1.77.1.4.1"

"1.2.840.10008.5.1.4.1.1.77.1.5.1"

"1.2.840.10008.5.1.4.1.1.7.1"

"1.2.840.10008.5.1.4.1.1.7.2"

"1.2.840.10008.5.1.4.1.1.7.4"

Images16Bit

DICOM Images expected to contain up to 16 bit pixel data. Default values are:

"1.2.840.10008.5.1.4.1.1.1"

"1.2.840.10008.5.1.4.1.1.1.1"

"1.2.840.10008.5.1.4.1.1.1.1.1"

"1.2.840.10008.5.1.4.1.1.1.2"

"1.2.840.10008.5.1.4.1.1.1.2.1"

"1.2.840.10008.5.1.4.1.1.1.3"

"1.2.840.10008.5.1.4.1.1.1.3.1"

"1.2.840.10008.5.1.4.1.1.2"

"1.2.840.10008.5.1.4.1.1.2.1"

"1.2.840.10008.5.1.4.1.1.4"

"1.2.840.10008.5.1.4.1.1.4.1"

"1.2.840.10008.5.1.4.1.1.4.2"

"1.2.840.10008.5.1.4.1.1.5"

"1.2.840.10008.5.1.4.1.1.12.1"

"1.2.840.10008.5.1.4.1.1.12.2"

"1.2.840.10008.5.1.4.1.1.12.3"

"1.2.840.10008.5.1.4.1.1.20"

"1.2.840.10008.5.1.4.1.1.77.1.5.2"

"1.2.840.10008.5.1.4.1.1.7.3"

"1.2.840.10008.5.1.4.1.1.128"

Images32Bit

DICOM Images expected to contain up to 32 bit pixel data. Default values are:

"1.2.840.10008.5.1.4.1.1.481.2"

NonImageObjects

Persistent DICOM objects without pixel data. Default values are:

"1.2.840.10008.1.3.10"

"1.2.840.10008.5.1.1.23"

"1.2.840.10008.5.1.1.24"

"1.2.840.10008.5.1.1.26"

"1.2.840.10008.5.1.1.27"

"1.2.840.10008.5.1.1.29"

"1.2.840.10008.5.1.1.30"

"1.2.840.10008.5.1.4.1.1.8"

"1.2.840.10008.5.1.4.1.1.9"

"1.2.840.10008.5.1.4.1.1.9.1.1"

"1.2.840.10008.5.1.4.1.1.9.1.2"

"1.2.840.10008.5.1.4.1.1.9.1.3"

"1.2.840.10008.5.1.4.1.1.9.2.1"

"1.2.840.10008.5.1.4.1.1.9.3.1"

"1.2.840.10008.5.1.4.1.1.9.4.1"

"1.2.840.10008.5.1.4.1.1.10"

"1.2.840.10008.5.1.4.1.1.11"

"1.2.840.10008.5.1.4.1.1.11.1"

"1.2.840.10008.5.1.4.1.1.66"

"1.2.840.10008.5.1.4.1.1.66.1"

"1.2.840.10008.5.1.4.1.1.66.2"

"1.2.840.10008.5.1.4.1.1.77.1.5.3"

"1.2.840.10008.5.1.4.1.1.88.11"

"1.2.840.10008.5.1.4.1.1.88.22"

"1.2.840.10008.5.1.4.1.1.88.33"

"1.2.840.10008.5.1.4.1.1.88.40"

"1.2.840.10008.5.1.4.1.1.88.50"

"1.2.840.10008.5.1.4.1.1.88.59"

"1.2.840.10008.5.1.4.1.1.88.65"

"1.2.840.10008.5.1.4.1.1.104.1"

"1.2.840.10008.5.1.4.1.1.129"

"1.2.840.10008.5.1.4.1.1.481.1"

"1.2.840.10008.5.1.4.1.1.481.3"

"1.2.840.10008.5.1.4.1.1.481.4"

"1.2.840.10008.5.1.4.1.1.481.5"

"1.2.840.10008.5.1.4.1.1.481.6"

"1.2.840.10008.5.1.4.1.1.481.7"

User1, User2 & User3

Spares for unusual user-defined groupings

• Associated with each group are 3 lists:
  • A list of SOP classes to which it currently applies
  • A list of Transfer Syntaxes to be offered when initiating an association
  • A separate list of Transfer Syntaxes to be chosen (in preference order) when accepting an association

• The default lists of transfer syntaxes are as follows: