Tag: Negotiation

DICOM Extended Negotiation of User Identity

DicomObjects.NET supports extended negotation of user identity as defined in DICOM supplement 99: ftp://medical.nema.org/medical/dicom/final/sup99_ft.pdf Here is sample code for how to access this data using DicomObjects.NET SCU/Client DicomAssociation cn = new DicomAssociation(); cn.Identity = new DicomAssociation.UserIdentity(); cn.Identity.IdentityType = DicomObjects.Enums.UserIdentityType.Kerberos; cn.Identity.ResponseType = DicomObjects.Enums.UserIdentityResponseType.PositiveResponseRequested; cn.Identity.PrimaryField = new byte[] { 1, 2, 3, 4 }; // the Kerberos Service Ticket, or the username cn.RequestedContexts.Add(...); cn.Open(...); byte[] resp = cn.ServerResponse; // will be null is ResponseType is set to NoResponseRequested SCP/Server void server_AssociationRequest(object sender, DicomServer.

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Extended Negotiation

in DICOM,

Extended negotiation allows “options” to be negotiated between 2 Application Entities as part of Negotiation. In order for the option to be available for use, it must be both proposed by the initiator and agreed by the acceptor. The uses for extended negotiation are currently: Relational Queries Specification of storage level (how accurately the data is retained) for C-STORE In DicomObjects, these values are used as follows:

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Meta SOP Class

in DICOM,

A Meta SOP class is used where it is required to negotiate a “set” of SOP Classes as a batch, as one would not be useful without the others. The Meta SOP classes still used in DICOM are: BasicGrayscalePrint 1.2.840.10008.5.1.1.9.1 BasicColorPrint 1.2.840.10008.5.1.1.18.1 GeneralPurposeWorklist 1.2.840.10008.5.1.4.32 In DicomObjects, it is necessary to set the MetaSOPClass property of the DicomAssociation(.NET)/DicomConnection(COM) object explicitly when using these services, as this is the only case where the SOP class of the object being operated on does not necessarily correspond with one of the Presentation Contexts negotiated.

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Network Transfer Syntax Control (COM)

The mechanism is quite different for the simple Send methods compared to using DicomConnection DicomImage.Send / DicomDataSet.Send For these simple method, the list of offered transfer syntaxes comes from the registry, from the default value of the following key HKEY_LOCAL_MACHINE/Software/Medical Connections/DicomObjects/TransferSyntax NOTE: The above is a Key not a value. You need to edit the list of transfer syntaxes into the default value of that key. or to change dynamically, it can be controlled by

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Reverse Role Negotiation

in DICOM,

In the vast majority of Associations, the Association is initiated by the SCU with the SCP responding, but DICOM does allow Reverse Role Negotiation whereby the initiator can request to be regarded as the SCP. In practise, this is only used as part of the Storage Commitment service. An oddity of reverse role negotiation (like Extended Negotiation) is that it is agreed per SOP Class not Per Presentation Context, so an agreement to reverse the roles applies to all presentation contexts using that SOP Class.

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