Documentation Update for version 2.0.1.9

The online documentation is now updated for version 2.0.1.9. In the new documentation there's new page with information for DICOM conformance that is useful for writing the DICOM Conformance Statement.

Query/Retrieve part II - C-MOVE


In part I of this post, I was in a meeting with a customer reviewing their workstation code and while sitting there I was thinking to myself, why should my customers have to deal with so many details of the DICOM Q/R Service when all they really want is to retrieve a study just like they would have downloaded a zip file from a web site. And thus, later, back in my office I decided to extended the DICOM Toolkit API to include a C-MOVE method that will take care of everything including the incoming association. In today’s post I’m going to use the new MoveAndStore method to talk about the DICOM Query/Retrieve service. We’ll start at the end and then work our way backwards.

C-MOVE is a DICOM command that means this: The calling AE (we) ask the called AE (the PACS) to send all the DICOM Instances that match the identifier to the target AE. 
Here’s how you ask a PACS to send you the DICOM images with RZDCX (version 2.0.1.9).

        public void MoveAndStore()
        {
            // Create an object with the query matching criteria (Identifier)
            DCXOBJ query = new DCXOBJ();
            DCXELM e = new DCXELM();
            e.Init((int)DICOM_TAGS_ENUM.patientName);
            e.Value = DOE^JOHN";
            query.insertElement(e);
            e.Init((int)DICOM_TAGS_ENUM.patientID);
            e.Value = @"123456789";
query.insertElement(e);
            // Create an accepter to handle the incomming association
DCXACC accepter = new DCXACC();
            accepter.StoreDirectory = @".\MoveAndStore";
Directory.CreateDirectory(accepter.StoreDirectory);
            // Create a requester and run the query
DCXREQ requester = new DCXREQ();
            requester.MoveAndStore(
                MyAETitle, // The AE title that issue the C-MOVE
                IS_AE,     // The PACS AE title
                IS_Host,   // The PACS IP address
                IS_port,   // The PACS listener port
                MyAETitle, // The AE title to send the
                query,     // The matching criteria
                104,       // The port to receive the results
                accepter); // The accepter to handle the results
        }

Behind this rather short function hides a lot of DICOM networking and when it returns we should have all the matching objects stored in the directory “.\MoveAndStore”. Readers with some practical DICOM experience probably expect me to say that it can also fail. In that case MoveAndStore throws an exception with the error code and description. Sometimes you would have to set the detailed logging on and start reading logs like we did in chapter 5 of this tutorial on DICOM networking and in some later post we will look together at a DICOM log of a Q/R transaction.

The following diagram, taken from part 2 of the DICOM standard, is commonly seen in DICOM Conformance Statements as the Data Flow diagram of the Q/R Service. These diagrams and their notation are defined by the standard in part 2 that specify the DICOM Conformance Statement – a standard document that every application vendor should provide and that describes how they implemented the standard in their product. At some point we will get to how to read and write these documents.




The vertical dashed line represents the DICOM Protocol Interface between the two applications (it is usually a single dashed line but in this example it got a bit messed up). The arrows accros the interface represents DICOM associations. The arrow points from the application that initiates the association (the requester) to the application that responds to it (the responder or accepter). The upper part of the diagram shows the control chanel where the C-MOVE request is sent and statuses are reported back by the PACS. The lower part of the diagram shows the data chanel where the DICOM instances are sent to the client.

RZDCX 2.0.1.9

A new release of ZRDCX, 2.0.1.9, was released today. This release fixes the following issues:


#TypeStatusCreatedChangedVersionTitle 
Description
 
291codefixedJan 30Jan 30 DICOMDIR with strict = false fails on file names with .'sedit
Create filenames like 1.2.3.4.dcm ScanAndCreate(..., false) -> Exception Reported by SBX
 
290newfixedJan 19Jan 192.0.1.8MoveAndStore - Single threaded C-MOVE duplexing control and dataedit
Add a method MoveAndStore to DCXREQ to allow one command that performs both the C-MOVE and the C-STORE commands on separate but semi-synced associations.
 
287newfixedDec 12Dec 122.0.1.8Minor logging additions to RZDCXedit
Fix log messages when pres ctx id not found in store


Issue 291 addresses a very popular feature request to enable creation of DICOMDIR even when the filenames are not according to the standard. For example filenames with the instance uid like 1.2.3.4.5.6.dcm are not valid reference file id's according to the standard. Nevertheless, sometimes you would like to create a DICOMDIR file for other purposes other than exporting data on a CD. The ScanAndCreate method of DCXDICOMDIR takes a "strict" parameter that when set to false, will generate a DICOMDIR regardless of the validity of it's content (as long of course that the files are DICOM files).

Issue 290 is a new feature of RZDCX that enable to run a complete C-MOVE SCP with a single command including the incomming association. More about this feature in the upcoming chapter of the DICOM Tutorial.
Here's a short example


        public void MoveAndStore()
        {
            // Create an object with the query matching criteria (Identifier)
            DCXOBJ query = new DCXOBJ();
            DCXELM e = new DCXELM();
            e.Init((int)DICOM_TAGS_ENUM.patientName);
            e.Value = DOE^JOHN";
            query.insertElement(e);
            e.Init((int)DICOM_TAGS_ENUM.patientID);
            e.Value = @"123456789";
query.insertElement(e);
            // Create an accepter to handle the incomming association
DCXACC accepter = new DCXACC();
            accepter.StoreDirectory = @".\MoveAndStore";
Directory.CreateDirectory(accepter.StoreDirectory);
            // Create a requester and run the query
DCXREQ requester = new DCXREQ();
            requester.MoveAndStore(
                MyAETitle, // The AE title that issue the C-MOVE
                IS_AE,     // The PACS AE title
                IS_Host,   // The PACS IP address
                IS_port,   // The PACS listener port
                MyAETitle, // The AE title to send the
                query,     // The matching criteria
                104,       // The port to receive the results
                accepter); // The accepter to handle the results
        }

This single command takes care of all the details of a C-MOVE transaction. Instead of running an accepter on another thread to wait for the C-MOVE results, we pass the accepter as a parameter to the MoveAndStore method of the requester. Note that there's a new set property in DCXACC that enables setting the directory to store the incoming files. All the callbacks of DCXACC and DCXREQ can be used as well just as before.

Issue 287 is a small log enhancement that maxes it easier to to diagnose association problems. The log now shows very clearly when a presentation context for a command was not negotiated.