CTP Configuration for the Image Sharing Project

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This article describes how the CTP application can be configured for use in the RSNA Image Sharing Project. This article is intended for Image Sharing Project developers. There are several CTP articles on the RSNA MIRC wiki. All would be useful references when reading this article.

The Image Sharing Project is separated into two main use cases, one for the transfer of images for clinical use and one for transfer of anonymized research data. Each use case has a sender and a receiver.

• The clinical sender is completely contained in the Edge Server and does not involve CTP.
• The clinical receiver has two alternative configurations, one using both the Edge Server and CTP and the other using CTP stand-alone.
• The research sender uses both the Edge Server and CTP together.
• The research receiver uses CTP stand-alone.

The configuration of a CTP instance is specified by an XML file called config.xml. See CTP-The RSNA Clinical Trial Processor for detailed information about pipelines, pipeline stages, plugins, and the general processing model of the program.

This article presents separate configuration file examples for each of the use cases, but it should be understood that the configurations can be combined when multiple use cases are served by the same CTP instance.

In all the configurations shown below, the server is put on port 80, and SSL is not enabled for access to the server itself, although communication with the Clearinghouse is always secure.

1 Configuration File for the Research Sender

The configuration shown below assumes that unanonymized DICOM data objects are transmitted to CTP by an external application using the DICOM protocol. The objects are anonymized, removing PHI from both the text elements and the pixels. The objects are then cached until a user manually selects the study and assigns a destination, after which they are exported to the clearing house.

In this configuration, all the stages except the CachingXDSExportService are standard CTP stages. They are all documented in CTP-The RSNA Clinical Trial Processor.

Note: The DicomDecompressor and DicomPixelAnonymizer stages in this configuration can be removed if PHI is known not to be burned into the pixels. If the DicomPixelAnonymizer is in the pipeline, the DicomDecompressor must also be present, and it must appear in the sequence shown below.

<Configuration>

   <Server port="80" />

   <Pipeline name="Research Sender Pipeline">

        <DicomImportService
            name="DicomImportService-RS"
            class="org.rsna.ctp.stdstages.DicomImportService"
            root="roots/DicomImportService-RS" 
            port="104"
            calledAETTag="00097770" 
            callingAETTag="00097772"
            logConnections="no"
            suppressDuplicates="no"
            quarantine="quarantines/DicomImportService-RS" />

        <ObjectCache
            name="ObjectCache-RS"
            class="org.rsna.ctp.stdstages.ObjectCache"
            id="ObjectCache-RS"
            root="roots/ObjectCache-RS" />

        <DicomAnonymizer
            name="DicomAnonymizer-RS"
            class="org.rsna.ctp.stdstages.DicomAnonymizer"
            root="roots/DicomAnonymizer-RS" 
            lookupTable="scripts/lookup-table.properties"
            script="scripts/dicom-anonymizer.script"
            quarantine="quarantines/DicomAnonymizer-RS" />

        <DicomDecompressor
            name="DicomDecompressor-RS"
            class="org.rsna.ctp.stdstages.DicomDecompressor"
            root="roots/DicomDecompressor-RS" 
            quarantine="quarantines/DicomDecompressor-RS" />

        <DicomPixelAnonymizer
            name="DicomPixelAnonymizer-RS"
            class="org.rsna.ctp.stdstages.DicomPixelAnonymizer"
            root="roots/DicomPixelAnonymizer-RS" 
            script="scripts/DicomPixelAnonymizer.script"
            quarantine="quarantines/DicomPixelAnonymizer-RS" />

        <CachingXDSExportService
            name="CachingXDSExportService-RS"
            class="org.rsna.isn.ctp.xds.sender.CachingXDSExportService"
            root="roots/CachingXDSExportService-RS"
            cacheID="ObjectCache-RS"
            servletContext="researchsender"
            minAge="300"
            timeDepth="30"

            ...more attributes, once we know what they are...

            quarantine="quarantines/CachingXDSExportService-RS" />

    </Pipeline>

</Configuration>

1.1 CachingXDSExportService

The special attributes of the CachingXDSExportService are:

• root is a directory within which the CachingXDSExportService caches objects and stores its indexing information.
• cacheID specifies the ID of an ObjectCache stage that may be accessed by the CachingXDSExportService to obtain pre-anonyization information so it can index the objects by their PHI and make that information available to a user who accesses the servlet. If the cacheID attribute is not supplied, the CachingXDSExportService indexes the objects by the anonymized values.
• servletContext specifies the context of a servlet that provides a user interface allowing as user to select cached studies and assign them destinations for export. The purpose of the servletContext attribute is to allow each CachingXDSExportService to have its own servlet in cases where multiple export pipelines are present in the same CTP instance.
• minAge is the minimum age in seconds which defines the completion of a study. When the last object received for a study is at least minAge old, the study is considered complete and is available for selection for export. The default value is 300; the minimum accepted value is 60.
• timeDepth specifies the length of time in days that studies are stored. The default value is 0, which means forever. If timeDepth is greater than zero, studies older than that value are automatically removed from the cache, making them no longer available for export.

1.2 CachingXDSExportService Servlet API

The servlet provided by the CachingXDSExportService is installed on the CTP servlet container at the context specified by the servletContext attribute. The servlet provides the following APIs:

• /{servletContext} - GET returns an HTML page containing a form for selection of studies and destinations.
• /{servletContext} - POST accepts a completed form and returns a new HTML page.

• /{servletContext}/ES - GET returns an HTML page like the one above, but with styles consistent with those of the Edge Server.
• /{servletContext}/ES - POST accepts a completed form and returns a new HTML page.

• /{servletContext}/status - returns an XML structure encapsulating the status of all studies in the cache.
• /{servletContext}/status?study={StudyInstanceUID} - returns an XML structure encapsulating the status of the specified study.

A status response is returned with Content-Type: text/xml;charset=UTF-8. The schema is in the form:

<Status>

	<Study
		status="incomplete|complete|intransit"
		size="number of cached objects"
		destination="..."
		patientName="..."
		patientID="..."
		studyInstanceUID="..."
		noOfObjectsSent="n"/>
		
	...more <Study> elements as necessary...
	
</Status>

2 Configuration File for the Research Receiver

The configuration shown below polls the Clearinghouse for submission sets, imports them, and passes the objects down the pipe.

<Configuration>

   <Server port="80" />

   <Pipeline name="Research Receiver Pipeline">

        <PollingXDSImportService
            name="PollingXDSImportService-RR"
            class="org.rsna.isp.PollingXDSImportService"
            root="roots/PollingXDSImportService-RR" 
            interval="300"
            
            rad69URL="..."
            registryURL="..."
            repositoryURL="..."
            repositoryUniqueID="..."
            assigningAuthorityUniversalId="..."
            assigningAuthorityUniversalIdType="..."
            
            homeCommunityId="..."
            
            keystore="..."
            keystorepassword="..."
            truststore="..."
            truststorepassword="..."
            
            siteID="..."
            servletContext="xds" />

        <DicomExportService
            name="DicomExportService-RR"
            class="org.rsna.ctp.stdstages.DicomExportService"
            root="roots/DicomExportService-RR" 
            quarantine="quarantines/DicomExportService-RR"
            url="dicom://DestinationAET:ThisAET@ipaddress:port" />

    </Pipeline>

</Configuration>

2.1 PollingXDSImportService

The special attributes of the PollingXDSImportService are:

• root is a directory within which the PollingXDSImportService stores its import queue.
• interval specifies the sleep time in seconds between polls of the Clearinghouse.
• siteID specifies the key or keys on which to poll the Clearinghouse. See the notes below for details.
• servletContext specifies the context of a servlet that provides a user interface allowing a user to manually enter a key to import a submission set. The purpose of the servletContext attribute is to allow each PollingXDSImportService to have its own servlet in cases where multiple import pipelines are present in the same CTP instance.

Notes:

• The siteID can be specified as either a single key or a series of keys separated by semicolons.
• The PollingXDSImportService polls on each key in turn, importing all the submission sets that are available. It then sleeps for the specified interval and then polls again.
• All submission sets imported by a single PollingXDSImportService will flow down its pipe, so unless two clinical trials are sending their data to the same DICOM destination, it is best to put each trial in its own pipe, giving each PollingXDSImportService only a single key.