XNAT DICOMweb Plugin

This XNAT plugin provides a DICOMweb-compliant REST API that exposes XNAT projects as DICOMweb endpoints. This enables DICOM viewers like OHIF and VolView to connect to XNAT and browse/view DICOM data.

Features

• QIDO-RS (Query): Search for studies, series, and instances
• WADO-RS (Retrieve): Retrieve DICOM instances and metadata
• STOW-RS (Store): Upload DICOM instances to XNAT
• Full support for DICOM JSON format
• CORS enabled for web viewer integration
• XNAT authentication and authorization

Installation

1. Build the plugin:

   ./gradlew xnatPluginJar

2. Copy the generated JAR file from build/libs/ to your XNAT plugins directory:

   cp build/libs/xnat-dicomweb-plugin-1.2.0-rc1-xpl.jar /path/to/xnat/plugins/

3. Restart XNAT

Configuration

The plugin can be configured in two ways:

1. Via XNAT Admin UI (Recommended): Navigate to Administer → Plugin Settings → DICOMweb Plugin Configuration
2. Via Properties File: Add properties to {xnat-home}/config/xnat.properties or xnat-conf.properties

All configuration parameters have sensible defaults and are optional.

Pagination Settings

Control the default and maximum page sizes for QIDO-RS query responses:

Via Admin UI:

• Go to Administer → Plugin Settings → DICOMweb Plugin Configuration
• Set "Default Page Size" and "Max Page Size"

Via Properties File:

# Default page size when limit parameter is not specified (default: 100)
dicomweb.defaultPageSize=100

# Maximum allowed page size - requests exceeding this are capped (default: 1000)
dicomweb.maxPageSize=1000

Recommendations:

• Smaller page sizes (50-100): Better for slow networks or limited client memory
• Larger page sizes (200-500): Better for high-performance deployments

Multipart Upload Settings

Configure memory usage for STOW-RS (upload) operations:

Via Properties File:

# Memory threshold in bytes - files larger than this are written to disk (default: 10485760 = 10MB)
dicomweb.memoryThreshold=10485760

Recommendations:

• High memory systems (16GB+): 52428800 (50MB) for faster uploads
• Low memory systems (<8GB): 5242880 (5MB) to reduce memory pressure
• Default (10MB): Good balance for most deployments

BulkData Settings

Control when DICOM attributes use BulkDataURI references instead of inline values:

Via Properties File:

# Threshold in bytes - attributes larger than this use BulkDataURI (default: 1024 = 1KB)
dicomweb.bulkDataThreshold=1024

Recommendations:

• Smaller threshold (512-1024): More BulkDataURIs, smaller JSON responses (better for slow networks)
• Larger threshold (4096-8192): Fewer BulkDataURIs, larger JSON responses (better for fast networks)

Example Complete Configuration

Via Properties File (xnat.properties or xnat-conf.properties):

# High-performance configuration for fast network, high-memory deployment
dicomweb.defaultPageSize=200
dicomweb.maxPageSize=2000
dicomweb.memoryThreshold=52428800
dicomweb.bulkDataThreshold=4096

# Low-resource configuration for limited memory/network
dicomweb.defaultPageSize=50
dicomweb.maxPageSize=500
dicomweb.memoryThreshold=5242880
dicomweb.bulkDataThreshold=512

Note: Changes via the Admin UI take effect immediately. Changes to properties files require an XNAT restart.

API Endpoints

All endpoints are prefixed with /xapi/dicomweb/projects/{projectId}

QIDO-RS (Query) Endpoints

• Search Studies: GET /xapi/dicomweb/projects/{projectId}/studies

  • Returns all studies (imaging sessions) in the project

• Search Series: GET /xapi/dicomweb/projects/{projectId}/studies/{studyUID}/series

  • Returns all series (scans) in a study

• Search Instances: GET /xapi/dicomweb/projects/{projectId}/studies/{studyUID}/series/{seriesUID}/instances

  • Returns all instances in a series

WADO-RS (Retrieve) Endpoints

• Retrieve Instance: GET /xapi/dicomweb/projects/{projectId}/studies/{studyUID}/series/{seriesUID}/instances/{instanceUID}

  • Returns a single DICOM instance

• Retrieve Instance Metadata: GET /xapi/dicomweb/projects/{projectId}/studies/{studyUID}/series/{seriesUID}/instances/{instanceUID}/metadata

  • Returns metadata for a single instance in JSON format

• Retrieve Series: GET /xapi/dicomweb/projects/{projectId}/studies/{studyUID}/series/{seriesUID}

  • Returns all instances in a series as multipart/related

• Retrieve Study Metadata: GET /xapi/dicomweb/projects/{projectId}/studies/{studyUID}/metadata

  • Returns comprehensive study-level metadata including series/instance counts

• Retrieve Series Metadata: GET /xapi/dicomweb/projects/{projectId}/studies/{studyUID}/series/{seriesUID}/metadata

  • Returns metadata for all instances in a series

• Retrieve Study: GET /xapi/dicomweb/projects/{projectId}/studies/{studyUID}

  • Returns all instances in a study as multipart/related

• Retrieve Rendered Instance: GET /xapi/dicomweb/projects/{projectId}/studies/{studyUID}/series/{seriesUID}/instances/{instanceUID}/rendered

  • Returns a rendered JPEG image of the instance

STOW-RS (Store) Endpoints

• Store Instances: POST /xapi/dicomweb/projects/{projectId}/studies?strategy={strategyName}
  • Upload DICOM instances via multipart/related request
  • Requires Edit permission on the project
  • Validates project exists before processing
  • Returns STOW-RS response with success/failure status per instance
  • Strategy Parameter (optional):
    • GradualDicomImporter (default) - Uses XNAT's standard import pipeline with full validation
    • DirectWrite - Direct write to prearchive with automatic session registration via PrearcDatabase API
    • Both strategies support automatic session registration and archiving

Using with OHIF Viewer

1. Configure OHIF to use the DICOMweb endpoint:

window.config = {
  routerBasename: '/',
  servers: {
    dicomWeb: [
      {
        name: 'XNAT',
        wadoUriRoot: 'https://your-xnat-server/xapi/dicomweb/projects/YOUR_PROJECT',
        qidoRoot: 'https://your-xnat-server/xapi/dicomweb/projects/YOUR_PROJECT',
        wadoRoot: 'https://your-xnat-server/xapi/dicomweb/projects/YOUR_PROJECT',
        qidoSupportsIncludeField: false,
        imageRendering: 'wadors',
        thumbnailRendering: 'wadors',
      },
    ],
  },
};

2. Access OHIF with your XNAT credentials

Using with VolView

1. In VolView, go to File > Remote
2. Enter the DICOMweb URL: https://your-xnat-server/xapi/dicomweb/projects/YOUR_PROJECT
3. Authenticate with your XNAT credentials
4. Browse and load studies

Authentication

The plugin uses XNAT's built-in authentication. Users must be authenticated with XNAT and have appropriate permissions to access the project.

Requirements

• XNAT 1.9.0 or higher (implemented for 1.9.x)
• Java 8 or higher
• DICOM data stored in XNAT with proper StudyInstanceUID, SeriesInstanceUID, and SOPInstanceUID
• XNAT archive path (defaults to /data/xnat/archive, configurable via xnat.archive system property)

Architecture

The plugin consists of:

• DicomWebPlugin: Main plugin class
• DicomWebConfig: Spring configuration and CORS setup
• QidoRsApi: REST controller for QIDO-RS queries
• WadoRsApi: REST controller for WADO-RS retrieval
• StowRsApi: REST controller for STOW-RS storage
• XnatDicomService/XnatDicomServiceImpl: Service layer for accessing XNAT data
• DicomWebUtils: Utility methods for DICOM/JSON conversion
• DicomWebTestPageApi: Test page endpoint for validation

Development

Build the plugin:

./gradlew build

Run tests:

./gradlew test

License

This plugin follows the same license as XNAT.

Support

For issues and feature requests, please use the project's issue tracker.