REST API of Orthanc

One of the major strengths of Orthanc lies in its built-in RESTful API, that can be used to drive Orthanc from external applications, independently of the programming language that is used to develop these applications. The REST API of Orthanc gives a full programmatic access to all the core features of Orthanc.

Importantly, Orthanc Explorer (the embedded administrative interface of Orthanc) entirely resorts to this REST API for all its features. This implies that anything that can be done through Orthanc Explorer, can also be done through REST queries.

Note: All the examples are illustrated with the cURL command-line tool, but equivalent calls can be readily transposed to any programming language that supports both HTTP and JSON.

Warning about using cURL from the Windows prompt

The examples on this page assume that the user is running a bash shell on some GNU/Linux distribution. Such a shell has the major advantage of having the possibility to use either single-quote or double-quotes characters in order to group a set of characters (including spaces) as a whole string.

Unfortunately, the default command-line prompt of Microsoft Windows doesn’t support single-quote characters. If you copy/paste a cURL command-line from this page that mixes single-quote and double-quotes, it won’t work as such, and you’ll have to replace single-quotes by double-quotes, and prefix the double-quotes by a backslash character. For instance, consider the following command line that works fine on GNU/Linux:

$ curl -v -X PUT http://localhost:8042/modalities/sample \
       -d '{"AET" : "ORTHANCC", "Host": "", "Port": 2002}'

This call will not work on the Microsoft Windows prompt as it contains single-quotes. You should adapt this command line as follows to run it on Windows:

$ curl -v -X PUT http://localhost:8042/modalities/sample \
       -d "{\"AET\" : \"ORTHANCC\", \"Host\": \"\", \"Port\": 2002}"

As an alternative, consider using a different Windows shell, for instance Windows PowerShell (some examples of PowerShell can be found below on this page).

Sending DICOM images

The upload of DICOM files is possible by querying the REST API using the following syntax:

$ curl -X POST http://localhost:8042/instances --data-binary @CT.X.
$ curl -X POST http://localhost:8042/instances --data-binary

Orthanc will respond with a JSON file that contain information about the location of the stored instance, such as:

  "ID" : "5d4a3991-8a265cb2-da669bea-d8c761af-4a77113a",
  "ParentPatient" : "69a957ab-57545037-ce9a492a-d0bd89c1-d7e2220d",
  "ParentSeries" : "87c81b2c-e9f92adf-2dc11d37-399b5214-37275cdb",
  "ParentStudy" : "1b1cc0c9-c0377071-78e8cd3a-2e382948-a243db42",
  "Path" : "/instances/5d4a3991-8a265cb2-da669bea-d8c761af-4a77113a",
  "Status" : "Success"

Note that in the case of curl, setting the Expect HTTP Header will significantly reduce the execution time of POST requests:

$ curl -X POST -H "Expect:" http://localhost:8042/instances --data-binary @CT.X.

The code distribution of Orthanc contains a sample Python script that recursively upload the content of some folder into Orthanc using the REST API:

$ python localhost 8042 ~/DICOM/

Starting with Orthanc 1.8.1, the source distribution of Orthanc includes another Python script named that provides more features than It can notably import the content of .zip, .tar.gz or .tar.bz2 archives without having to uncompress them first. It also provides more comprehensive command-line options. Check this script out.

If you are using Powershell (>= 3.0), you can use the following to send a single Dicom instance to Orthanc:

# disabling the progress bar makes the Invoke-RestMethod call MUCH faster
$ProgressPreference = 'SilentlyContinue'

# upload it to Orthanc
$reply = Invoke-RestMethod http://localhost:8042/instances -Method POST -InFile CT.X.

# display the result
Write-Host "The instance can be retrieved at http://localhost:8042$($reply.Path)"

Accessing the content of Orthanc

Orthanc structures the stored DICOM resources using the “Patient, Study, Series, Instance” model of the DICOM standard. Each DICOM resource is associated with an unique identifier.

List all the DICOM resources

Here is how you would list all the DICOM resources that are stored in your local Orthanc instance:

$ curl http://localhost:8042/patients
$ curl http://localhost:8042/studies
$ curl http://localhost:8042/series
$ curl http://localhost:8042/instances

Note that the result of this command is a JSON file that contains an array of resource identifiers. The JSON file format is lightweight and can be parsed from almost any computer language.

Accessing a patient

To access a single resource, add its identifier to the URI. You would for instance retrieve the main information about one patient as follows:

$ curl http://localhost:8042/patients/dc65762c-f476e8b9-898834f4-2f8a5014-2599bc94

Here is a possible answer from Orthanc:

  "ID" : "07a6ec1c-1be5920b-18ef5358-d24441f3-10e926ea",
  "MainDicomTags" : {
     "OtherPatientIDs" : "(null)",
     "PatientBirthDate" : "0",
     "PatientID" : "000000185",
     "PatientName" : "Anonymous^Unknown",
     "PatientSex" : "O"
  "Studies" : [ "9ad2b0da-a406c43c-6e0df76d-1204b86f-78d12c15" ],
  "Type" : "Patient"

This is once again a JSON file. Note how Orthanc gives you a summary of the main DICOM tags that correspond to the patient level.

Browsing from the patient down to the instance

The field Studies list all the DICOM studies that are associated with the patient. So, considering the patient above, we would go down in her DICOM hierarchy as follows:

$ curl http://localhost:8042/studies/9ad2b0da-a406c43c-6e0df76d-1204b86f-78d12c15

And Orthanc could answer:

  "ID" : "9ad2b0da-a406c43c-6e0df76d-1204b86f-78d12c15",
  "MainDicomTags" : {
     "AccessionNumber" : "(null)",
     "StudyDate" : "20120716",
     "StudyDescription" : "TestSUVce-TF",
     "StudyID" : "23848",
     "StudyInstanceUID" : "1.2.840.113704.1.111.7016.1342451220.40",
     "StudyTime" : "170728"
  "ParentPatient" : "07a6ec1c-1be5920b-18ef5358-d24441f3-10e926ea",
  "Series" : [
  "Type" : "Study"

The main DICOM tags are now those that are related to the study level. It is possible to retrieve the identifier of the patient in the ParentPatient field, which can be used to go upward the DICOM hierarchy. But let us rather go down to the series level by using the Series array. The next command would return information about one of the three series that have just been reported:

$ curl http://localhost:8042/series/2cc6336f-2d4ae733-537b3ca3-e98184b1-ba494b35

Here is a possible answer:

  "ExpectedNumberOfInstances" : 45,
  "ID" : "2cc6336f-2d4ae733-537b3ca3-e98184b1-ba494b35",
  "Instances" : [
  "MainDicomTags" : {
     "Manufacturer" : "Philips Medical Systems",
     "Modality" : "PT",
     "NumberOfSlices" : "45",
     "ProtocolName" : "CHU/Body_PET/CT___50",
     "SeriesDate" : "20120716",
     "SeriesDescription" : "[WB_CTAC] Body",
     "SeriesInstanceUID" : "",
     "SeriesNumber" : "587370",
     "SeriesTime" : "171121",
     "StationName" : "r054-svr"
  "ParentStudy" : "9ad2b0da-a406c43c-6e0df76d-1204b86f-78d12c15",
  "Status" : "Complete",
  "Type" : "Series"

It can be seen that this series comes from a PET modality. Orthanc has computed that this series should contain 45 instances.

So far, we have navigated from the patient level, to the study level, and finally to the series level. There only remains the instance level. Let us dump the content of one of the instances:

$ curl http://localhost:8042/instances/e668dcbf-8829a100-c0bd203b-41e404d9-c533f3d4

The instance contains the following information:

  "FileSize" : 70356,
  "FileUuid" : "3fd265f0-c2b6-41a2-ace8-ae332db63e06",
  "ID" : "e668dcbf-8829a100-c0bd203b-41e404d9-c533f3d4",
  "IndexInSeries" : 6,
  "MainDicomTags" : {
     "ImageIndex" : "6",
     "InstanceCreationDate" : "20120716",
     "InstanceCreationTime" : "171344",
     "InstanceNumber" : "6",
     "SOPInstanceUID" : ""
  "ParentSeries" : "2cc6336f-2d4ae733-537b3ca3-e98184b1-ba494b35",
  "Type" : "Instance"

The instance has the index 6 in the parent series. The instance is stored as a raw DICOM file of 70356 bytes. You would download this DICOM file using the following command:

$ curl http://localhost:8042/instances/e668dcbf-8829a100-c0bd203b-41e404d9-c533f3d4/file > Instance.dcm

Accessing the DICOM fields of an instance as a JSON file

When one gets to the instance level, you can retrieve the hierarchy of all the DICOM tags of this instance as a JSON file:

$ curl http://localhost:8042/instances/e668dcbf-8829a100-c0bd203b-41e404d9-c533f3d4/simplified-tags

Here is a excerpt of the Orthanc answer:

  "ACR_NEMA_2C_VariablePixelDataGroupLength" : "57130",
  "AccessionNumber" : null,
  "AcquisitionDate" : "20120716",
  "AcquisitionDateTime" : "20120716171219",
  "AcquisitionTime" : "171219",
  "ActualFrameDuration" : "3597793",
  "AttenuationCorrectionMethod" : "CTAC-SG",
  "PatientID" : "000000185",
  "PatientName" : "Anonymous^Unknown",
  "PatientOrientationCodeSequence" : [
        "CodeMeaning" : "recumbent",
        "CodeValue" : "F-10450",
        "CodingSchemeDesignator" : "99SDM",
        "PatientOrientationModifierCodeSequence" : [
              "CodeMeaning" : "supine",
              "CodeValue" : "F-10340",
              "CodingSchemeDesignator" : "99SDM"
  "StudyDescription" : "TestSUVce-TF",
  "StudyID" : "23848",
  "StudyInstanceUID" : "1.2.840.113704.1.111.7016.1342451220.40",
  "StudyTime" : "171117",
  "TypeOfDetectorMotion" : "NONE",
  "Units" : "BQML",
  "Unknown" : null,
  "WindowCenter" : "1.496995e+04",
  "WindowWidth" : "2.993990e+04"

If you need more detailed information about the type of the variables or if you wish to use the hexadecimal indexes of DICOM tags, you are free to use the following URL:

$ curl http://localhost:8042/instances/e668dcbf-8829a100-c0bd203b-41e404d9-c533f3d4/tags

Accessing the raw DICOM fields of an instance

You also have the opportunity to access the raw value of the DICOM tags of an instance, without going through a JSON file. Here is how you would find the Patient Name of the instance:

$ curl http://localhost:8042/instances/e668dcbf-8829a100-c0bd203b-41e404d9-c533f3d4/content/0010-0010

The list of all the available tags for this instance can also be retrieved easily:

$ curl http://localhost:8042/instances/e668dcbf-8829a100-c0bd203b-41e404d9-c533f3d4/content

It is also possible to recursively explore the sequences of tags:

$ curl http://localhost:8042/instances/e668dcbf-8829a100-c0bd203b-41e404d9-c533f3d4/content/0008-1250/0/0040-a170/0/0008-0104
For Attenuation Correction

The command above has opened the “0008-1250” tag that is a DICOM sequence, taken its first child, opened its “0040-a170” tag that is also a sequence, taken the first child of this child, and returned the “0008-0104” DICOM tag.

Downloading images

As explained above, the raw DICOM file corresponding to a single instance can be retrieved as follows:

$ curl http://localhost:8042/instances/609665c0-c5198aa2-8632476b-a00e0de0-e9075d94/file > Instance.dcm

It is also possible to download a preview PNG image that corresponds to some DICOM instance:

$ curl http://localhost:8042/instances/609665c0-c5198aa2-8632476b-a00e0de0-e9075d94/preview > Preview.png

The resulting image will be a standard graylevel PNG image (with 8 bits per pixel) that can be opened by any painting software. The dynamic range of the pixel data is stretched to the [0..255] range. An equivalent JPEG image can be downloaded by setting the HTTP header Accept to image/jpeg. By default, the jpeg quality is set to 90% but this can be specified in the url:

$ curl -H 'Accept: image/jpeg' http://localhost:8042/instances/609665c0-c5198aa2-8632476b-a00e0de0-e9075d94/preview > Preview.jpg
$ curl -H 'Accept: image/jpeg' http://localhost:8042/instances/609665c0-c5198aa2-8632476b-a00e0de0-e9075d94/preview?quality=80 > Preview80.jpg

If you don’t want to stretch the dynamic range, and create a 8bpp or 16bpp PNG image, you can use the following URIs:

$ curl http://localhost:8042/instances/609665c0-c5198aa2-8632476b-a00e0de0-e9075d94/image-uint8 > full-8.png
$ curl http://localhost:8042/instances/609665c0-c5198aa2-8632476b-a00e0de0-e9075d94/image-uint16 > full-16.png

In these images, the values are cropped to the maximal value that can be encoded by the target image format. The /instances/{...}/image-int16 is available as well to download signed DICOM pixel data.

Since Orthanc 1.4.2, it is also possible to download such images in the generic PAM format:

$ curl -H 'Accept: image/x-portable-arbitrarymap' http://localhost:8042/instances/609665c0-c5198aa2-8632476b-a00e0de0-e9075d94/image-uint16 > full-16.pam

Users of Matlab or Octave can find related information in the dedicated section.

Downloading decoded images from Python

Starting with Orthanc 1.11.0, it is possible to immediately download DICOM instances and DICOM series as numpy arrays (even if they use a compressed transfer syntax). This is especially useful for the integration within AI (artificial intelligence) pipelines. Here is a sample call:

import io
import numpy
import requests

r = requests.get('')

image = numpy.load(io.BytesIO(r.content))
print(image.shape)  # (1, 358, 512, 1)

The downloaded numpy array for one single DICOM instance contains floating-point values, and has a shape of (1, height, width, 1) if the corresponding instance is grayscale, or (1, height, width, 3) if the instance has colors (e.g. in ultrasound images). If applicable, the Rescale Slope (0028,1053) and Rescale Intercept (0028,1052) DICOM tags are applied to the floating-point values.

Similarly, this feature is available at the series level:

import io
import numpy
import requests

r = requests.get('')

image = numpy.load(io.BytesIO(r.content))
print(image.shape)  # (100, 256, 256, 1)

As can be seen, in the case of a DICOM series, the first dimension of the resulting numpy array corresponds to the depth of the series (i.e. to its number of 2D slices).

Some options are available for these /instances/.../numpy and /series/.../numpy routes:

  • ?compress=1 will return a .npz compressed numpy archive instead of a plain .npy numpy array. This can be used to reduce the network bandwidth. In such a case, the array of interest is named arr_0 in the .npz archive, e.g.:

  • ?rescale=0 will skip the conversion to floating-point values, and will not apply the rescale slope/intercept. This can be useful to reduce the network bandwidth or to receive the original integer values of the voxels.

Downloading studies

All instances of a study can be retrieved as a zip file as follows:

$ curl http://localhost:8042/studies/6b9e19d9-62094390-5f9ddb01-4a191ae7-9766b715/archive >

It is also possible to download a zipped DICOMDIR through:

$ curl http://localhost:8042/studies/6b9e19d9-62094390-5f9ddb01-4a191ae7-9766b715/media >

Downloading PDF or videos

Given a DICOM instance that embeds a PDF file (typically, one instance whose SOP Class UID is 1.2.840.10008. - Encapsulated PDF Storage), the PDF content can be downloaded as follows:

$ curl http://localhost:8042/instances/1915e0cc-c2c1a0fc-12cdd7f5-3ba32114-a97c2c9b/content/0042,0011 > sample.pdf

This corresponds to downloading the raw DICOM tag “Encapsulated Document” (0042,0011). Beware that the last byte of the downloaded file might correspond to one padding byte, if the source PDF had an odd number of bytes.

Similarly, if you know that a DICOM instance embeds a video (which can be tested by checking the value of the metadata corresponding to its transfer syntax UID), the raw video can be downloaded as follows:

$ curl http://localhost:8042/instances/e465dd27-83c96343-96848735-7035a133-1facf1a0/frames/0/raw > sample.mp4

Sending resources to remote Orthanc over HTTP/HTTPS (through Orthanc peering)

Orthanc can send its DICOM instances to remote Orthanc servers over HTTP/HTTPS. Such servers are referred to as Orthanc peers. This process can be triggered by the REST API, which is described in this section.


You first have to declare the Url of the remote orthanc inside the configuration file. For instance, here is how to declare a remote orthanc peer:

"OrthancPeers" : {
  "sample" : [ "http://localhost:8043" ], // short version
  "sample2" : {                           // long version
    "Url" : "http://localhost:8044",
    "Username" : "alice",                          // optional
    "Password" : "alicePassword",                  // optional
    "HttpHeaders" : { "Token" : "Hello world" },   // optional
    "CertificateFile" : "client.crt",              // optional (only if using client certificate authentication)
    "CertificateKeyFile" : "client.key",           // optional (only if using client certificate authentication)
    "CertificateKeyPassword" : "certpass"          // optional (only if using client certificate authentication)

Such a configuration would enable Orthanc to connect to two other Orthanc instances that listens on the localhost on the ports 8043 and 8044. The peers that are known to Orthanc can be queried:

$ curl http://localhost:8042/peers?expand

Instead of using the configuration file, peers can be created or updated through the REST API using the PUT method of HTTP:

$ curl -v -X PUT http://localhost:8042/peers/sample -d '{"Url" : ""}'

One peer can also be removed using the DELETE method as follows:

$ curl -v -X DELETE http://localhost:8042/peers/sample

Note that, by default, peers are read from the Orthanc configuration files and are updated in Orthanc memory only. If you want your modifications to be persistent, you should configure Orthanc to store its peers in the database. This is done through this configuration:

"OrthancPeersInDatabase" : true,

Sending One Resource

Once you have identified the Orthanc identifier of the DICOM resource that would like to send as explained above, you would use the following command to send it:

$ curl -X POST http://localhost:8042/peers/sample/store -d c4ec7f68-9b162055-2c8c5888-5bf5752f-155ab19f

The /sample/ component of the URI corresponds to the identifier of the remote modality, as specified above in the configuration file.

Note that you can send isolated DICOM instances with this command, but also entire patients, studies or series. It is possible to send multiple instances with a single POST request:

$ curl -X POST http://localhost:8042/peers/sample/store -d '["d4b46c8e-74b16992-b0f5ca11-f04a60fa-8eb13a88","d5604121-7d613ce6-c315a5-a77b3cf3-9c253b23","cb855110-5f4da420-ec9dc9cb-2af6a9bb-dcbd180e"]'

Note that the list of resources to be sent can include the Orthanc identifiers of entire patients, studies or series as well.

Important remark: Neither the metadata, nor the attachments are transferred between the Orthanc peers. This is because metadata and attachments are considered as local to one Orthanc server.

Testing connectivity with a remote peer

In version 1.5.9+, we have introduced a route to retrieve the /system info from a remote peer. This route can also be used to test the connectivity with that peer without actually sending a DICOM resource.:

$ curl http://localhost:8042/peers/sample/system


If you’re transfering medical data over internet, it is mandatory to use HTTPS.

On the server side, we recommend to put Orthanc behind an HTTPS server that will take care of the TLS.

On the client side, in order for the client Orthanc to recognize the server certificate, you’ll have to provide a path to the CA (certification authority) certificates. This is done in the configuration file through this configurationg:

"HttpsCACertificates" : "/etc/ssl/certs/ca-certificates.crt,

If you want your server to accept incoming connections for known hosts only, you can either:

  • configure a firewall to accept incoming connections from known IP addresses

  • configure your client Orthanc to use a client certificate to authenticate at the Server. This is done through the CertificateFile, CertificateKeyFile and CertificateKeyPassword entries in the configuration file.

Sending resources to remote modalities (through DICOM C-Store)

Orthanc can send its DICOM instances to remote DICOM modalities (C-Store SCU). This process can be triggered by the REST API.


You first have to declare the AET, the IP address and the port number of the remote modality inside the configuration file. For instance, here is how to declare a remote modality:

"DicomModalities" : {
  "sample" : [ "ORTHANCA", "", 2000 ], // short version
  "sample2" : {                                 // long version
    "AET" : "ORTHANCB",
    "Port" : 2001,
    "Host" : "",
    "Manufacturer" : "Generic",
    "AllowEcho" : true,
    "AllowFind" : true,
    "AllowMove" : true,
    "AllowStore" : true

Such a configuration would enable Orthanc to connect to two DICOM stores (for instance, other Orthanc instances) that listens on the localhost on the port 2000 & 2001. The modalities that are known to Orthanc can be queried:

$ curl http://localhost:8042/modalities?expand

Instead of using the configuration file, modalities can be created or updated through the REST API using the PUT method of HTTP:

$ curl -v -X PUT http://localhost:8042/modalities/sample -d '{"AET" : "ORTHANCC", "Host": "", "Port": 2002}'

One modality can also be removed using the DELETE method as follows:

$ curl -v -X DELETE http://localhost:8042/modalities/sample

Note that, by default, modalities are read from the Orthanc configuration files and are updated in Orthanc memory only. If you want your modifications to be persistent, you should configure Orthanc to store the modalities in the database. This is done through this configuration:

"DicomModalitiesInDatabase" : true,

Sending One Resource

Once you have identified the Orthanc identifier of the DICOM resource that would like to send as explained above, you would use the following command to send it:

$ curl -X POST http://localhost:8042/modalities/sample/store -d c4ec7f68-9b162055-2c8c5888-5bf5752f-155ab19f

The /sample/ component of the URI corresponds to the identifier of the remote modality, as specified above in the configuration file.

Note that you can send isolated DICOM instances with this command, but also entire patients, studies or series.

Various optional fields are also available. i.e, if you need to monitor the state of a transfer, you can start the transfer in asynchronous mode, which will provide you with the identifier of the Orthanc job:

$ curl -X POST http://localhost:8042/modalities/sample/store \
  --data '{
            "Resources" : ["d4b46c8e-74b16992-b0f5ca11-f04a60fa-8eb13a88"],
            "Synchronous" : false,
            "LocalAet" : "ORTHANC",
            "MoveOriginatorAet": "ORTHANC",
            "MoveOriginatorID": 1234,
            "Timeout": 10,
            "StorageCommitment": false

Bulk Store SCU

Each time a POST request is made to /modalities/.../store, a new DICOM association is possibly established. This may lead to a large communication overhead if sending multiple isolated instances by making one REST call for each of these instances.

To circumvent this problem, you have 2 possibilities:

  1. Set the DicomAssociationCloseDelay option in the configuration file to a non-zero value. This will keep the DICOM connection open for a certain amount of time, waiting for new instances to be routed. This is useful if autorouting images using Lua.

  2. It is possible to send multiple instances with a single POST request (so-called “Bulk Store SCU”, available from Orthanc 0.5.2):

    $ curl -X POST http://localhost:8042/modalities/sample/store -d '["d4b46c8e-74b16992-b0f5ca11-f04a60fa-8eb13a88","d5604121-7d613ce6-c315a5-a77b3cf3-9c253b23","cb855110-5f4da420-ec9dc9cb-2af6a9bb-dcbd180e"]'

    The list of the resources to be sent are given as a JSON array. In this case, a single DICOM connection is used. Sample code is available.

    Note that the list of resources to be sent can include the Orthanc identifiers of entire patients, studies or series as well.

Performing C-Echo

To validate the DICOM connectivity between Orthanc and a remote modality, you can perform a C-ECHO:

$ curl -X POST http://localhost:8042/modalities/sample/echo -d '{}'

From Orthanc 1.7.0, you can include an extra Timeout field:

$ curl -X POST http://localhost:8042/modalities/sample/echo -d '{ "Timeout": 10 }'

If no Timeout parameter is specified, the value of the DicomScuTimeout configuration is used as a default. If Timeout is set to zero, this means no timeout.

NB: A body containing a valid JSON object is needed by /modalities/{id}/echo since Orthanc 1.7.0.

Performing C-Move

You can perform a DICOM C-Move to move a specific study from one modality to another (including Orthanc itself if you don’t specify the TargetAet field).

I.e. to move a study whose you know the StudyInstanceUID from the modality sample to another Orthanc whose AET is ORTHANCB:

$ curl --request POST --url http://localhost:8042/modalities/samples/move \
  --data '{
            "Level" : "Study",
            "Resources" : [
                "StudyInstanceUID": "1.2.840.113543."
            "TargetAet": "ORTHANCB",
            "Timeout": 60

Performing Query/Retrieve (C-Find) and Find with REST

Section contributed by Bryan Dearlove

Orthanc can be used to perform queries on the local Orthanc instance, or on remote modalities through the REST API.

To perform a query of a remote modality you must define the modality within the configuration file (See Configuration section under Sending resources to remote modalities).

Performing Queries on Modalities

To initiate a query you perform a POST command against the Modality with the identifiers you are looking for. The the example below we are performing a study level query against the modality sample for any study descriptions with the word chest within it. This search is case insensitive unless configured otherwise within the Orthanc configuration file:

$ curl --request POST \
  --url http://localhost:8042/modalities/sample/query \
  --data '{
            "Level" : "Study",
            "Query" : {
              "PatientID" : "",
              "StudyDescription" : "*Chest*",
              "PatientName" : ""

You might be interested in including the Normalize option to bypass the normalization of the outgoing C-FIND queries. For instance, for the InstitutionName to be included at the Study level, one would run:

$ curl -v http://localhost:8042/modalities/sample/query -X POST -d \

You will receive back an ID which can be used to retrieve more information with GET commands or C-Move requests with a POST Command:

   "ID": "5af318ac-78fb-47ff-b0b0-0df18b0588e0",
   "Path": "/queries/5af318ac-78fb-47ff-b0b0-0df18b0588e0"

Additional Options

You can use patient identifiers by including the * within your search. For example if you were searching for a name beginning with Jones you can do:


If you wanted to search for a name with the words Jo anywhere within it you can do:


To perform date searches you can specify within StudyDate a starting date and/or a before date. For example "StudyDate":"20180323-" would search for all study dates after the specified date to now. Doing "StudyDate":"20180323-20180325" would search for all study dates between the specified date.

Reviewing Level

$ curl --request GET --url http://localhost:8042/queries/5af318ac-78fb-47ff-b0b0-0df18b0588e0/level

Will retrieve the level with which the query was performed, Study, Series or Instance.

Reviewing Modality

$ curl --request GET --url http://localhost:8042/queries/5af318ac-78fb-47ff-b0b0-0df18b0588e0/modality

Will provide the modality name which the original query was performed against.

Reviewing Query

To retrieve information on what identifiers the query was originally performed using you can use the query filter:

$ curl --request GET --url http://localhost:8042/queries/5af318ac-78fb-47ff-b0b0-0df18b0588e0/query

Reviewing Query Answers

You are able to individually review each answer returned by performing a GET with the answers parameter:

$ curl --request GET --url http://localhost:8042/queries/5af318ac-78fb-47ff-b0b0-0df18b0588e0/answers

You will get a JSON back with numbered identifiers for each answer you received back. For example because we performed a Study level query we received back 5 studies answers back. We are able to query each answer for content details:

$ curl --request GET --url http://localhost:8042/queries/5af318ac-78fb-47ff-b0b0-0df18b0588e0/answers/0/content

If there are content items missing, you may add them by adding that identifier to the original query. For example if we wanted Modalities listed in this JSON answer in the initial query we would add to the POST body: "ModalitiesInStudy":""

Performing Retrieve (C-Move)

You can perform a C-Move to retrieve all studies within the original query using a post command and identifying the Modality (named in this example Orthanc), to be one to in the POST contents:

$ curl --request POST --url http://localhost:8042/queries/5af318ac-78fb-47ff-b0b0-0df18b0588e0/retrieve --data Orthanc

You are also able to perform individual C-Moves for a content item by specifying that individual content item:

$ curl --request POST --url http://localhost:8042/queries/5af318ac-78fb-47ff-b0b0-0df18b0588e0/answers/0/retrieve --data Orthanc

If C-Moves take too long (for example, performing a C-Move of a big study), you may run the request in asynchronous mode, which will create a job in Orthanc:

$ curl --request POST --url http://localhost:8042/queries/5af318ac-78fb-47ff-b0b0-0df18b0588e0/retrieve \
  --data '{"TargetAet":"Orthanc","Synchronous":false}'

The answer of this POST request is the job ID taking care of the C-Move command, whose status can be monitored in order to detect failure or completion:

    "ID" : "11541b16-e368-41cf-a8e9-3acf4061d238",
    "Path" : "/jobs/11541b16-e368-41cf-a8e9-3acf4061d238"

Performing Finds within Orthanc

Performing a find within the local database of Orthanc is very similar to using Queries against DICOM modalities and the additional options listed above work with find also. When performing a find, you will receive the Orthanc ID’s of all the matched items within your find. For example if you perform a study level find and 5 Studies match you will receive 5 study level Orthanc ID’s in JSON format as a response:

$ curl --request POST --url http://localhost:8042/tools/find \
  --data '{
            "Level" : "Instance",
            "Query" : {
              "Modality" : "CR",
              "StudyDate" : "20180323-",
              "PatientID" : "*"

Setting the Expand field to true in the POST body of the query will automatically report details about each study:

$ curl -d '{"Level":"Study","Query":{"PatientName":"KNIX"}}'
$ curl -d '{"Level":"Study","Query":{"PatientName":"KNIX"},"Expand":true}'
    "ID" : "b9c08539-26f93bde-c81ab0d7-bffaf2cb-a4d0bdd0",
    "IsStable" : true,
    "LastUpdate" : "20180414T091528",
    "MainDicomTags" : {
       "InstitutionName" : "0ECJ52puWpVIjTuhnBA0um",
       "ReferringPhysicianName" : "1",
       "StudyDate" : "20070101",
       "StudyDescription" : "Knee (R)",
       "StudyID" : "1",
       "StudyInstanceUID" : "1.2.840.113619.2.176.2025.1499492.7391.1171285944.390",
       "StudyTime" : "120000.000000"
    "ParentPatient" : "6816cb19-844d5aee-85245eba-28e841e6-2414fae2",
    "PatientMainDicomTags" : {
       "PatientID" : "ozp00SjY2xG",
       "PatientName" : "KNIX"
    "Series" : [
    "Type" : "Study"

Here is a sample REST API call to find the Orthanc identifiers of all the DICOM series generated by an imaging modality whose “Device Serial Number (0018,1000)” DICOM tag is equal to “123”:

$ curl -X POST http://localhost:8042/tools/find -d '{"Level":"Series","Query":{"DeviceSerialNumber":"123"},"Expand":true}'

If you are interested by a list of several items (in this case, in a list of serial numbers), just separate them with backslashes as would do with DICOM C-FIND:

$ curl -X POST http://localhost:8042/tools/find -d '{"Level":"Series","Query":{"DeviceSerialNumber":"123\\abc"},"Expand":true}'

Additional Options

You also have the ability to limit the responses by specifying a limit within the body of the POST message. For example:


Since Orthanc 1.11.0, you may also request a specific list of tags in the response (like in a C-FIND) even if these tags are not stored in the MainDicomTags or if the tags needs to be computed (like ModalitiesInStudy). This RequestedTags option is available only if you specify "Expand": true:

$ curl -X POST http://localhost:8042/tools/find -d '
    "Level": "Studies",
    "Expand": true,
    "Query": {
      "StudyDate": "20220502"
    "RequestedTags": ["PatientName", "PatientID", "StudyDescription", "StudyDate", "StudyInstanceUID", "ModalitiesInStudy", "NumberOfStudyRelatedSeries"]

This query will return a response like this one:

    "ID" : "8a8cf898-ca27c490-d0c7058c-929d0581-2bbf104d",
    "IsStable" : true,
    "LastUpdate" : "20220428T074549",
    "MainDicomTags" : {
    "..." : "...",
    "RequestedTags" : {
       "PatientName" : "Patient",
       "PatientID" : "1",
       "StudyDescription" : "Description",
       "StudyDate" : "20220502",
       "StudyInstanceUID" : "1.2.3",
       "ModalitiesInStudy" : "CT\\SEG\\SR",
       "NumberOfStudyRelatedSeries" : "3"
    "Series" : [ "93034833-163e42c3-bc9a428b-194620cf-2c5799e5" ],
    "Type" : "Study"

Important: Starting with Orthanc 1.12.0, this route in the REST API also provide the Labels and LabelsConstraint options to bring support for labels.

Tracking changes

Whenever Orthanc receives a new DICOM instance, this event is recorded in the so-called “Changes Log”. This enables remote scripts to react to the arrival of new DICOM resources. A typical application is auto-routing, where an external script waits for a new DICOM instance to arrive into Orthanc, then forward this instance to another modality.

The Changes Log can be accessed by the following command:

$ curl http://localhost:8042/changes

Here is a typical output:

  "Changes" : [
        "ChangeType" : "NewInstance",
        "Date" : "20130507T143902",
        "ID" : "8e289db9-0e1437e1-3ecf395f-d8aae463-f4bb49fe",
        "Path" : "/instances/8e289db9-0e1437e1-3ecf395f-d8aae463-f4bb49fe",
        "ResourceType" : "Instance",
        "Seq" : 921
        "ChangeType" : "NewSeries",
        "Date" : "20130507T143902",
        "ID" : "cceb768f-e0f8df71-511b0277-07e55743-9ef8890d",
        "Path" : "/series/cceb768f-e0f8df71-511b0277-07e55743-9ef8890d",
        "ResourceType" : "Series",
        "Seq" : 922
        "ChangeType" : "NewStudy",
        "Date" : "20130507T143902",
        "ID" : "c4ec7f68-9b162055-2c8c5888-5bf5752f-155ab19f",
        "Path" : "/studies/c4ec7f68-9b162055-2c8c5888-5bf5752f-155ab19f",
        "ResourceType" : "Study",
        "Seq" : 923
        "ChangeType" : "NewPatient",
        "Date" : "20130507T143902",
        "ID" : "dc65762c-f476e8b9-898834f4-2f8a5014-2599bc94",
        "Path" : "/patients/dc65762c-f476e8b9-898834f4-2f8a5014-2599bc94",
        "ResourceType" : "Patient",
        "Seq" : 924
  "Done" : true,
  "Last" : 924

This output corresponds to the receiving of one single DICOM instance by Orthanc. It records that a new instance, a new series, a new study and a new patient has been created inside Orthanc. Note that each changes is labeled by a ChangeType, a Date (in the ISO format), the location of the resource inside Orthanc, and a sequence number (Seq).

Note that this call is non-blocking. It is up to the calling program to wait for the occurrence of a new event (by implementing a polling loop).

This call only returns a fixed number of events, that can be changed by using the limit option:

$ curl http://localhost:8042/changes?limit=100

The flag Last records the sequence number of the lastly returned event. The flag Done is set to true if no further event has occurred after this lastly returned event. If Done is set to false, further events are available and can be retrieved. This is done by setting the since option that specifies from which sequence number the changes must be returned:

$ curl 'http://localhost:8042/changes?limit=100&since=922'

A sample code in the source distribution shows how to use this Changes API to implement a polling loop.

Deleting resources from Orthanc

Deleting patients, studies, series or instances

Deleting DICOM resources (i.e. patients, studies, series or instances) from Orthanc is as simple as using a HTTP DELETE on the URI of this resource.

Concretely, you would first explore the resources that are stored in Orthanc as explained above:

$ curl http://localhost:8042/patients
$ curl http://localhost:8042/studies
$ curl http://localhost:8042/series
$ curl http://localhost:8042/instances

Secondly, once you have spotted the resources to be removed, you would use the following command-line syntax to delete them:

$ curl -X DELETE http://localhost:8042/patients/dc65762c-f476e8b9-898834f4-2f8a5014-2599bc94
$ curl -X DELETE http://localhost:8042/studies/c4ec7f68-9b162055-2c8c5888-5bf5752f-155ab19f
$ curl -X DELETE http://localhost:8042/series/cceb768f-e0f8df71-511b0277-07e55743-9ef8890d
$ curl -X DELETE http://localhost:8042/instances/8e289db9-0e1437e1-3ecf395f-d8aae463-f4bb49fe

Starting with Orthanc 1.9.4, it is also possible to POST on the new route /tools/bulk-delete to delete at once a set of multiple DICOM resources that are not related (i.e. that don’t share any parent DICOM resource). A typical use case is to delete a list of DICOM instances that don’t belong to the same parent patient/study/series. The list of the Orthanc identifiers of the resources to be deleted (that may indifferently correspond to patients, studies, series or instances) must be provided in an argument Resources in the body of the request. Here is a sample call:

$ curl http://localhost:8042/tools/bulk-delete -d '{"Resources":["b6da0b16-a25ae9e7-1a80fc33-20df01a9-a6f7a1b0","d6634d97-24379e4a-1e68d3af-e6d0451f-e7bcd3d1"]}'

Clearing log of changes

As described above, Orthanc keeps track of all the changes that occur in the DICOM store. This so-called “Changes Log” is accessible at the following URI:

$ curl http://localhost:8042/changes

To clear the content of the Changes Log, simply DELETE this URI:

$ curl -X DELETE http://localhost:8042/changes

Log of exported resources

For medical traceability, Orthanc can be configured to store a log of all the resources that have been exported to remote modalities:

$ curl http://localhost:8042/exports

In auto-routing scenarios, it is important to prevent this log to grow indefinitely as incoming instances are routed. You can either disable this logging by setting the option LogExportedResources to false in the configuration file, or periodically clear this log by DELETE-ing this URI:

$ curl -X DELETE http://localhost:8042/exports

NB: Starting with Orthanc 1.4.0, the LogExportedResources is set to false by default. If the logging is desired, set this option to true.

Anonymization and modification

The process of anonymizing and modifying DICOM resources is documented in a separate page.

Further reading

The examples above have shown you the basic principles for driving an instance of Orthanc through its REST API. All the possibilities of the API have not been described: