Storage Service Examples

The DICOM Storage Service provides a mechanism for an SCU to request the transfer of supported Storage SOP Class instances to the service provider. Transfer is accomplished by utilising the DIMSE C-STORE service.

In essence, if you want to send or receive DICOM images or waveforms or any other type of data supported by the Storage SOP Classes, then the Storage Service is what you’re looking for.

Storage SCU

Associate with a peer DICOM Application Entity and request the transfer of a single CT dataset.

from pydicom import dcmread

from pynetdicom import AE
from pynetdicom.sop_class import CTImageStorage

# Initialise the Application Entity
ae = AE()

# Add a requested presentation context
ae.add_requested_context(CTImageStorage)

# Read in our DICOM CT dataset
ds = dcmread('path/to/dataset')

# Associate with peer AE at IP 127.0.0.1 and port 11112
assoc = ae.associate('127.0.0.1', 11112)

if assoc.is_established:
    # Use the C-STORE service to send the dataset
    # returns a pydicom Dataset
    status = assoc.send_c_store(ds)

    # Check the status of the storage request
    if 'Status' in status:
        # If the storage request succeeded this will be 0x0000
        print('C-STORE request status: 0x{0:04x}'.format(status.Status))
    else:
        print('Connection timed out or invalid response from peer')

    # Release the association
    assoc.release()
else:
    print('Association rejected or aborted')

Of course it’s rarely the case that someone wants to store just CT images, so you can also use the inbuilt StoragePresentationContexts when setting the requested contexts or just add as many contexts as you need.

from pynetdicom import AE, StoragePresentationContexts

ae = AE()
ae.requested_contexts = StoragePresentationContexts

You can also set the requested contexts on a per association basis.

from pydicom import dcmread

from pynetdicom import AE, build_context
from pynetdicom.sop_class import CTImageStorage, MRImageStorage

# Initialise the Application Entity
ae = AE()

# Create some presentation contexts
ct_context = build_context(CTImageStorage)
mr_context = build_context(MRImageStorage)

# Associate with peer AE at IP 127.0.0.1 and port 11112
assoc = ae.associate('127.0.0.1', 11112, contexts=[ct_context])
assoc.release()

assoc = ae.associate('127.0.0.1', 11112, contexts=[mr_context])
assoc.release()

Storage SCP

Create an AE that supports the Storage Service and then listen for association requests on port 11112. When a storage request is received over the association we write the dataset to file and then return a 0x0000 Success status.

If you’re going to write SOP instances (datasets) to file it’s recommended that you ensure the file is conformant with the DICOM File Format, which requires adding the File Meta Information.

from pydicom.dataset import Dataset

from pynetdicom import (
    AE,
    StoragePresentationContexts,
    PYNETDICOM_IMPLEMENTATION_UID,
    PYNETDICOM_IMPLEMENTATION_VERSION
)

# Initialise the Application Entity and specify the listen port
ae = AE(port=11112)

# Add the supported presentation contexts
ae.supported_contexts = StoragePresentationContexts

# Implement the AE.on_c_store callback
def on_c_store(ds, context, info):
    """Store the pydicom Dataset `ds`.

    Parameters
    ----------
    ds : pydicom.dataset.Dataset
        The dataset that the peer has requested be stored.
    context : namedtuple
        The presentation context that the dataset was sent under.
    info : dict
        Information about the association and storage request.

    Returns
    -------
    status : int or pydicom.dataset.Dataset
        The status returned to the peer AE in the C-STORE response. Must be
        a valid C-STORE status value for the applicable Service Class as
        either an ``int`` or a ``Dataset`` object containing (at a
        minimum) a (0000,0900) *Status* element.
    """
    # Add the DICOM File Meta Information
    meta = Dataset()
    meta.MediaStorageSOPClassUID = ds.SOPClassUID
    meta.MediaStorageSOPInstanceUID = ds.SOPInstanceUID
    meta.ImplementationClassUID = PYNETDICOM_IMPLEMENTATION_UID
    meta.ImplementationVersionName = PYNETDICOM_IMPLEMENTATION_VERSION
    meta.TransferSyntaxUID = context.transfer_syntax

    # Add the file meta to the dataset
    ds.file_meta = meta

    # Set the transfer syntax attributes of the dataset
    ds.is_little_endian = context.transfer_syntax.is_little_endian
    ds.is_implicit_VR = context.transfer_syntax.is_implicit_VR

    # Save the dataset using the SOP Instance UID as the filename
    ds.save_as(ds.SOPInstanceUID, write_like_original=False)

    # Return a 'Success' status
    return 0x0000

ae.on_c_store = on_c_store

# Start listening for incoming association requests
ae.start()

As with the SCU you can also just support only the contexts you’re interested in.

from pynetdicom import AE
from pynetdicom.sop_class import CTImageStorage

ae = AE(port=11112)

# Add a supported presentation context
ae.add_supported_context(CTImageStorage)

def on_c_store(ds, context, info):
    # Don't store anything but respond with `Success`
    return 0x0000

ae.on_c_store = on_c_store

ae.start()