CP-2303

<informaltable rules="all" frame="box"> <tr> <td> <para><emphasis role="italic">Amend DICOM PS3.18 as follows (changes to existing text are bold and <emphasis role="bold"><emphasis role="underline" >underlined</emphasis></emphasis> for additions and <emphasis role="bold" ><emphasis role="strikethrough">struckthrough</emphasis></emphasis> for removals):</emphasis></para> </td> </tr> </informaltable> <section label="8.7.3.3" status="4" xml:id="sect_8.7.3.3"> <title>Bulkdata Media Types Bulkdata representations are only supported by RESTful services. There are two categories of Bulkdata: uncompressed and compressed. The Selected Media Type will be the default media type for the Resource Category when the origin server supports none of the Acceptable Media Types, as described in , unless the origin server has only access to the pixel data in lossy compressed form or the pixel data in a lossless compressed form that is of such length that it cannot be encoded in the Explicit VR Little Endian Transfer Syntax. The origin server may support additional Transfer Syntaxes. If no media type Transfer Syntax parameter is specified, then the Explicit VR Little Endian Transfer Syntax "1.2.840.10008.1.2.1" shall be used, unless the origin server has only access to the pixel data in lossy compressed form or the pixel data in a lossless compressed form that is of such length that it cannot be encoded in the Explicit VR Little Endian Transfer Syntax. The tables in this section have no entries for the URI service, since they do not support separate retrieval of Bulkdata. Depending on the Selected Media Type, the pixel data of a resource in the Single Frame Image Resource Category is encoded in: one compressed Bulkdata representation, or one uncompressed Bulkdata representation. Depending on the Selected Media Type, the pixel data of a resource in the Multi-Frame Image Resource Category is encoded in: multiple Single Frame Image compressed Bulkdata representations: one for each frame, or one Multi-Frame Image uncompressed Bulkdata representation. Depending on the Selected Media Type, the pixel data of a resource in the Video Resource Category is encoded in: one Video compressed Bulkdata representation, or one Video uncompressed Bulkdata representation.

Uncompressed Bulkdata Media Types specifies the default media type and Transfer Syntax UIDs, by Resource Category (see ) that can be used with uncompressed Bulkdata for the RESTful services. Uncompressed Bulkdata is encoded as a stream of uncompressed bytes (octets) in Little Endian byte order. This is the same encoding defined in for the returned value of the getData() call for uncompressed Bulkdata. In a Multi-Frame Image with a Bits Allocated (0028,0100) of 1 that is uncompressed, the individual frames are not padded, therefore successive bits are packed into bytes or words in Native format as described in . This means that if only selected frames of a Multi-Frame Image are to be encoded, each needs to be extracted from the pixel data and successively concatenated with no padding at the start of first byte of the first frame, and with no padding between successive encoded frames.

Transfer Syntax UIDs for Uncompressed Data in Bulkdata
Category	Media Type	Transfer Syntax UID	Transfer Syntax Name	RESTful
Single Frame Image	application/octet-stream	1.2.840.10008.1.2.1	Explicit VR Little Endian	D
Multi-Frame Image	application/octet-stream	1.2.840.10008.1.2.1	Explicit VR Little Endian	D
Video	application/octet-stream	1.2.840.10008.1.2.1	Explicit VR Little Endian	D
Text	application/octet-stream	1.2.840.10008.1.2.1	Explicit VR Little Endian	D
Other	application/octet-stream	1.2.840.10008.1.2.1	Explicit VR Little Endian	D

Even though the Transfer Syntax is Explicit VR Little Endian, the Value Representation is not actually encoded at the beginning of the octet-stream. The Value Representation is contained in the Metadata that references the Bulkdata.

Compressed Bulkdata Media Types Compressed Bulkdata contains only the compressed octet stream without the fragment delimiters. ... Compressed multi-frame image pixel data is encoded as individual frames. E.g., each frame of a JPEG 2000 multi-frame image will be encoded separately as image/jp2 representations, rather than as a single video/mj2 () or application/octet-stream representation. See for details on how multiple representations can be packaged into a multipart payload. ...

Retrieve Transaction ...

Request ...

Target Resources

Bulkdata Resources Bulkdata Resources (defined in ) are used to retrieve data elements (typically containing large data, such as Pixel Data) extracted from DICOM Instances.

Retrieve Transaction Bulkdata Resources
Resource	URI Template
Study Bulkdata	/studies/{study}/bulkdata
Series Bulkdata	/studies/{study}/series/{series}/bulkdata
Instance Bulkdata	/studies/{study}/series/{series}/instances/{instance}/bulkdata
Bulkdata	{bulkdataURI}

Bulkdata resources that contain pixel data can be retrieved equivalently as described in . Refer to for URI templates for Bulkdata consisting of Frame Pixel Data.

Pixel Data Resources Pixel Data Resources (defined in ) are used to retrieve data elements containing top-level pixel data from DICOM Instances. Pixel data is a subset of bulkdata. The Pixel Data resources provide a convenient method to access that specific subset.

Retrieve Transaction Pixel Data Resources
Resource	URI Template
Study Pixel Data	/studies/{study}/pixeldata
Series Pixel Data	/studies/{study}/series/{series}/pixeldata
Instance Pixel Data	/studies/{study}/series/{series}/instances/{instance}/pixeldata
Frame Pixel Data	/studies/{study}/series/{series}/instances/{instance}/frames/{frames}

Frame Pixel Data is inherently pixel data so a /pixeldata subresource is not needed in the URI Template. The Frame Pixel Data resource originally appeared in .

Behavior The origin server shall prepare representation(s) of the Target Resource in the Selected Media Type. See .

Response ...

Response Payload A success response shall have a payload containing one or more representations of the Target Resource in the Selected Media Type (see and ). The payload shall conform to . ...

Bulkdata Resource Payload The payload for a Bulkdata Resource (see ) shall contain all the bulkdata for the resource. When the resource is a single Bulkdata URI, the payload will contain the single corresponding element. When the resource is a Study, Series or Instance Bulkdata resource, the payload will contain all the bulkdata of the corresponding instance(s). Bulkdata in a multipart response shall have a Content-Location header field that corresponds to the URI contained in the corresponding Element in the Metadata.

Pixel Data Resource Payload The payload for a Pixel Data Resource (see ) shall contain all the Pixel Data of the resource. Pixel Data in a multipart response shall have a Content-Location header field that corresponds to the URI contained in the corresponding Element in the Metadata. The Pixel Data is the content of the Pixel Data (7FE0,0010), Float Pixel Data (7FE0,0008), or Double Float Pixel (7FE0,0009) Data Element in the top level Data Set, as defined in , of the corresponding instance(s). This does not include Pixel Data nested within an Icon Image Sequence or a private Data Element.

Media Types The origin server shall support the media types specified as default or required in . The application/dicom Media Type (without the "multipart/related; type="" prefix) specifies a single encoded object and shall only be used for individual Instance Resources. The origin server shall support the Transfer Syntax and Character Set media type parameters. See and . For further details on each Target Resource, see . For further details on each media type and associated transfer syntaxes, see the Section in the Media Type Reference column.

Default, Required, and Optional Media Types
Target Resource	Media Type	Usage
...
Bulkdata Resources and Pixel Data Resources	multipart/related; type="application/octet-stream"	Required
Bulkdata Resources and Pixel Data Resources	multipart/related; type= a Compressed Bulkdata Media Type	Optional
...