DICOM Service API v2 Changes

This reference guide provides you with a summary of the changes in the V2 API of the DICOMĀ® service. To see the full set of capabilities in v2, see the DICOM Conformance Statement v2.

Summary of changes in v2


Lenient validation of optional attributes

In previous versions, a Store request fails if any of the required or searchable attributes fails validation. Beginning with v2, the request fails only if required attributes fail validation.

Failed validation of attributes not required by the API results in the file being stored with a warning in the response. Warnings result in an HTTP return code of 202 Accepted and the response payload contains the WarningReason tag (0008, 1196).

A warning is given about each failing attribute per instance. When a sequence contains an attribute that fails validation, or when there are multiple issues with a single attribute, only the first failing attribute reason is noted.

There are some notable behaviors for optional attributes that fail validation:

  • Searches for the attribute that failed validation returns the study/series/instance if the value is corrected in one of the few ways mentioned below.
  • The attributes aren't returned when retrieving metadata via WADO /metadata endpoints.

Retrieving a study/series/instance always returns the original binary files with the original attributes, even if those attributes failed validation.

If an attribute is padded with nulls, the attribute is indexed when searchable and is stored as is in dicom+json metadata. No validation warning is provided.


Single frame retrieval support

Single frame retrieval is supported by adding the following Accept header:

  • application/octet-stream; transfer-syntax=*

Search results might be incomplete for extended query tags with validation warnings

In the v1 API and continued for v2, if an extended query tag has any errors, because one or more of the existing instances had a tag value that couldn't be indexed, then subsequent search queries containing the extended query tag return erroneous-dicom-attributes as detailed in the documentation. However, tags (also known as attributes) with validation warnings from STOW-RS are not included in this header. If a store request results in validation warnings for searchable attributes at the time the instance was stored, those attributes may not be used to search for the stored instance. However, any searchable attributes that failed validation will be able to return results if the values are overwritten by instances in the same study/series that are stored after the failed one, or if the values are already stored correctly by a previous instance. If the attribute values are not overwritten, then they will not produce any search results.

An attribute can be corrected in the following ways:

  • Delete the stored instance and upload a new instance with the corrected data
  • Upload a new instance in the same study/series with corrected data

Fewer Study, Series, and Instance attributes are returned by default

The set of attributes returned by default has been reduced to improve performance. See the detailed list in the search response documentation.

Attributes added newly to default tags.

Tag level Tag Attribute Name
Study (0008, 1030) StudyDescription
Series (0008, 1090) ManufacturerModelName

Attributes removed from default tags.

Tag level Tag Attribute Name
Study (0008, 0005) SpecificCharacterSet
Study (0008, 0030) StudyTime
Study (0008, 0056) InstanceAvailability
Study (0008, 0201) TimezoneOffsetFromUTC
Study (0010, 0040) PatientSex
Study (0020, 0010) StudyID
Series (0008, 0005) SpecificCharacterSet
Series (0008, 0201) TimezoneOffsetFromUTC
Series (0008, 103E) SeriesDescription
Series (0040, 0245) PerformedProcedureStepStartTime
Series (0040, 0275) RequestAttributesSequence
Instance (0008, 0005) SpecificCharacterSet
Instance (0008, 0016) SOPClassUID
Instance (0008, 0056) InstanceAvailability
Instance (0008, 0201) TimezoneOffsetFromUTC
Instance (0020, 0013) InstanceNumber
Instance (0028, 0010) Rows
Instance (0028, 0011) Columns
Instance (0028, 0100) BitsAllocated
Instance (0028, 0008) NumberOfFrames

All the removed tags are part of additional tags which will be returned when queried with includefield = all.

Null padded attributes can be searched for with or without padding

When an attribute was stored using null padding, it can be searched for with or without the null padding in uri encoding. Results retrieved are for attributes stored both with and without null padding.


The completed status has been renamed to succeeded

To align with Microsoft's REST API guidelines, the completed status has been renamed to succeeded.

Change Feed

Change feed now accepts a time range

The Change Feed API now accepts optional startTime and endTime parameters to help scope the results. Changes within a time range can still be paginated using the existing offset and limit parameters. The offset is relative to the time window defined by startTime and endTime. For example, the fifth change feed entry starting from 7/24/2023 at 09:00 AM UTC would use the query string ?startTime=2023-07-24T09:00:00Z&offset=5.

For v2, it's recommended to always include a time range to improve performance.


DICOMĀ® is the registered trademark of the National Electrical Manufacturers Association for its Standards publications relating to digital communications of medical information.