DICOM PS3.18 2021b - Web Services

9 URI Service (Current)
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# 9 URI Service

## 9.1 Overview

The URI Service, also known as WADO-URI, enables a user agent to retrieve representations of Instances using HTTP.

### 9.1.1 Resource Descriptions

The URI Service does not define resources in the form of a Target Resource Path, such as {/resource}. The Target URI of each transaction is a reference to the Base URI ("/") and the Target Resource is identified using query parameter values. The resources for the URI Service are instances of Composite Storage SOP Classes defined in PS3.4.

### 9.1.2 Common Query Parameters

The Query Parameters specified in this Section may be used with either the Retrieve DICOM Instance or Retrieve Rendered Instance transactions, and are applicable to all supported SOP Classes.

#### 9.1.2.1 Mandatory Query Parameters

The origin server shall support Query Parameters as required in Table 9.1.2-1.

The user agent shall supply in the request Query Parameters as required in Table 9.1.2-1.

The Query Parameters may appear in any order.

Table 9.1.2-1. Mandatory Query Parameters

Name | Values | Usage | Section
--- | --- | --- | ---
User Agent | Origin Server
requestType | "WADO" | M | M | Section 9.1.2.1.1
studyUID | uid | M | M | Section 9.1.2.1.3
seriesUID | uid | M | M | Section 9.1.2.1.3
objectUID | uid | M | M | Section 9.1.2.1.4

See Section 8.3.

### Note

To identify a SOP Instance, only a SOP Instance UID is required, because any UID is globally unique. However, the Standard requires that the UIDs of the higher levels in the DICOM Information Model (i.e., series and study) are specified, in order to support the use of DICOM devices that support only the baseline hierarchical (rather than extended relational) Query/Retrieve model, which requires the Study Instance UID and Series Instance UID to be defined when retrieving an Instance, as defined in PS3.4.

##### 9.1.2.1.1 Request Type

    requestType = %s"requestType=" token

    token       = "WADO"

This parameter specifies that this is a URI service request. The parameter name shall be "requestType", and the value shall be "WADO".

If the value is other than "WADO", and the origin server does not support the value, the response shall be 400 (Bad Request), and may include a payload containing an appropriate error message.

##### 9.1.2.1.2 Study UID

    study = %s"studyUID=" uid

The value of this parameter is a Study Instance UID.

##### 9.1.2.1.3 Series UID

    series = %s"seriesUID=" uid

The value of this parameter is a Series Instance UID.

##### 9.1.2.1.4 Instance UID

    instance = %s"objectUID=" uid

The value of this parameter is a SOP Instance UID.

#### 9.1.2.2 Optional Query Parameters

The parameters defined in this section are optional for all URI requests.

Table 9.1.2-2. Optional Query Parameters

Key | Values | Usage | Section
--- | --- | --- | ---
User Agent | Origin Server
contentType | media-type | O | O | Section 8.3.3.1
charset | token | O | O | Section 8.3.3.2

See Section 8.3.

##### 9.1.2.2.1 Acceptable Media Types

The Accept Query Parameter specifies the Acceptable Media Types for the response payload. See Section 8.7.5. The case-sensitive name of the parameter is "contentType". Its syntax is:

    accept = %s"contentType=" dicom / 1#rendered-media-type

The value of this parameter, if present, shall be either application/dicom, or one or more of the Rendered Media Types.

The DICOM Media Type transfer-syntax and character set parameters are forbidden in the request. If either are present, the response shall be 400 (Bad Request), and may include a payload containing an appropriate error message.

See Section 8.7.5 for other errors related to this parameter.

### Note

URI origin servers may support Transfer Syntax and charset Query Parameters. This is different from the approach used by the DICOM RESTful services, which uses transfer-syntax and charset media type parameters.

##### 9.1.2.2.2 Acceptable Character Sets

    charset-qp = %s"charset=" 1#(charset [weight])

The value of this parameter is a comma-separated list of one or more character-set identifiers. See Section 8.8.1.

### 9.1.3 Common Media Types

The origin server shall support the application/dicom media type as described in Section 8.7.3.1 and Rendered Media Types as described in Section 8.7.4.

Support for the Transfer Syntax and Character Set media type parameters is forbidden for URI Services.

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DICOM PS3.18 2021b - Web Services