retrieveInstance method
RetrieveInstance returns instance associated with the given study, series, and SOP Instance UID.
See RetrieveTransaction. For details on the implementation of RetrieveInstance, see DICOM study/series/instances and DICOM instances in the Cloud Healthcare API conformance statement. For samples that show how to call RetrieveInstance, see Retrieve an instance.
Request parameters:
parent - Required. The name of the DICOM store that is being accessed.
For example,
projects/{project_id}/locations/{location_id}/datasets/{dataset_id}/dicomStores/{dicom_store_id}.
Value must have pattern
^projects/\[^/\]+/locations/\[^/\]+/datasets/\[^/\]+/dicomStores/\[^/\]+$.
dicomWebPath - Required. The path of the RetrieveInstance DICOMweb
request. For example,
studies/{study_uid}/series/{series_uid}/instances/{instance_uid}.
Value must have pattern
^studies/\[^/\]+/series/\[^/\]+/instances/\[^/\]+$.
$fields - Selector specifying which fields to include in a partial
response.
Completes with a HttpBody.
Completes with a commons.ApiRequestError if the API endpoint returned an error.
If the used http.Client completes with an error when making a REST call,
this method will complete with the same error.
Implementation
async.Future<HttpBody> retrieveInstance(
  core.String parent,
  core.String dicomWebPath, {
  core.String? $fields,
}) async {
  final queryParams_ = <core.String, core.List<core.String>>{
    if ($fields != null) 'fields': [$fields],
  };
  final url_ = 'v1/' +
      core.Uri.encodeFull('$parent') +
      '/dicomWeb/' +
      core.Uri.encodeFull('$dicomWebPath');
  final response_ = await _requester.request(
    url_,
    'GET',
    queryParams: queryParams_,
  );
  return HttpBody.fromJson(response_ as core.Map<core.String, core.dynamic>);
}