Thanks fleetwoodfc! Unfortunately it doesn't work. The conformance statement from the PACS I'm querying says it accepts all valid keys, and the set being used is defined by the client:
Philips iSite Server query keys as well. In practice, the set actually used is defined
by client-side requests so only a pertinent subset would be used. Table 5 lists the
essential tags that Philips iSite Server will expect any Query/Retrieve SCP to
support for the Study Root Information Model.
Table 5: DICOM data elements supported for SOP Class ‘Study Root Query/Retrieve
Information Model - FIND'
Level Description Tag Type
Study Patient’s Name (0010,0010) R
Study Patient ID (0010,0020) U
Study Study ID (0020,0010) R
Study Study Instance UID (0020,000D) U
Study Study Date (0020,0020) R
Study Study Time (0020,0030) R
Study Accession Number (0008,0050) R
Study Referring Physician (0008,0090) O