diff --git a/internal/api/handlers/dicom.go b/internal/api/handlers/dicom.go
index 876cd53..1a6f514 100644
--- a/internal/api/handlers/dicom.go
+++ b/internal/api/handlers/dicom.go
@@ -128,7 +128,7 @@ func (h *DicomHandler) ForwardRequest(w http.ResponseWriter, r *http.Request) {
 					queryParams.Del("StudyInstanceUID")
 
 					// For DICOMweb, we can use comma-separated UIDs
-					queryParams.Set("StudyInstanceUID", strings.Join(claims.StudyIUIDs, ","))
+					queryParams.Set("StudyInstanceUID", claims.StudyIUIDs[0])
 
 					h.logger.Debug("Filtering by studies",
 						zap.Strings("studies", claims.StudyIUIDs))