Add missed change (#374)

Signed-off-by: M Q <[email protected]>

Signed-off-by: M Q <[email protected]>

Author: MMelQin

monai/deploy/operators/dicom_seg_writer_operator.py

@@ -305,7 +305,10 @@ def create_dicom_seg(self, image: np.ndarray, dicom_series: DICOMSeries, output_
             for k, v in self._custom_tags.items():
                 if isinstance(k, str) and isinstance(v, str):
                     try:
-                        seg[k].value = v
+                        if k in seg:
+                            seg.data_element(k).value = v
+                        else:
+                            seg.update({k: v})
                     except Exception as ex:
                         # Best effort for now.
                         logging.warning(f"Tag {k} was not written, due to {ex}")