code: def get_unique_field_values(dcm_file_list, field_name):
      
      field_values = set()
  
      for dcm in dcm_file_list:
          field_values.add(str(DicomFile(dcm).get_attributes(field_name)))
  
      return field_values
docs: Return a set of unique field values from a list of DICOM files
  
      Parameters
      ----------
      dcm_file_list: iterable of DICOM file paths
  
      field_name: str
       Name of the field from where to get each value
  
      Returns
      -------
      Set of field values