vessel_tree structure
    :param vessel_tree:  vt structure
    :param outfile: filename with .vtk extension
    :param text_label: text label like 'porta' or 'hepatic_veins'
    :param lc_all: LC_ALL locale settings. Controls float numbers
        format (dot or colon). If is set to "C" dot is used.
        If None is used no processing is done
    :return:

def vt2vtk_file(vessel_tree, outfile, text_label=None, lc_all="C"):
    """
    vessel_tree structure
    :param vessel_tree:  vt structure
    :param outfile: filename with .vtk extension
    :param text_label: text label like 'porta' or 'hepatic_veins'
    :param lc_all: LC_ALL locale settings. Controls float numbers
        format (dot or colon). If is set to "C" dot is used.
        If None is used no processing is done
    :return:
    """

    polyData = vt2polyData(vessel_tree, text_label=text_label)
    if lc_all is not None:
        import locale
        locale.setlocale(locale.LC_ALL, 'C')
    writer = vtk.vtkPolyDataWriter()
    writer.SetFileName(outfile)
    try:
        writer.SetInputData(polyData)
    except:
        logger.warning("old vtk is used")
        writer.SetInput(polyData)
    writer.Write()
    return polyData