def dose_to_vtk(dose_id):
    img_data = json.loads(thinknode.get_immutable(iam, 'dicom', dose_id))

    img = rt_types.image_3d()
    img.from_json(img_data)
    img2 = img.expand_data()

    vtk.write_vtk_image3('E:/dicom/dose.vtk', img2)