def METHOD_NAME(self):
    self.tube_settings[Tags.STRUCTURE_START_MM] = [1.5, 0, 1.5]
    self.tube_settings[Tags.STRUCTURE_END_MM] = [1.5, 5, 1.5]
    self.tube_settings[Tags.STRUCTURE_RADIUS_MM] = np.sqrt(3*0.25)     # diagonal of exactly one voxel
    ts = CircularTubularStructure(self.global_settings, self.tube_settings)
    assert ts.geometrical_volume[1, 1, 1] == 1
    assert ts.geometrical_volume[0, 1, 0] == 0
    assert ts.geometrical_volume[0, 1, 2] == 0
    assert ts.geometrical_volume[2, 1, 0] == 0
    assert ts.geometrical_volume[2, 2, 2] == 0
    assert 0 < ts.geometrical_volume[0, 1, 1] < 1
    assert 0 < ts.geometrical_volume[1, 1, 0] < 1
    assert 0 < ts.geometrical_volume[1, 1, 2] < 1
    assert 0 < ts.geometrical_volume[2, 1, 1] < 1