def derenzo_sources(space, min_pt=None, max_pt=None):
    """Create the PET/SPECT Derenzo sources phantom.

    The Derenzo phantom contains a series of circles of decreasing size.

    In 3d the phantom is simply the 2d phantom extended in the z direction as
    cylinders.

    Parameters
    ----------
    space : `DiscreteLp`
        Space in which the phantom should be created, must be 2- or
        3-dimensional. If ``space.shape`` is 1 in an axis, a corresponding
        slice of the phantom is created (instead of squashing the whole
        phantom into the slice).
    min_pt, max_pt : array-like, optional
        If provided, use these vectors to determine the bounding box of the
        phantom instead of ``space.min_pt`` and ``space.max_pt``.
        It is currently required that ``min_pt >= space.min_pt`` and
        ``max_pt <= space.max_pt``, i.e., shifting or scaling outside the
        original space is not allowed.

        Providing one of them results in a shift, e.g., for ``min_pt``::

            new_min_pt = min_pt
            new_max_pt = space.max_pt + (min_pt - space.min_pt)

        Providing both results in a scaled version of the phantom.

    Returns
    -------
    phantom : ``space`` element
        The Derenzo source phantom in the given space.
    """
    if space.ndim == 2:
        return ellipsoid_phantom(space, _derenzo_sources_2d(), min_pt, max_pt)
    if space.ndim == 3:
        return ellipsoid_phantom(
            space, cylinders_from_ellipses(_derenzo_sources_2d()),
            min_pt, max_pt)
    else:
        raise ValueError('dimension not 2, no phantom available')
Create the PET/SPECT Derenzo sources phantom.

    The Derenzo phantom contains a series of circles of decreasing size.

    In 3d the phantom is simply the 2d phantom extended in the z direction as
    cylinders.

    Parameters
    ----------
    space : `DiscreteLp`
        Space in which the phantom should be created, must be 2- or
        3-dimensional. If ``space.shape`` is 1 in an axis, a corresponding
        slice of the phantom is created (instead of squashing the whole
        phantom into the slice).
    min_pt, max_pt : array-like, optional
        If provided, use these vectors to determine the bounding box of the
        phantom instead of ``space.min_pt`` and ``space.max_pt``.
        It is currently required that ``min_pt >= space.min_pt`` and
        ``max_pt <= space.max_pt``, i.e., shifting or scaling outside the
        original space is not allowed.

        Providing one of them results in a shift, e.g., for ``min_pt``::

            new_min_pt = min_pt
            new_max_pt = space.max_pt + (min_pt - space.min_pt)

        Providing both results in a scaled version of the phantom.

    Returns
    -------
    phantom : ``space`` element
        The Derenzo source phantom in the given space.