code: def derenzo_sources(space, min_pt=None, max_pt=None):
      
      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')
docs: 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.