get_half_life_from_nifti
==============================================

.. py:function:: petpal.utils.image_io.get_half_life_from_nifti(image_path: str)

   Retrieves the radionuclide half-life from a nifti image file.

   This function first checks if the provided nifti image file exists. It then derives
   the corresponding metadata file path using :func:`_gen_meta_data_filepath_for_nifti`
   and finally retrieves the half-life from the metadata using :func:`get_half_life_from_meta`.

   :param image_path: Path to the nifti image file.
   :type image_path: str

   :returns: *float* -- The radionuclide half-life extracted from the metadata file.

   :raises FileNotFoundError: If the nifti image file does not exist at the provided path.