def get_project_subject_session(nrrd_file):
    """
    (str) -> tuple(str,str,str)
    Return a tuple which contains (project,subject,session) from the given nrrd fiel.
    >>>nrrd_file = '/paulsen/MRx/PHD_032/0454/31774/ANONRAW/0454_31774_DWI-31_7.nrrd'
    >>>get_scan_type(nrrd_file)
    (PHD_032,0450,31774)
    """
    nfs = nrrd_file.split("/")
    return (nfs[3], nfs[4], nfs[5])