LAS VEGAS — The Motion Picture Association of America is changing its rating system to better inform parents about violence in movies.

CEO Christopher Dodd announced the tweaks at the annual CinemaCon movie-theater convention in Las Vegas yesterday.

The White House has called on the movie industry to give parents better tools to monitor violence in media since the Newtown, Conn., school massacre.

The new system will include descriptions about why a movie received its ratings.

For example, the rating might cite “strong carnage” or “war violence.”