Anthony Edwards, who has played Dr. Mark Greene on “ER,” TV’s top-rated series since its premiere in 1994, is hanging up his stethoscope and will leave the show when his contract expires after the 2001-2002 season, he said on Tuesday. “I love to act, but to act every day for 10 months a year and not see your kids . . . It’s more of a family thing,” Edwards, 38, who with his wife, Jeanine Lobell, has three young children, told the Associated Press. Edwards’s announcement came as a surprise to NBC, says the Hollywood Reporter. The network reportedly has a commitment to the series through the 2003-04 season at least. Edwards (along with other cast members) received a $1 million bonus two years ago when the producer of the show, Warner Bros. Television, signed an unprecedented $13-million per episode licensing deal with NBC. He said, however, that his departure is not an attempt to cadge a new contract, notes the trade paper. On the show, his character has suffered through divorce, estrangement from his daughter, a serious assault, the deaths of both parents and cancer, the last of which would seem an obvious exit ploy . . . though, Edwards, said, there are always some others. “There are a lot of El trains in Chicago,” he joked. “You could trip in front of any one of them.”