The NFL has enacted rule changes to try to make the kickoff safer for players. That effort will continue with further safety-related tinkering with the play, according to commissioner Roger Goodell.But if such maneuvers fail, the elimination of the kickoff remains a future consideration, Goodell said."We've made some very effective changes on the kickoff that have had a very significant impact reducing injuries," Goodell said. "It is still a play where we see a higher propensity for head injury. So we want to try to address that. We think there's still further changes that we can make. We won't take anything off the table, including the elimination."The most recent rule changes have been aimed at simply reducing kickoff returns by increasing touchbacks. Owners of the 32 NFL teams last offseason ratified a proposal by the rule-making competition committee to place the ball at the 25, rather than the 20, for touchbacks.The league's leaders plan to begin to evaluate the new rule four weeks into the season.In other player safety news, the NFL says it will spend an additional $100 million to develop new technology and support more medical research into head injuries. Under the "Play Smart. Play Safe" initiative, $60 million will be devoted toward developing technology such as improved helmets and $40 million will be allotted for medical research. TWO BRONCOS FINED: The NFL fined Broncos safety Darian Stewart and linebacker Brandon Marshall for hits on Panthers quarterback Cam Newton during last week's game, according to reports. Stewart was docked $18,231 for roughing the passer and Marshall was fined $24,309, under the league's fines schedule this season. "I'm not going to change the way I play the game," Stewart said. Newton said Wednesday he felt "great'' and didn't want to dwell on the hits. "My job is to win football games, not lobby for my health," Newton said. LYNCH, rice HALL CANDIDATEs: Former Bucs John Lynch (safety) and Simeon Rice (defensive end) are back on the ballot among 94 candidates for the Pro Football Hall of Fame class of 2017. Notable first-timers include LaDainian Tomlinson, Jason Taylor and Donovan McNabb. Jimmy Johnson is a coaching candidate. CHARGERS: Defensive end Joey Bosa, the No. 3 overall pick, missed practice with a hamstring injury. PATRIOTS: Linebacker Dont'a Hightower did not practice because of a knee injury and tight end Ron Gronkowski (hamstring) was limited.