Tuukka Rask has been diagnosed with a concussion, the Bruins announced, and is out for tonight's game against the Vancouver Canucks at TD Garden, David Backes will be making his season debut after a bout with diverticulitis cost him the first five games and Patrice Bergeron, who has not played yet this season because of a lower body, will be a game-time decision. The Bruins said in a statement released Thursday afternoon they are following the NHL's concussion protocol on Rask, who left the ice woozy after a hard collision with Anders Bjork in Wednesday's practice. Bjork was flying down the right wing and tried to cut across the crease and take the puck to his forehand. It's possible Bjork got bumped from behind before colliding with Rask, who took the full brunt of the impact. How long Rask will be on the shelf is not yet known. Anton Khudobin will get the start in net tonight and coach Bruce Cassidy said Zane McIntyre will be brought up from Providence to back him up.