Hanson - City's top scorer so far this season - has started the club's last two games on the bench following a recent thigh problem.
The 27 year-old scored during a midweek behind-closed-doors friendly at Sheffield United, however, and Parkinson has revealed that the striker's hard work recently on the training ground has given him food for thought.
Parkinson said: "We always have good games against Sheffield United because they field strong sides.
"Hans (James Hanson) got his goal in the game, which I was pleased with.
"There's no doubt about it, he is pushing for a place in the team this Saturday.
"He is our top scorer and he is banging on the door to get back in that team because he wants to play.
"The way he showed that to me is the way he has trained and the way he played against Sheffield United on Tuesday."
One player definitely not involved against Orient will be Filipe Morais though.
The Portuguese winger damaged his shoulder during the Gillingham match last time out - although City are hopeful he will be back for next Sunday's F.A Cup tie with Dartford or the trip to Chesterfield the weekend after that.
"He has been running today (Friday) - he is determined to get back fit as soon as possible.
"When you have Filipe's determination, you normally find that the recovery time is speeded up.
"It look likes this Saturday will be too soon for him but he is pushing as hard as he can for next weekend.
"He is a player who is currently at the top of his game. The good news is then that because he is running today, we can still keep on top of his fitness while his shoulder recovers."
Matthew Dolan is another player not available to Parkinson after the midfielder penned a loan deal with Hartlepool United this Thursday.
Parkinson said: "Matty wanted to go.
"I would have personally liked to have kept Matty with us because I wanted to keep the squad together through the busy period of the next month or so at least.
"He has been frustrated about not playing though, and he is a good lad and we wanted to do right by him.
"He has been unfortunate not to play more so far this season. He was in a position to play during pre-season but the form of Jason Kennedy saw him in the team ahead of him come the start of the season.
"He did great for Hartlepool last season. It is in difficult circumstances he goes to them at the moment given their low current position in League 2 but he is a player who they feel can give them a lift.
"He'll come back to us after the Christmas period fit and ready to fight for his place once again."