Can I get built in collision boxes to only detect collision in certain areas?

I think I have a way to do something like this with a custom raycasting physics system, but I think that
would take quite a while. I have points in the game world that have a radius. The game is 2D. The points and radius will create a circular area, which I want colliders to detect. Is there a way that I can check for collisions on a collider, then get the point on the collider that it collided, then check if it is within this circle area (The distance to the center point is less than the radius), then decide to ignore the collision if it is within the area. The effect I want would be a movable circular area that will stop collision inside of it. Sorry if this is a bit specific to my game, but help would be great!

 

http://docs.unity3d.com/ScriptReference/Physics2D.OverlapCircle.html

 

Oh wow, thanks this is perfect! I have no idea how this is a thing though, I didn't think that much people would want this effect. I guess it could be used for a lot of other things. Thanks!