Salaam Mahmood,

I understand the disappointment, but don't fret too much. Look at the bright side, toward which I see two positives. It was your original idea, not plaegarism, and great minds think alike.

As for your dissertation, you absolutely DO, make that DO, make that DO want to include this in your dissertation. Make a point to emphasize that you developed this originally, being certain to describe in detail the development/thought process you went through to realize this idea, and also taking care to disclose right up front that upon researching you discovered that someone else had done this before you. You won't get credit for the invention, but you should get credit for coming up with it on your own (and for being honest enough not to try and steal credit to which you weren't due).

Good luck,

Joe