Getting photo src from facebook event page using facebook sdk

Hello everyone,
I need some help with facebook api
I want to get the biggest sized photo from an event page (its profile picture), using graph api or fql.
unfortunately the biggest photo which pic_big can give is 200x600, which is rather small for what i want to use.
I’ve been reading around and i found out that facebook does stores bigger sized photos in a table called photo_src http://developers.facebook.com/docs/reference/fql/photo_src/ or the source field of the photo table

So if i want to get a bigger sized photo, i have to read this table using a photo_id.
However, i find it pretty hard to get an event’s profile photo ID, i’ve tried many ways which have failed.

Is there anyone who knows how can i achieve this?

thanks.