facebook og-image tag

Hello,
I am trying to dynamically generate og:image tag and place it in the header of a page. I would like to have an unique image for each page. I am trying to get this image from the content in the body of the page and populate the og:image tag. But, as the head tags are generated before even the content is being displayed on the page, is there a way to get the image from the generic content on the page and then write the og:image tag. Can this be accomplished. I have been working the sitefinity team and their support has been great, but we are not able to get to a conclusion yet, so i wanted to post in the forums and see if someone has a solution or implemented this before. i would really appreciate any suggestions!!

thank you.

Any suggestions, thank you!!