Teaching MRI and x-rays

For my practicum class we're doing some peer teaching before we go out into the schools, and they want us to focus on science and technology because they've been told that we're not as strong in that.  I would say that's pretty strong for me, but I am an AT so there's the big difference.  Anyways, we have 10-12 minutes to do a mini lesson and I chose medical imaging, which I've decided to focus on x-rays and MRIs. I feel like I could write a 90 minute lesson easily going through the history and then teaching them how to read the different images and image what life was like if you were injured in the time before imaging.  But I don't know how to do it in 10 minutes and what they should get out of 10 minutes, and then how to make it interactive and fun.  I think that MRI is more interesting than x-rays, but maybe I should just focus on simple and do x-rays and leave it at that.  Gah!