Is there more of a demand for Sonographers or Physical Therapist Assistants?

I graduated with a bachelor's but am looking to go back to school for a medical profession so that I can actually find a job. I live in a relatively low populated area (around 30,000), and am wondering if diagonostic sonographers or physical therapist assistants are more in demand. Also, which do you think is a more rewarding career? I am interested in learning about cardiac sonography as my father died of a heart attack at a young age and I think this would be rewarding to me. I have also heard that Physical Therapy is a rather laid back field, which is something I sorta need because I can become stressed easily.