I appreciate the kind advice, since you are correct that Med Phys is a rewarding field for many. However, I'm already more than familiar with Med Phys, since that's most of the "boring day job" I use to pay the bills. I was on the design team for some of the most widely used devices in the field. Unfortunately, as a field of applied physics, it is the epitome of slow steady progress with almost no real breakthroughs. There's nothing wrong with that, especially when it helps people, but I'd prefer to work on things with the potential for big breakthroughs. So I work on the boring stuff during the day, and do mad science at night.