Just as a note, I had an upper GI tract study done with barium sulfate about fifteen years ago to diagnose a hiatal hernia. They showed me a clear X-ray video of my swallowing and the pouch in front of my stomach that was causing my reflux and pain. For such a simple test, it's a great visualizer of stomach problems.
(The next two bowel movements I had were literally like lead bricks. If you want to mine more barium, I'd say check the sewers.)
I expect that without barium sulfate, the upper GI study will be replaced by endoscopy, where they put a camera on a tube down your throat to video the stomach from the inside. I've had that procedure done also. It's more invasive, more expensive, and requires general anesthetic.