structural biology - Can protein structure be determined by X-Ray Diffraction in a single image?

Not by analysing a single protein. There is work with x-ray lasers.

You have to take a simultaneous image of millions of proteins and use that to get a structure. It's not quite prime time. People are also doing this with electron beams in electron microscopes.

These methods will reconstruct 3D models of the molecules, sometimes in states which cannot be obtained from crystallography. Examples being the structure of the many megadalton nuclear pore complex, and the f-actin fiber. The classic study is 3d model of bacteriorhodopsin, the first membrane protein structure which was at molecular resolution (this was a crystalline sample though).

While in principle, it sounds much simpler - get a pure sample of your protein, or complex and freeze it down and zap it with an Xray or Electron beam, its a lot more work to reconstruct the image and can take as long or longer than getting an x-ray structure. The resolution is also usually poor as the crystal will reinforce coherence, that is all the proteins are aligned in the same way and have close to the same 3d shape in a crystal.