Above are some portable scanners to give you an idea of what they are like. For reference the ones I saw were specifically GE Medical Solutions. And Kodak makes the film (Surprise! or not). From a technical point of view, portable X-ray machines are actually rather intriguing. They don't expose film that a person can read right away. Instead you shoot at a cartridge (a $400 re-usable cartridge) that you place behind a person while the are laying or sitting down. The cartridge is basically comprised of a box with a phosphor plate inside. Once the scan is acquired, you pass into a machine and it gets scanned into the hospitals PACS (picture archive effectively). Then it can be passed to radiology for reading digitally, no film running here! Also, a portable X-ray machine has a far more concentrated beam and much less scattering, so no lead coats are required, which is useful.
So I traveled the 4th floor with the tech (nice guy), and got to see how he acquired the scans. Most people are very understanding when he comes in (I think its because of all medical procedures they understand x-ray the most). The tech usually leans the patient forward, slides the plate under their chest, steps 70" back, yells "X-ray", hits a button, yells "Clear", and we are done. Its quick. The general result is below
Sometimes there are problems. Like if a doctor doesn't put in orders, but need it done 'stat'. Or if there is double-exposure. Or the patients obese. Or the patient is rotated. For that last one sometimes there nothing that can be done.