The tube (the part that you aim at the body) is not large enough to house the spinning anode and the cathode. While the plug in models are a lot smaller, they are still larger than this because you need to have a step up transformer in the unit large enough to bring the Voltage to KV levels. Also, plug in models are very inconvenient, especially in an emergency situation, ie; breaking every bone in you body! This would be an absolute hazard in the ER department.

Maybe in the future, with advancements in battery materials, as well as maybe other, high melting point materials such as tungsten may be found. Also, the imaging plates/detectors will likely become much more sensitive making this more plausible.

One last thing, you need to have a License to own such equipment for use on people, also an actual Radiologist legally qualified to interpret the images.

If this is possible now, it would be so expensive it would completely outweigh the advantage the equipment to the point that no one could afford to buy it.