This is a small xray tube and it has no window. It will probably only tolerate 10 seconds of operation before the anode starts melting and that will short the power supply. The actually efficiency of conversion of electrons to xrays is terribly low, because it depends on an electron striking the atom at a precise angle. Since matter is largely open space, the number of electrons in the beam from the cathode that are converted to xrays is tiny. Since the operating current of this tube is probably only a few tens of milliamps, the whole thing is perfectly safe. The tube can't generate enough xrays to be harmful before it melts. It's self limiting and can't hurt anyone even if they tried. I know we all love scary stories, but most real risks can be managed with a little care. For example, motor fuel, it's explosive potential is truly quite amazing. Yet we put our children into a mobile explosive carrier, drive to an airport and fling them high into the sky at over 500km per hour to go on annual holidays. Basically, we are terrible at risk perception. If we perceive a benefit (holiday) we'll put ourselves and our children in real danger. Frankly, the hammer in your garage is a far more dangerous artefact than that xray tube. Read crime statistics, more people die of hammer attacks each year than from xray exposure. Should we force everyone to store hammers in locked safes and demand every hammer in our society is registered? Will hammer users require safety training and licensing? Some risks can be managed, some not so easily, life has no guarantees, but knowledge can free us from baseless fears.