Those things are neat! I have one kicking around here that is actually COLOR, using a beam-index tube. 1" diagonal CRT. If I could get a second matching unit, it might make a good start on a homebrew VR helmet.
As far as radiation hazard, my understanding is that X-rays are generated by any tube (by electrons hitting the plate) But until the accelerating voltage hits 10-12kV or so, the X-rays aren't energetic enough to penetrate the glass envelope. You're pretty safe at 4-6 kV.