X-ray tubes, old and new, use high energy electrons that impact a metal to create the beam. Alpha and beta emission is from radioactive decay which is an entirely different phenomenon. But yes bathing your body in X-rays is bad for you
I do wonder whether this was actually an effective way to look for them. Even with modern high resolution x-ray imaging it may be difficult to see the contrast between soft tissues and diamonds since they’re both primarily carbon
South African diamond miner being x-rayed at the end of his shift to prevent theft, 1954 (lemmy.world)