[old_tv_nut]

The amount of X-rays generated by an electron beam is highly dependent on the value of the high voltage. The X-ray scare and the 6-foot suggestion came about with color sets that used defective high voltage regulator tubes with inadequate shielding for those tubes. The defective tubes had the internal shielding elements crooked, allowing X rays to escape. Even then, the concern was for long term effects, not immediate danger, and the industry had a mass campaign to replace defective tubes. The picture tubes themselves have always included lead in the glass to shield against X-rays (or external shielding glass in earlier sets). You may find early sets with warnings to the technician about being exposed to the back of a CRT with an open cabinet.