Lead glass is softer and denser than ordinary window glass. It is supplied in various "lead equivalent" thicknesses: the actual thickness may be five or more times the lead equivalent. It is more expensive than other shielding materials (lead, concrete) so for small x-ray practices it is common to fit a small lead-glass window at eye level as an insert into a lead-ply sandwich panel that protects the operator.
It can be purchased new, cut to any size, from regular radiation protection suppliers (Wardray-Premise, Envirotect, etc) but reclaimed material is available from dealers in used x-ray equipment (e.g. Southex, PLH). If you use reclaimed glass, make sure the supplier labels it with the lead equivalent (e.g. ">1.5mm LE @ 150 kV Supplied by J Smith & Co").
Any fabricated radiation barrier should bear a permanent label showing its protective value. This is usually shown as actual lead and lead equivalent, e.g. "Code 4 lead with > 2mm LE glass".
It is essential to fit a lead glass window correctly, to ensure that there are no gaps in the protection. Click here for a simple method of installing a window in a lead/ply sandwich.