The lead glass with 2 units of lead equivalents, mainly depends on whether it is Chinese domestic lead glass or imported lead glass. Generally speaking, 10mm thick domestic lead glass is at or above 2mmpb under 120kV X-ray intensity, while 6mm thick imported lead glass could reach or above 2mmpb under 120kV X-ray intensity irradiation.

Lead equivalent refers to the ability to protect against radiation. As many substances can block radiation, and lead has a good effect and is most commonly used, therefore, the protective ability of lead is used as a quantitative standard, which called lead equivalent .

The common thickness of radiation resistant lead glass is 10mm, 12mm, 15mm, 18mm and 20mm. 10mm lead glass correspond to 2 lead equivalents, 12mm correspond to 2.5 lead equivalents, 15 mm correspond to 3 lead equivalents, 18mm correspond to 4 lead equivalents, and 20mm lead glass correspond to 4.5 lead equivalents.

Generally, 3 to 4 lead equivalents are used in CT rooms, while 2 to 3 lead equivalents are used in dental hospitals.

For lead plates(lead board ), 1mm thick pure lead plates are 1 lead equivalent, and 2mm thick pure lead plates are 2 lead equivalent.