The lead lined door is designed to protect against the x-ray radiation with a lead plate filled inside of the door body as well as a  viewing window with lead glass, this type of door is usually applied to the x-ray room or CT room in hospitals.

The normal thickness of the lead plate is about 0.5 to 2.0mm, to TSTC, the recommended thickness of the lead board is 3.0mm for most,  we can also adopt the lead plate with some more thickness, however, considering the big density of the lead, it will bring potential loss to the electronic parts and the mechanical parts of the door, because the door body is much more heavy with the thick lead .

To more details, please check the related document in our website with the name "About The Lead Equivalent and Thickness of Lead Glass" .