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Lead glass windows

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.





Fixing and joining lead sheet

Lead sheet will not support its own weight: it must be glued to a support material or at least screwed every 30 cm to stud battens. Evostik or other contact adhesive is ideal - roll or hammer the lead down to get full contact without bruising or thinning it. Large-head roofing felt nails or cheese-head screws can be used but check with the Radiation Protection Adviser as these can compromise the shielding.

Click here for a printable sheet of instructions for joining lead sheet to produce continuous protective layer.  



Darkroom doors and ventilators

A ventilator is important to extract noxious fumes from the processor. The main source of stray light entering darkrooms is usually round the door, but a tight-fitting door will prevent air entering and thus render the extractor useless. Toilet vent fans are adequate for small darkrooms but they are usually made form translucent plastic which is undesirable.

The answer is to make loose wooden baffles for the door frame and the extractor. Click here for some design hints and sketches.







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