Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: katieHaylor on 31/07/2017 12:37:14

Title: Can lead glass block x-rays?
Post by: katieHaylor on 31/07/2017 12:37:14
Mustafa asks:

I was wondering, can lead glass of a standard thickness entirely block out x-rays (either scattered, leaked or directly from the x-ray tube)? What percentage of the x-rays can get through?

What do you think?
Title: Re: Can lead glass block x-rays?
Post by: evan_au on 31/07/2017 19:49:43
You can't entirely block X-Rays, but you can reduce the exposure levels for radiographers to levels that are insignificant compared to natural background radiation.
Title: Re: Can lead glass block x-rays?
Post by: alancalverd on 01/08/2017 00:31:03
"Lead glass" can refer to decorative "lead crystal" which contains a significant proportion of lead but is usually very thin. We use thick glass with a high lead, zinc or barium content, specified for radiation shielding by its "lead equivalent" - the thickness of metallic lead that has the same attenuation of low-energy x-rays. Common materials are 0.5 , 1.5 or 2.5 mm lead equivalent for 100 kV x-rays, useful for reducing scattered radiation in diagnostic x-ray installations.

As Evan says, no material completely absorbs x-rays, and lead becomes less effective at high photon energies. Zinc bromide solution  has been preferred in some radiotherapy and nuclear installations, but nowadays I prefer to avoid the cost and complication of fitting transparent windows and specify CCTV instead.

If you are designing a radiation enclosure, you must consult a certified radiation protection adviser. The arithmetic is quite simple but you need to know what you are doing  and what the law says.