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X-ray Glass Represents a Remarkable and Valuable Breakthrough

X-ray Glass Represents a Remarkable and Valuable Breakthrough

Date posted: January 25, 2016 // Glass

Those who may recall the days of the cold war, and perhaps the wholesale testing of atomic weapons that accompanied this era, will be well aware of the potential dangers of ionising radiation. In Europe and the US particularly, the threat of a nuclear war was met by the construction of bunkers buried beneath metres of concrete, as a means to protect their occupants form deadly gamma rays. Even in the hospitals of that time, the radiography departments were constructed of lead lined concrete walls containing small windows with the thickness of a brick, all of which emphasised the dangers of exposure to radiation, even when employed for peaceful purposes.

Today, however, patients who may require an X-ray will enter a cubicle that is constructed largely of glass walls, with no evidence of either lead or thick concrete to be seen. The transformation has served to make the entire experience of the patient a more present and less threatening one, while the vastly improved visibility has also made the task of watching over them both easier and far more efficient for the radiographer.

As for the technicians who are tasked with managing nuclear power stations or working in research laboratories where radioactive isotopes are in use and pose an ever-present health risk, this new breed of glazing is now serving to keep them safe. So how is it possible for a sheet of material that is totally transparent just millimetres thick to provide the same level of protection as a sheet of lead or a concrete wall?

It may come as something of a surprise to learn that the secret of X-ray resistant glass lies in the fact that it contains substantial quantities of lead although not, of course, in its metallic form. The element has been used in relatively small quantities for centuries in the manufacture of certain glass items and is responsible for the beauty of the elegant crystal decanters and goblets that many like to show off on special occasions.

To block the passage of ionising radiation, however, the amount of lead or other suitable heavy metal that is added needs to be markedly higher. While the crystal decanters mentioned earlier are likely to contain around 25 to 30 percent lead in the form of its oxide, to provide protection against radiation, the recommended figure for effective X-ray glass structures is between 60 and 65 percent or more.

The dense nature of lead and other heavy metals, such as barium, is due to the fact that they possess a large number of protons. These in turn require an equal number of negatively-charged electrons in order to maintain the element’s neutrality and it is these that act to disperse the various forms of ionising radiation, against which a given installation may be required to provide protection.

Despite this seemingly, rather high metal content, however, windows, doors and partitions, when glazed with this type of material, retain better than 85 percent of their ability to transmit visible light and with no discernible distortion. Schott RD 50® is a world-class product in this category and meets all of the international standards applicable to X-ray glass used in medical, technical and research applications throughout South Africa and available from us at Labotec Industrial Technologies.