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X-Ray Radiation Protection Windows

X-Ray Radiation Protection Windows

Date posted: January 16, 2017 // Radiation Protection Glass

The discovery of an invisible force, among the shorter wavelengths of what we now term the electromagnetic spectrum, that enabled one to photograph the bone structures normally concealed beneath muscles and other soft tissues, sparked a revolution in the diagnostic procedures of the time. Used somewhat indiscriminately to detect fractures of patients’ limbs and digits and, often, just as an entertaining demonstration, it was not too long before evidence of the less benign effects of this force began to become apparent.

The superficial effect of repeated or prolonged exposure to X-rays will often present as a reddening of the exposed skin or, in more severe cases, as serious burns. However, it is the hidden effects of this form of ionising radiation that are more worrying. These can include permanent infertility and the formation of malignant tumours. For protection of those operating the equipment, lead and concrete barriers proved effective. However, these materials lacked the transparency of windows and meant that patients could not be observed during the actual exposure.

The solution, when it was finally developed, can attribute its origins to a technology that had been in use for around four centuries, albeit for rather more trivial purposes. Invented by one George Ravenscroft, at some time during the 1600s, crystal or flint glass was easier to work by hand or machine, and had far more sparkle than conventional glass. These desirable new properties were the result of including between 24% and 32% of lead oxide in the molten mix, before it was blown or moulded.

It later became apparent that by including around double this percentage of lead or the oxides of certain other materials that have heavy nuclei, such as barium, the resulting glass becomes resistant to the passage of X-ray radiation, without any appreciable loss of transparency. This made it the ideal material to provide protection for personnel when used to provide windows through which to monitor operations. The ability to observe the actions of patients, in total safety, throughout their examination, has made it much easier for radiographers to control the process. This can help to limit the need for repeats that might increase a patient’s exposure, and the risk of a cumulative overdose.

It is, of course, this cumulative effect that poses the threat to the safety of those who operate the equipment and, in addition to the use of lead glass, it is necessary to keep a close watch on the level of each operator’s exposure during a given period. For this purpose, they are required to wear badges that record their exposure and indicate when approaching the maximum recommended levels.

Equally valid in a radiotherapy or CT scanning department, providing protection from X-rays and gamma radiation by means of lead glass windows, in combination with monitored dosimetry programmes, are basic precautions that are absolutely vital to ensure the safety of hospital staff.

Known worldwide as a manufacturer of specialised glass, Schott is the brain behind the product known as RD 50®. With 65% of its weight made up of lead oxide, it offers a maximum protection and excellent visibility with thin, lightweight panes. RD 50® and other quality Schott products are available in South Africa from LIT Africa.