Since the XRF analyzer contains a sealed source of radioactivity, lead inspectors must handle the analyzer with great care. The radiation source is held in a metal capsule with a beryllium or thin stainless-steel window. Thus, the emissions from this source are shielded to minimize the operator’s exposure.
When the instrument is properly used, the radiation exposure is minimal. However, the operator must be fully aware of the proper operation of the instrument and the potential for radiation exposure. This discussion is not intended to be alarming. Rather, it should encourage inspectors to take the use of the instrument very seriously.
Basic common-sense dictates that the inspector adhere to the following rules of operation:
· No one should operate an XRF analyzer until they have received thorough training.
· Always handle the analyzer carefully, since some radiation is give off even when the instrument is not in use.
· Never point the shutter of an XRF analyzer at yourself or any other person. When the XRF device is used on a wall that adjoins another room or dwelling (such as an apartment of other multiple unit dwelling), the inspector must check to be certain that no one is in the adjoining space. X rays, and especially gamma rays, can go through solid objects like wood or plaster.
· Under no circumstances should the XRF analyzer be positioned in such a way that you expose your eyes or genitals to direct radiation from the instrument.
· Never open the shutter unless testing a surface.
· The XRF instrument must be in your control at all times, whether in direct sight or in an area designated secure by the company’s radiation safety officer (RSO). The lead inspector is responsible for the security of the radioactive source.
· Children are likely to be curious about a device that, in some cases, resembles a gun and is used in their surroundings. Therefore, if children are in the unit, the lead inspector or another trained person must maintain constant control over the analyzer so that children or others do not touch or tamper with the device in any way.
· If an XRF analyzer is lost, it must be reported immediately to state authorities.
Radiation is pervasive in our environment. Every person on earth is exposed to cosmic radiation, although people living in different parts of the world experience different intensities of such radiation. While one might initially believe that all radiation is harmful, there are many very important beneficial uses of radiation. For example, radiation is used for medical and dental diagnosis. These exposure to radiation gave been carefully studied and analyzed to ensure that they are well below levels that might be harmful to a human being.
There is an overriding principle of radiation safety called ALARA.
As
Low
As
Reasonably
Achievable
The basic principle of radiation safety involves accepting the fact that all exposure to radiation cannot be eliminated. Exposure to radiation is affected by three important factors:
· Time
· Distance
· Shielding
The longer the exposure time to the radiation, the more chance there is of damage to human tissues. However, a very large dose over a short period of time is generally considered more damaging than the same cumulative dose of radiation spread out over a very long time.
The distance from the radioactive source is a second factor that affects radiation exposure. The intensity of radiation diminishes very quickly with the distance between the person and the radiation source. The intensity is reduced by the square of the distance from the source.
Thus, a person who is 10 feet from the source will receive one one-hundredth the exposure compared to 1 foot from the source (10² = 100, vs. 1² = 1). Therefore, distance in your best friend when it comes to minimizing exposure.
Finally, shielding can be one means of reducing exposure for any type of radiation. If a dense substance, such as lead or concrete, is placed between the X ray source and an exposed individual, much of the radiation is absorbed by the barrier. This is why, for example, patients receiving dental X rays have their bodies shielded with a lead blanket.
Understanding how these three factors affect the amount of radiation to which a person may be exposed can assist lead-based paint inspectors in complying with the basic safety procedures in using XRF analyzers. In the XRF analyzers currently acceptable for lead-based paint testing, either a trigger or a key opens a shutter that allows the radiation to escape. Even with the shutter closed, a very small amount of radiation is emitted. Therefore, if the instrument is not in use, inspectors should keep it in its storage case (which provides additional shielding and distance). When the inspector is at the office, the XRF should always be stored at a safe distance and in its storage case.
Comments