by Radiation Detection
Radiation Exposure from Airport X-Ray Detectors?
Is radiation exposure from airport security checkpoints dangerous while using X-ray detectors? The danger of radiation exposure from X-ray detector machines is highest for individuals who work near the devices, such as security personnel or postal workers. According to the Occupational Safety and Health Administration (OSHA), workers’ maximum allowable radiation exposure dose is 5,000 millirems (mrem) per year.
Studies have shown that the radiation doses from properly maintained X-ray machines are below this limit. For example, a study conducted by the National Institute of Standards and Technology (NIST) found that the radiation exposure from a properly functioning X-ray machine was only 0.5 mrem per hour at a distance of one meter.
It is important to note that the danger of X-ray radiation exposure is much lower for individuals not close to them. For example, the Transportation Security Administration (TSA) has stated that the X-ray radiation exposure from their X-ray detectors is “minuscule” and poses no health risk to passengers. While there is potential radiation exposure from X-ray detectors or scanners, the risk is minimal if the machines are properly maintained and appropriately operated according to OSHA and ALARA recommendations.
Therefore, for the general public, it is most likely that there is not a significant risk of radiation exposure from airport X-ray detectors or security scanners in other facilities. However, workers near these machines should take appropriate precautions to limit exposure. They should also consider wearing dosimeter badges and dosimeter extremity rings. As always, check with your radiation safety officer (RSO).
References:
– Occupational Safety and Health Administration. (n.d.). Ionizing Radiation. Retrieved from https://www.osha.gov/– National Institute of Standards and Technology. (2013). Radiation Safety of X-ray Security Screening Systems. Retrieved from https://www.nist.gov– Transportation Security Administration. (n.d.). Advanced Imaging Technology. Retrieved from https://www.tsa.gov
by Radiation Detection
Benefits of OSL Dosimeters
OSL (Optically Stimulated Luminescence) dosimeters are known for their exceptional durability. These dosimeters are designed to withstand various challenging conditions with minimal damage. They are highly resistant to temperature extremes, whether it is exposure to high or low temperatures or sudden fluctuations in temperature. Unlike TLD (Thermoluminescent Dosimeter) crystals, OSL badges are significantly less prone to damage from moisture and humidity. One of the impressive features of OSL badges is their ruggedness. Dropping an OSL dosimeter usually does not lead to any damage, as long as the plastic case remains intact. These dosimeters are also capable of enduring high humidity levels, extreme heat and cold, and sudden temperature changes. OSL badges can even be submerged in water for long periods of time, which means they can handle being accidentally put through a washer and dryer without being affected. On the other hand, TLD dosimeters are comparatively more delicate. They are more susceptible to damage caused by high or low temperatures, sudden changes in temperature, moisture, and humidity. If a TLD dosimeter becomes damaged, it generally needs to be replaced. Over time, the costs of these replacements can accumulate, which can be a significant consideration. One important aspect to note is that there is a risk associated with wearing a damaged dosimeter. If an employee continues to wear a damaged dosimeter, there is a possibility that their doses will not be accurately recorded. This could potentially lead to inaccurate monitoring and evaluation of their radiation exposure. Therefore, when it comes to durability, OSL dosimeters are generally considered to be much more resilient and durable compared to TLD dosimeters. Their ability to withstand various harsh conditions and potential accidents makes them a reliable choice for radiation monitoring.
The read method for OSL (Optically Stimulated Luminescence) dosimeters involves using light in a non-destructive manner. In contrast, TLD (Thermoluminescent Dosimetry) dosimeters are read using heat in a destructive process. It should be noted that reading a TLD dosimeter releases the trapped energy, resetting the crystal back to zero and making it impossible to re-read.
Lower Limits of Radiation Detection
The lower limit of detection (LLD) is a crucial factor when selecting a dosimeter, as it determines the minimum level of radiation exposure that the dosimeter can accurately measure. This is particularly important in ensuring that any potentially harmful doses of radiation are not missed. Optically Stimulated Luminescence (OSL) dosimeters and Thermoluminescent Dosimeters (TLD) have specific considerations regarding their LLD. OSL dosimeters typically have a lower LLD compared to TLD dosimeters. OSL dosimeters can have an LLD as low as 1-10 μSv (microsievert), while TLD dosimeters usually have a higher LLD, often above 10 μSv. A lower LLD is advantageous because it reduces the likelihood of missing even small doses of radiation during a given wear period. This is important for adhering to the As Low As Reasonably Achievable (ALARA) principle, which aims to minimize radiation exposure to the lowest possible level. To illustrate the significance of a lower LLD, let’s consider an example. Suppose an x-ray technician wears a dosimeter with an LLD of 10 μSv and is exposed to 9 μSv of radiation each month. If the reported dose is determined solely by the dosimeter’s LLD, it would be labeled as “minimal” each month. However, over a year, the accumulated missed dose could reach up to 100 μSv (9 μSv * 12 months = 108 μSv). This accumulation of missed doses might eventually exceed the ALARA limits, potentially posing health risks. It’s important to note that while some dosimeters may advertise an LLD below 10 μSv, particularly in the case of TLD dosimeters, the precision of measurement at such low levels of exposure tends to decline. This suggests that relying on dosimeters with lower LLDs might yield less accurate results for doses below 10 μSv under routine conditions. Therefore, caution should be exercised when considering dosimeters with excessively low LLDs. In summary, the LLD for OSL dosimeters can be as low as 1-10 μSv, while for TLD dosimeters, it is typically higher, often above 10 μSv. A lower LLD is important in accurately measuring radiation exposure and preventing potential health risks from missed doses. However, it’s essential to consider the precision of dosimeters at very low dose levels when selecting devices with particularly low LLDs.
