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TLD Dosimeter vs OSL Dosimeter

Our current industrial environment has brought technological equipment in certain fields of work that can pose deadly dangers to workers and employees within the workplace. Workers working in nuclear power plants, doctors working in hospitals, or researchers working in research facilities are constantly exposed to radiation. If the levels of radiation that are being absorbed in individuals within the workplace are not measured and controlled, people could face detrimental consequences related to tNheir health, and more specifically, to their organs.

Effective Dose Radiation

Ways in which workers and employees are exposed to ionizing radiation include through the use of X-ray equipment in hospitals, or radiation emissions from radioactive substances. How, where, and the level that these workers and employees should be protected, is quite a complicated matter. For this reason, authorities have created a system of protection to measure different dimensions of radiation. These doses are not measured quantifiably, rather, a dose of radiation depends on the length of the radiation exposure, on the intensity of the radiation, and lastly, on the sensitivity levels of a person’s skin.

 

The effective dose of radiation, is a radiation dose that is used to assess the potential for long-term consequences that radiation exposure may pose on an individual during his or her future. Effective dose radiation is a value that is measured and calculated in mSv units. Effective dose radiation takes three factors into account. 

 

The first factor is each human organ’s sensitivity levels to radiation; this is important because each human organ will react differently to different levels of radiation. Some organs will be more sensitive, while others will be less sensitive. An example of this, is that the human chest is less sensitive to radiation, than the human head is. The second factor is the level of radiation that is absorbed by the human organs. The third factor is related to the level of harm that the exposed radiation can pose on the human organs. For this reason, effective dose radiation is not intended to apply to a specific individual or patient. 

 

“I often ask the question: “How many times higher do you think the radiation background levels are today compared to 30, 40, 50 years ago?” Once there was a very brave man who answered: “100 times higher.” In fact, it is one million billion times higher!”

Olle Johansson, Department of Neuroscience, Karolinska Institute, Stockholm, Sweden.

What is a Dosimeter?

One of the most common tools that are used to control and calculate this level of radiation that individuals within the workplace are exposed to, is a dosimeter. 

 

What exactly is a dosimeter? A dosimeter is a measuring instrument that is worn by individuals who are exposed to ionizing radiation. It helps to ensure that workers and employees are receiving a safe amount of radiation throughout the day. A dosimeter typically has different tasks and properties, depending on the job an individual is conducting. 

 

Specifically, a dosimeter is are able to calculate and control the effective dose of radiation that an individual receives. This way, workers and employees are able to receive an amount of radiation that will avoid damage to their bodies, or consequences that could even be potentially deadly in nature. What a dosimeter does, more specifically, is that it informs you know of an accumulated dose that is delivered by ionizing radiation over time. A dosimeter tells you the total level of radiation that someone is receiving when that level of radiation gets to a certain digit.

 

The task of the dosimeter is to essentially measure the level of radiation energy that a human body receives, over a certain period of time, in order to ensure that an individual does not exceed in receiving the statutory rad limits of radiation exposure, so that he or she is not exposed to deadly amounts of radiation. A dosimeter is important because it helps to keep the effective dose of radiation at a minimum, and to also notify an individual when to leave a radiation site. 

 

A dosimeter are greatly used to protect workers and employees from harmful levels of radiation. It is used for situations in which radiation is expected, such as in the case of occupational radiation workers. In fact, the utilization of dosimeters is mandatory in nuclear power plants. Apart from being used in situations in which radiation is expected, dosimeters are also used in situations in which radiation is unexpected. An example of such a situation is seen in the case of civilians during the aftermath of Fukushima and the Chernobyl radiological release incidents. 

 

“Before Edison’s light bulb there was very little electromagnetic radiation in our environment. The levels today are a lot higher than natural background levels and are growing rapidly because of all the new devices that emit this radiation.”

Martin Blank, Department of Physiology and Cellular Biophysics at Columbia University.

What is a TLD Dosimeter?

We have discussed dosimeters and why they are important; now we will dive into the specifics, and the types of dosimeters that are available. One type of radiation dosimeter is known as the thermoluminescent (TLD) dosimeter.

 

What is a TLD dosimeter? A TLD dosimeter is used to measure the ionizing exposure of radiation. The way that a TLD dosimeter measures this exposure, is through a TLD crystal that is embedded within its detector, this TLD crystal most commonly being either a LiF TLD crystal, or a CaD2 TLD crystal. This crystal emits a visible light when it is heated by radiation, and the more radiation exposure that the TLD crystal receives, the more intense the light that the TLD crystal emits will be. The intensity of this visible light is exactly what the TLD dosimeter measures, in order to calculate the ionizing radiation exposure that the individual is surrounded by.

 

“Extremely low-frequency radiation has very long wavelengths (on the order of a million meters or more) and frequencies in the range of 100 Hertz or cycles per second or less. Radio frequencies have wavelengths of between 1 and 100 meters and frequencies in the range of 1 million to 100 million Hertz. Microwaves that we use to heat food have wavelengths that are about 1 hundredth of a meter long and have frequencies of about 2.5 billion Hertz.”

Martin Blank, Department of Physiology and Cellular Biophysics at Columbia University.

Types of TLD Dosimeters

Now that we have spoken about what a TLD dosimeter is and how it works, let’s talk about some of the different types of TLD dosimeters, how they work, and their purpose.

TLD Dosimeter Badge

A TLD Dosimeter Badge, is one of the most common types of TLD dosimeters that are used by professionals. This type of TLD dosimeter is mostly seen in use for monitoring the beta and gamma radiation that is emitted from x-ray machines. TLD dosimeter badges are extremely important for professionals who are operating cabinet x-ray systems, x-ray fluorescence equipment, and x-ray diffraction equipment. TLD dosimeter radiation badges are also a must for pregnant women workers who are in lab settings in which energetic beta emitters, gamma emitters and x-ray radiation emitters are in use. These badges provide a tangible exposure record.

TLD Dosimeter Bracelet

A TLD Dosimeter Bracelet, is especially important for professionals who use their hands and fingers a great amount while working in settings with exposure to radiation. TLD dosimeter bracelets are usually used in the mail processing industry, in medical environments, and in industrial facilities. What a TLD dosimeter does, is that it monitors beta, gamma, and x-ray radiation exposure.

TLD Ring Dosimeter

A TLD Ring Dosimeter, like a TLD Dosimeter Bracelet, is essential for professionals who work in radiation exposure settings in which their hands and fingers are especially in use. They come in especially handy in cardiac catheterization (cath) labs and in mail processing facilities. TLD ring dosimeters make it easy to use for both extremity monitoring circumstances, and for personal dosimetry.

TLD Dosimeter Pros and Cons

TLD Dosimeter Pros

Measure Great Ranges of Radiation Doses

A great advantage of the thermoluminescent (TLD) dosimeter is that it is able to measure a great range of radiation doses. 

Reusable

One of the biggest TLD dosimeter pros, is that TLD dosimeters is that they are easily reusable. Once a TLD dosimeter has been used, it is automatically zeroed after it had been read, and ready for use once again.

Easy to Use

TLD dosimeters are also easily reusable. *Doses from TLDs may be easily obtained.TTLD dosimeters also do not have to be sent to a specific place for development, as they are able to be read with ease on site. 

TLD Dosimeter Cons

Can Only Be Read Once

One of the downsides that comes with using a TLD dosimeter is that it can only be read one time. A TLD dosimeter reading can be used multiple times; however, they cannot be read more than once, after the TLD dosimeter has been used. This occurs because TLD is “zeroed” as a result of the readout process. 

What is an OSL Dosimeter?

What is an optically stimulated luminescence (OSL) dosimeter? An OSL dosimeter is an alternative to the thermoluminescent (TLD) dosimeter. Like in the case of a TLD dosimeter, an OSL dosimeter is made from materials that are similar to a TLD dosimeter. The materials that are used to create a TLD dosimeter are similar to the materials that are used to create an OSL dosimeter because they are composed of crystalline solids. These crystalline solids are used to determine the effective dosage of radiation. OSL dosimeters are commonly used for personnel dosimetry, just are TLD dosimeters are. OSL dosimeters are suitable for being used for remorse dosimetry, and they provide users with accurate dosimetric measurements concerning radiation levels. 

 

The essential difference between a TLD dosimeter and an OSL dosimeter regarding the way that each dosimeter works, is that a TLD dosimeter requires heat in order to function, whereas and OSL dosimeter only requires optical stimulation. An OSL dosimeter uses aluminum oxide (AI203) in order to absorb X-ray energy, release it, and measure the precise dose of ionizing radiation that is received.

OSL Dosimeter Pros and Cons

OSL Dosimeter Pros

Simplified Design

OSL dosimeters are very simple in terms of their design. One reason for this is that OSL dosimeter readings to not get affected by your environmental setting, and they can easily be read at room temperature. The reading will not be faded or altered unless the OSL dosimeter is exposed to extreme temperatures. OSL dosimeters will also not require annealing for readings.

Can be Read Multiple Times

One of the greatest OSL dosimeters pros is that it is able to be read a number of times. This is an advantage for OSL dosimeters, differing from TLD dosimeters, which can only be read once. A second reading of the dosage of radiation through an OSL dosimeter may only have a very small one percent difference in comparison to its first reading. For this reason, OSL dosimeters are archived for a good number of years.

Imaging Capabilities

Professionals are able to deposit OSL powders in thin layers in order to create 2D detectors that have imaging capabilities that are similar to those seen in film. This process is something that makes OSL dosimeters stand out.

OSL Dosimeter Cons

Cost

On average, OSL dosimeters are more expensive to use than TLD dosimeters are. Their higher cost makes this to be one of the OSL dosimeters cons.

Uncertainties

Because OSL dosimeter readings are not affected by varying external temperatures, some professionals are uncertain when it comes to TLD dosimeters and their validity regarding the reporting of small doses of one thousandth of a rem, known as millirem (mrem) doses. 

“Radiation has properties of both God and Satan. Like God as the correct exposures give excellent health. Like Satan because too little or too much will make you sick and may lead to disease and premature death.” 

Steven Magee

 

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