What is dosimetry? Dosimetry is the process of measuring radiation. Multiple instruments are available that detect and measure the presence of radiation found in a laboratory, handheld, or worn, like a dosimeter badge or ring from RadiationSafety.com.  

When ionizing radiation loosens electrons, phosphor crystals in a dosimeter or dosimetry badge capture and store them. When those crystals are exposed to heat, they emit light as the electrons are released from the crystals, which illuminates a light on a dosimeter badge, band, or ring. That light is later measured and processed to provide an accurate amount of radiation to which the dosimeter was exposed. When the dosimeter badge, band, or ring is worn over a period of time, anywhere from one to three months, the crystals can then be used to determine how much exposure the wearer has had over that time period. This process is known as dosimetry.dosimeter badge OSL x-ray safety

A TLD dosimeter, or thermoluminescent dosimeter, is a passive radiation dosimeter and works by measuring ionizing radiation. Ionizing radiation is caused by X-rays, gamma rays, beta particles, alpha particles, and other radioactive isotopes that carry enough energy to free electrons from their orbit around normally stable molecules. While this can cause damage to cells in living tissue, it also can be captured and measured in a well-designed environment, like in a dosimetry badge. In addition, ionizing radiation causes damage over time, so it is essential to monitor, limit and control how much a person is exposed to. 

Invented by Professor Farringon Daniels of the University of Wisconsin-Madison in 1954, the TLD dosimeter requires heat to function. They are most useful for situations where information about radiation amounts needs to be precise but is not required immediately. TLD dosimeters can measure accumulated dosages to monitor potential health impact. 

Active Vs. Passive Dosimetry

As previously mentioned, TLD dosimeters are passive dosimeters, meaning they can operate without any external energy source and do not immediately provide radiation dosage readouts. Active dosimeters, on the other hand, require power and energy to operate and can be read in real-time. Some of our competitors offer an active dosimeter that a high failure rate. When purchasing, get in writing what is their published failure rate for their dosimeter. 

Pros and Cons of TLD Dosimeters


  • TLD dosimeters measure a large range of doses over a period of time
  • TLD dosimeters may have a lower cost than other dosmeters.


  • TLD dosimeters require heat to function.
  • Only one dose can be read at a time.
  • Once the dose is read, it resets the dosimeter.
  • One of the largest manufacturers of TLD badges and readers quit servicing their machines.

RadationSafety.com provides radiation badges and rings that are affordable and discreet. They utilize optically stimulated luminescence OSL technology, which is a more advanced technology than TLD dosimeters. OSL dosimeter badges are the industry standard used by the government, hospitals, labs, and companies around the world. An OSL dosimeter works similarly to a TLD dosimeter, but an OSL dosimeter only requires optical stimulation, whereas a TLD dosimeter requires heat in order to function. These small and discrete radiation badges can be worn on your lapel and are designed to detect X-rays, gamma radiation, beta particles, and neutron radiation.

Source: ​​https://www.radiation-dosimetry.org/what-is-thermoluminescent-dosimeter-tld-definition/ 


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