What is a Dosimeter?

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Ionizing radiation is harmful. At best, it causes radiation sickness and/or burns; at its worst, it’s fatal or is the cause of terminal cancers and other health conditions that can be fatal. Fortunately, radiation dosimeters come in various sizes and styles, but are ultimately designed to measure the levels of harmful ionizing radiation as a safety precaution.

Smaller models can be worn by those working in radioactive environments to monitor their exposure in real-time, as well as to keep track of cumulative exposure overtime, since slow and continuous exposure to low-dose ionizing radiation is as harmful – or more so – than acute, high doses in a single exposure. They are a standard tool in radioactive industries and careers, as well as in the disciplines of radiation dosimetry and radiation health physics.

What is a Dosimiter and How Does it Measure Radiation?

These devices are made using radiation sensitive materials to measure exposure to gamma radiation, x-radiation and high-energy beta radiation (such as P-32). In addition to measuring and recording whole body doses, some dosimeters are designed to measure immediate, localized, radiation exposure.

The types worn by employees or personnel working in and around ionizing radiation exposure are called radiation badges, and can be clipped onto their protective clothing. Radiation dosimeters are most commonly worn and used by those whose work puts them at risk for maximum exposure limits:

  • Occupational whole body dose limit is 5,000 millirems per year
  • Dose limit to the extremities (hands, fingers, etc.) is 50,000 millirems per year

Professionals and employees most likely to use and/or wear a radiation badge include:

  • Nuclear power plant workers
  • Radiographers
  • Physicians working in the field of radiotherapy
  • Laboratory staff using radioactive materials
  • HAZMAT teams when called to nuclear disasters and/or to investigate suspected cases of harmful occupational radiation exposure

It is important to note that while dosimeters measure radiation exposure, they do not protect the wearer from the exposure and are not considered radiation shielding.

5 Types of Radiation Dosimeters

There are five different types of radiation dosimeters.

  1. Electronic Personal Dosimeter (EPD). These personal electronic devices are most often used in scenarios where there is high dose radiation exposure, and where employees are only working within those high exposure limits for a short time. EPDs have several sophisticated functions and can be reset after taking a reading – which is recorded – for reuse.
  2. MOSFET Dosimeter. These are used as clinical dosimeters in order to measure the radiation levels of radiotherapy radiation beams. MOSFET dosimeters provide readings within extremely thin active areas and are very small in size. The dosimeter’s post radiation signals are permanently stored.
  3. Film Badge Dosimeter. These tools are designed for one-time use, after which they are no longer functional. Radiation level absorption is shown via changes in the film emulsion and is evident after the film is developed.
  4. Quartz Fiber Dosimeter (QFD). QFDs are the precursors to EFDs and are now being superseded by them. Also designed for one-time use, QFDs are charged to a high voltage and readings are taken in response to the changes in electrical charge, which is proportional to radiation exposure levels.
  5. Thermoluminescent dosimeters (TLD). This type of dosimeter uses a crystal that emits light when exposed to heat, caused by radiation exposure. The intensity of the visible light is measure, indicating the level of exposure. As with EFDs, TLDs are being used more and more in place of QFDs.

Dosimeters Are and Essential Part of Radiation Safety Programs

Ultimately, dosimeters and radiation badges are essential parts of any company’s radiation safety program, and should be used regularly, and diligently, as per manufacturer’s recommendations to keep worker’s radiation exposure well below maximum levels. Dosimeters should be used in compliance with industry best standards, as well as all the necessary radiation shielding and protective clothing products used to keep employees safe.

Interested in learning more about the types of radioactive shielding and protective clothing products available? Contact us here at Lancs Industries. We’ve created innovative, durable and proven radiation shielding products for more than four decades, and we’re always happy to work with clients to design custom products for their unique work environments and/or situations.

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