Personal dosimetry

 
 

For personal dosimetry, the standard procedure is to wear an individual whole body dosemeter on the chest. Depending on the specific requirements, this can be supplemented with a wrist, finger, eye lens or lead apron dosemeter. Some 10,000 Belgians and Dutch are currently wearing a dosemeter of the Belgian Nuclear Research Centre.

The various types of dosemeters all consist of a holder in which the dosemeter itself is inserted. Inside the dosemeter are the detectors that are sensitive to both beta and gamma rays.

The radiation dose of professionally exposed employees is usually monitored on a monthly basis, but the exchange of the dosemeter every three months is also possible. The natural background radiation is subtracted from the result.

 

Body Dosemeter

As of today, SCK•CEN offers two types of personal dosemeter. The oldest one is based on the principle of thermoluminescence (TLD). In 2017, a new type of dosemeter was brought into use, the InLight dosemeter which is based on optically stimulated luminescence (OSL). 

InLight Body Dosemeter

The InLight dosemeter detects beta radiation as well as X-rays and gamma radiation. The dosemeter is made of four active items. The 4 detectors consist of carbon doped aluminium oxide but are also positioned behind 4 different filters included in the case. These filters allow to determine the energy of the incident radiation, so that the dosemeter responds in a tissue equivalent way to all radiation energies. This dosemeter detects beta radiation as well as X-rays and gamma radiation so that it measures the depth dose Hp(10) and the surface dose Hp(0,07). One of the advantages of this dosemeter is that we can read it multiple times.

Facts & Figures: InLight dosemeter

  • Minimum detectable dose: 50 µSv
  • Measuring range: 50 µSv to 10 Sv
  • Reproducibility: 20 %
  • X-rays and gamma energy range: 12 keV to 6 MeV
  • Beta energy range: 700 keV to 2.3 MeV (expressed in max E)
  • Small and light: 7.5 cm high, 1 cm thick, 18 g

More info in our leaflet

TLD dosemeter

A body TLD consists of a holder containing three detectors. This dosemeter is sensitive to beta, X and gamma rays. Due  the various detector filters, one detector measures the depth dose Hp(10), and the other the surface dose Hp(0.07). A third detector in the dosemeter serves as a back-up.

Facts & Figures: SCK•CEN body dosemeter

  • Minimum detectable dose: 50 µSv
  • Measurement range: 50 µSv to 20 Sv
  • Reproducibility: 20 %
  • X-rays and gamma energy range: 12 keV to 6 MeV
  • Beta energy range: 500 keV to 3 MeV (expressed in Emax)
  • Small and light
    • PVC disk: 4.2 cm diameter
    • 10 mm thickness
    • 15 g
 

Finger dosimetry

If radioactive products are manipulated by hand, it may be necessary to also wear a finger and/or wrist dosemeter in addition to a body dosemeter on the chest. Like a body dosemeter, a wrist dosemeter contains three detectors. Ring dosemeters consist of a plastic ring with one single thermoluminescent detector.
When a ring or wrist dosemeter is worn, it is important that the detector is directed as much as possible towards the source of radioactivity; usually this means facing the inside of the hand or the wrist. Examples of personnel who wear finger dosemeters are operators working in a nuclear medical department or people working in glove boxes.

 

Eye lens dosimetry

The existing dose limits for the eye lens were recently made stricter. This means that it is recommended to wear an eye lens dosemeter for certain applications, for example for cardiologists who are working in an interventional cardiology department. Please contact the SCK•CEN dosimetry expert group for information in this field.

 

Lead apron dosimetry

When a lead apron is used for radiation protection, the question arises as to whether the dosemeter should be worn above or underneath the lead apron. In this case, SCK•CEN suggests double dosimetry. The person then wears a body dosemeter above as well as underneath the lead apron. For the read-out and reporting of the exposure dose, the dosimetry laboratory uses an algorithm that takes the results of both dosemeters into account.