Passive Dosimeters

Portable dosimeters for monitoring of exposed people

Individual passive dosimeters
The port and the reading of a dosimeter are individualized. The sensor itself is in a box that contained all the information that can identify the holder (name, department, institution), the use and wearing period. Among the more common passive are the OSL (Optically Stimulated Luminescence) like the InLight model of LCIE Landauer that ensures the production and follow-up..
LCIE Landauer

Dosimeters called passive are dosimeters that do not need an external source of energy to operate. They are integrating dosimeters, that is to say they do not give an estimate of an overall dose. They do not normally allow estimating maximum instantaneous doses.

They are regulatory dosimeters that must be worn on the chest by a worker that may be exposed to ionizing radiation. Extremity dosimeters are also recommended when hands, for example, would be particularly exposed to radiation.

For this reason, they tend to be replaced by active dosimeters, but they retain a place in the general monitoring of large staffs.

The cycle of monitoring dosimeters
Monitoring of personal exposure to radiations (nuclear power plants, hospitals, etc.) requires an individualized management of dosimeters, as shown by the example of “InLight” OSL dosimeters of LCIE Landauer company. After having been worn, the dosimeter is read and analyzed. Results are recorded and forwarded to the appropriate physician. OSL dosimeter reading is not destructive and dosimeter can be returned to the establishment of the worker to be used again.
LCIE Landauer
There are dosimeters specific for X-rays, beta rays, and gamma rays. There are also dosimeters for neutrons.

The worker wears the passive dosimeter for a monthly or quarterly period. After this period, the dosimeter is read and analyzed by an accredited laboratory. The results are recorded and sent to the doctor. The data is then transmitted to the central database managed by the supervisory authority.

Passive dosimeters were the first to be developed and were initially derived from photographic techniques, the same ones that led to the discovery of radioactivity by Becquerel in 1896. These dosimeters, today more commonly called dosifilms, tend to disappear owing to changes in regulations and the incoming demise of silver film.

The dosifilms are gradually replaced by dosimeters using more efficient and modern technologies measuring the light emission or luminescence of the irradiated detector. The technologies used for measuring luminescence are OSL (Optically Stimulated Luminescence), TLD (Thermo Luminescence) and RPL (Radio Photo Luminescence). The luminescence is triggered by a light flash in the case of the OSL and RPL and heating for TLD.

The OSL and TLD are, to date, passive dosimetry techniques recognized by the French legislation together with the dosifilms dosimeters.

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