By definition, dosimeter for radiation are instruments that measure the radiation received by a person or object. They are used for radiation protection and operational dosimetry.
Summarize this article with :
A dosimeter measures doses and the amount of radiation energy absorbed by matter. This type of instrument uses electronics to detect the particles, emitters or rays of radiation that pass through it.
Operational or active dosimetry can be used for the radiation protection of workers exposed to ionizing radiation in their working environment. It is also used for environmental site monitoring.
Operational dosimeters are small electronic devices that measure the amount of radiation a person is exposed to during the working day.
This can help them determine whether they need to take precautions for their health and safety.
Operational dosimeters are also useful for monitoring the amount of radiation absorbed by personnel during an accident or other event involving high levels of exposure.
Operational dosimetry allows you to :
Unlike the passive or delayed-reading dosimeter, the operational dosimeter doesn't need to be exposed to radiation to work.
It uses an internal power source, such as a small battery, so it can measure even when there is no detectable radiation around it.
An operational dosimeter measures the radiation dose by detecting and counting the number of ionizations in their solid-state detector.
This is done using an array of silicon photodiodes, which produce a measurable electric current when struck by photons.
When a gamma photon interacts with the silicon detector, it generates an electron-hole pair.
By applying a reverse bias to the silicon diode, a depletion layer with extremely weak electrons is created, and taken as the detection assembly.
From a simplistic point of view, the silicon detector acts like a solid-state ionization chamber operating in pulse mode.
By optimizing the composite metal filter shielding and electrical thresholds (to minimize noise), the energy response can be flattened.
A dose-equivalent response is obtained by counting detector pulses.
X-rays are similar to gamma rays and are detected by the silicon detector. Beta is simply a high-energy electron. The dosimeter responds to beta energy if a thin window is provided to allow it to reach the silicon detector. Neutrons interact only weakly with the silicon detector. Different materials are needed to convert them into detectable ionizing particles.
Like the passive dosimeter, the operational dosimeter measures the amount and rate of radiation exposure.
It can also be used to estimate your risk of developing cancer or other diseases.
They measure ionizing radiation, i.e. any form of energy capable of breaking the chemical bonds of molecules in living cells.
The ability of ionizing radiation to cause damage varies considerably; X-rays penetrate tissues by only a few millimeters, while heavy cosmic rays can penetrate the entire body.
Radiation exposure occurs when you are exposed in an area with ionizing particles such as alpha and beta particles, neutrons or gamma rays from radioactive substances such as uranium or plutonium.
Exposure can come from natural sources, such as radon found underground, or artificial sources, such as X-ray machines in airports or hospitals.
Operational dosimeters are the best way to measure radioactivity in real time. They offer several advantages over delayed-reading dosimetry or passive dosimetry, such as instant readout.
This makes operational dosimeters ideal for situations where workers need an immediate reading with frequent monitoring - for example, when working in high-risk areas with high exposure or contamination levels, or when spending long periods in contaminated areas (emergency response).
They feature visual and audible alarms that are triggered when the wearer's pre-selected acceptable levels are exceeded.
You must wear individual dosimeters if you regularly work in a controlled zone where ionizing radiation is present.
For example, if you are :
Individual dosimetric monitoring is required in accordance with French regulations to ensure compliance with regulatory levels(article R4451-64 of the French Labor Code).
Dosimetry in the controlled zone is implemented by the Radiation Protection Advisor or Radiation Protection Competent Person in consultation with occupational medicine.
Your exposure is monitored electronically by the dosimeter, which mainly provides information on :
Workers must take care to respect the ALARA principle in order to limit their exposure.
An operational dosimeter is worn on the chest under protective clothing, using the fastening clip.
Nothing should cover it or the outside, and nothing should point outwards through the low-energy radiation window of the personal dosimeter.
The display must be oriented for easy reading in all circumstances.
Make sure you know where the dosimeter is at all times.
Detectors of radiation arre designed to be easy to use. It is nominative and individual. They are supplied ready for use. They must be adapted to the radiation present.
After switching on the dosimeter, the wearer activates it at a reading station located at the entrance to controlled areas. Check and set the alarm threshold in the menu, then don the dosimeter. The operational dosimeter lets you see the instantaneous measurement, so you can protect yourself more effectively.
The equivalent dose is the dose received by the whole body and is expressed in microSvts.
It can be broken down into two different types of dose: Hp 7 at the skin surface and the ambient dose equivalent rate Hp 10 under the skin.
If the doses measured are too high, the alarm is triggered, and the professional must take the necessary safety precautions and inform the dosimetry service and the Radiation Protection Advisor.
After use, the wearer can store it in a holder connected to the system for recharging, or connect it to a reader for transferring measurement data.
Dosimeters are not waterproof and must not be exposed to sunlight or high temperatures. They must be handled with care.
In the event of shock, have it checked by a company specializing in dosimetry.
Calibration is the process of verifying that a transducer measures accurately according to the manufacturer's datasheet .
Validate and check the value read. Please refer to the manufacturer's manual for further details. We advise you to call in a professional to carry out the calibration.
In general,calibration is recommendedat least once a year, or when there is a significant change in the use of an operational dosimeter (e.g. change of user).
If you use your dosimeter regularly and have had no problems with your measurements, then a bi-annual calibration may suffice.
Consult your dosimetry service.
You must choose a personal electronic dosimeter after carrying out an analysis to determine the nature and energy of the radiation in your environment, as well as the conditions of use and the radiation protection measures in place.
You must choose an instrument:
The most innovative models feature telemetry functions to monitor irradiation at a distance from the wearer.
Don't hesitate to ask for information and support from a professional for this analysis, and to help you make the right choice of operational dosimetry solutions and guarantee the safety of your department.
The price depends on the type of device you choose.
Most models cost between 600 and 1,200 euros.
Many factors influence the price of an operational dosimeter: its construction, its size and weight, its features, the presence of additional functions such as wifi or Bluetooth communication...
Choose a reliable supplier like Fuji Electric France, which offers excellent service.
That way, if something goes wrong with your device or you need spare parts after a while, they'll be able to help you quickly and easily.
