Dosimeter for radiation

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.

Definition of a dosimeter for radiation

Definition of a dosimeter for radiation

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.

What is the use of a dosimeter for radiation?

What is the use of a dosimeter for radiation?

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.

 Dosimeter for radiation allows you to :

  • determine dose rate, dose and exposure measurements.
  • monitor your body's reaction to radiation exposure.

How does a dosimeter for radiation work?

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.

How does a dosimeter for radiation work?

By applying a reverse bias to the silicon diode, a depletion layer with extremely weak electrons is created and used as a detector assembly.
Simplistically, the silicon detector acts as a solid-state ion chamber operating in a pulse mode.
By optimising the composite metal filter shielding and electrical thresholds (to minimise noise), the energy response can be flattened.
A dose equivalent response is obtained by counting the detector pulses.

X-rays are similar to gamma rays

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.

What does a dosimeter for radiation measure?

What does a dosimeter for radiation measure?

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

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.

Why choose an operational dosimeter?

Why choose an operational dosimeter?

Operational radiation detectors are the best way to measure radioactivity in real-time. They have several advantages over delayed-reading dosimetry or passive dosimetry, such as providing an instantaneous reading.

This makes dosimeters for radiation ideal for situations where workers need an immediate reading with frequent monitoring - for example, when working in high-risk areas with dangerous radiation levels or contamination levels or when spending long periods in contaminated areas (emergency response).

They have visual and audible alarms that are triggered if the wearer's selected acceptable levels are exceeded.

Who has to wear a dosimeter for radiation?

You must wear personal dosimeters if you regularly work in a controlled area where ionising radiation is present.

Who has to wear a dosimeter for radiation?

For example, if you are :

  • workers and professionals in the nuclear industry,
  • engineers working in construction or the oil industry,
  • health care professionals,
  • firefighters, the military and other security professions,
  • personnel using hazardous materials on site,
  • persons in an area where ionising radiation or radioactive particles are present.

Individual dosimetric monitoring

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 :

  • Dose rate,
  • The average dose accumulated over a given period,
  • The maximum dose accumulated during a working day.

Workers must take care to respect the ALARA principle in order to limit their exposure.

How to wear a dosimeter for radiation?

How to wear a dosimeter for radiation?

A 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.

How to use a dosimeter for radiation?

How to use a dosimeter for radiation?

Detectors of radiation are designed to be easy to use. They are nominative and individual. They are supplied ready to use. They must be suitable for the radiation present.

After switching on the dosimeter, the wearer must activate it at a reading station located at the entrance to the controlled areas. The person must check and set the alarm threshold in the menu and then put on the detector. The active dosimeter allows you to see the instantaneous measurement to better protect yourself.

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 measurement data transfer.

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.

How to calibrate a dosimeter for radiation?

How to calibrate a dosimeter for radiation?

Calibration is the process of verifying that a sensor measures accurately according to the manufacturer's specifications.

  1. A dose should be measured by placing a source suitable to your sensor at a certain distance (reference point calibration) so that the actual dose value is comparable with the national standard. Determine the value of the reference dose R0.
  2. Calculate R0 from the activity of the reference source, the distance from the reference source to the dosimeter reference point (calibration distance) and the irradiation time.
  3. For calibration, place the source at the calibration distance from the radiation source and read the measured dose (R1).
  4. Calculate the new calibration factor using the following formula:
    C1 = C0 x R0 /R1
    C0 being the original factor. Compare the reference dose (R0) and the dose reading (R1). If there is an unacceptable difference between R0 and R1 , change the calibration factor (C1).
  5. To change the calibration factor, connect the dosimeter to a computer system and use the configuration software in calibration mode and enter the new factor.

Validate and check the value read. Please refer to the manufacturer's manual for further details. We advise you to call in a professional for 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 not had any problems with your measurements, then a bi-annual calibration may suffice.
Consult your dosimetry service.

Which type of dosimeter for radiation should you choose?

Which type of dosimeter for radiation should you choose?

You must choose a personal electronic dosimeter after conducting 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:

  • with ease of use,
  • quick implementation,
  • lightweight and robust,
  • with good battery life,
  • recording capabilities for data collection and monitoring of personal exposure levels over time,
  • with visual and audible alarms to warn users of abnormal radiation levels.

The most innovative operational dosimeters have telemetry functions to follow the 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 ensure the safety of your department.  

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How much does a dosimeter for radiation cost?

How much does a dosimeter for radiation cost?

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 active radiation detector: its construction, its size and weight, its functionality, the presence of additional functions such as wifi or Bluetooth,etc.

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.

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