Ever wondered how professionals measure an individual’s exposure to ionizing radiation? What are the types of dosimeters?
The answer: Active and Passive dosimetry. Intrigued?Radiation dosimeters are devices specifically designed to measure and monitor exposure to ionizing radiation, playing a crucial role in occupational safety.
Active dosimeters offer real-time radiation exposure data, while passive dosimeters record radiation over time, analyzed later.Personal radiation detectors are used by radiation workers to ensure safety and compliance with regulatory standards.
Dive in to uncover the intricacies and applications of both active and passive dosimetry, and why they’re pivotal in the realm of radiation safety. Ready to embark on this enlightening journey?
This guide takes you through all the steps necessary to understand what are the two types of personal dosimetry and what is the difference between active and passive dosimetry.
What are the two types of personal dosimetry ?
Personal dosimetry, used to measure an individual's exposure to ionizing radiation, is categorized into two main types:
1. Active dosimetry : Provides real-time radiation exposure data.
2. Passive dosimetry: Records radiation exposure over a period, which is then read later.
Both types help ensure safety standards are maintained in environments with radiation exposure.
Both types help ensure safety standards are maintained in environments with radiation exposure. Dosimetry measures radiation to ensure that exposure limits are not exceeded.The operational quantity is a key concept in dosimetry, used to assess radiation exposure for regulatory purposes. The personal dose equivalent is an operational quantity used to estimate the dose received by a radiation worker at a specific point on the body.A radiation worker is anyone who works in environments where exposure to ionizing radiation is possible, such as those operating radiation-emitting devices or handling radioactive materials.
Operational dosimetry, also known as active dosimetry, uses an active dosimeter—a device that provides real-time dose measurement—to monitor exposure as it occurs.
Active dosimeters are essential for monitoring radiation levels and ensuring that occupational dose limits are not exceeded. They are used to monitor the dose received by workers in nuclear power plants handling radioactive materials, and in nuclear medicine for the health, industry, defense and security sectors.
In particular, it can be used to pinpoint where overexposure is occurring, so that action can be taken quickly.
This is provided by an electronic device called a personal electronic dosimeter, which can be used both to measure the dose received by the whole body and to monitor a radioactive zone.
These devices can detect photons and measure dose rate, providing immediate feedback on radiation exposure. These devices are worn on the body, at chest level, and record dose information from ionizing radiation sources(X-rays, Gamma rays, Beta rays, Neutrons).
Active dosimeters can provide an immediate reading of exposure levels on site, while passive or delayed-reading dosimetry devices measure a cumulative dose over the period of use.
Passive dosimeters record the accumulated dose over the wear period, which is important for assessing long-term exposure and ensuring compliance with dose limit regulations. When the wear period ends, the dosimeter is returned for analysis and dose records are updated.
Whole body dosimeters and whole body badges are used to measure the total dose received by the entire body, supporting regulatory compliance and safety management.Passive dosimeters do not provide immediate readings like operational dosimeters do!The individual operational dosimeter provides the wearer with an immediate indication of the ambient dose equivalent rate Hp(10).
It features adjustable visual and audible alarms and data logging functions.
There can be a significant difference between the different types of dosimeters measurements due to the measurement uncertainty inherent in the technology of each instrument.
Sensor compatibility can also affect measurement (magnetic field, drop or shock, temperature).
It's important to choose the right sensor for the conditions in your industry,including body dosimeters for whole-body exposure and other dosimeters such as extremity or area monitors, in order to obtain reliable and accurate measurement results. The presence of beta emitters can also influence the choice of dosimeter, as some types are better suited for detecting specific radiation sources.
To find out more about how to deal with these deviations, please consult the NF ISO 15690:2013 standard, available fromAFNOR.
External dosimetry, which measures external exposure outside the body, is a tool for assessing the dose received by a person in a supervised or controlled area. Accurate measurement of doses is essential for effective monitoring and regulatory compliance.
The main aim of this process is to identify workers who have been exposed to certain working conditions. The level of this exposure is also a key piece of information to be determined.
Once this type of data has been collected, workers can take appropriate action. This enables them to reduce their exposure and avoid overexposure.
It is important to note that these actions must comply with regulatory requirements. In France, these rules are defined by Article R4451-64 of the Labor Code. The Health Physics Society is also a recognized source of authoritative information on radiation safety and occupational dose management.
According to French regulations and decree no. 18-437 of June 4, 2018 amended by decree no. 2021-1091 of August 18, 2021 relating to worker protection against the risks associated with ionizing radiation, the employer ensures appropriate individual dosimetric monitoring management to monitor compliance with regulatory thresholds.
The Radiation Protection Advisor (RPA ) (formerly known as the Radiation Protection Competent Person (RCP)), under the responsibility of the plant manager, is responsible for ensuring that dosimetry is implemented in the plant.
The employer may also hire a radiation protection officer (RPO).
Health and safety regulations require classified employees entering a supervised area to use at least one operational dosimeter. Results and data must be transmitted weekly to SISERI (Système d'Information de la Surveillance de l'Exposition aux Rayonnements).
In addition, active or operational dosimetry is mandatory for access to controlled areas for professionals with a higher risk of exposure.
The active dosimeters are advanced electronic devices designed to measure exposure to ionizing radiation in real time. Unlike passive dosimeters, which require analysis after the fact, active dosimeters continuously display dose rate and cumulative dose, providing immediate feedback to users. This capability makes them essential in environments where reactivity and instant dose monitoring are paramount.
Active dosimeters are particularly used in high-risk environments such as nuclear power plants, medical radiology departments, nuclear medicine and radiological emergency response. They are also widely used inindustrial imaging, research laboratories and defense applications, where radiation levels can vary rapidly.
These devices generally detect gamma and X-rays, and some models also measure beta radiation. They often incorporate audible and visual alarms that are triggered as soon as a predefined dose threshold is reached, enabling immediate action. The most common models include individual electronic dosimeters (EPD) and direct ion storage dosimeters (DIS), capable of providing both instantaneous rate and cumulative dose.
One of the major advantages of the active dosimeter is its ability to improve radiation protection in real time. By signalling any rise in radiation levels, it enables operators to act quickly: evacuate, take shelter, or adjust procedures. This responsiveness also helps optimize workflows, particularly in medical and industrial environments, while respecting the ALARA (As Low As Reasonably Achievable) principle.
Other benefits of active dosimeters include data logging, wireless connectivity for centralized monitoring, and integration with radiation protection management software. These features are ideal for continuous monitoring at complex sites, facilitating the work of radiation protection managers.
Although they are more expensive and require regular maintenance (calibration, battery), their accuracy, responsiveness and communication capabilities make active dosimeters an indispensable tool in modern radiological monitoring programs.
Passive dosimeters are essential devices for measuring exposure to ionizing radiation in professional environments. Unlike active dosimeters, they require no external power source, making them a reliable, stand-alone solution for individual dosimetry.
These devices detect various types of radiation - gamma, X-ray, beta - and are widely used in healthcare facilities, nuclear installations and industrial sites. Among the most widely used types are thermoluminescent dosimeters (TLD) and optically stimulated luminescence (OSL).
Passive dosimeters record the cumulative dose received over a defined period (generally from several weeks to several months). This record is essential to ensure radiological safety, monitor personnel exposure, and guarantee compliance with regulatory limits.
Simple design, no heavy maintenance, affordable cost, compact and lightweight format: these are just some of the advantages that make passive dosimeters suitable for large-scale deployment, particularly in sectors requiring long-term monitoring. They also offer permanent, verifiable traceability, crucial for regulatory audits and long-term medical monitoring.
In short, passive dosimeters are a trusted solution for protecting workers exposed to radiation and maintaining a high level of safety in sensitive environments.
Although dosimeters are indispensable instruments for radiation monitoring, they do have certain limitations that it's important to be aware of in order to make the right choice for the job in hand.
These constraints underline the importance of choosing the right dosimeter for each working environment and regulatory requirement.
Dosimeters are used in a wide variety of sectors to monitor and manage exposure to ionizing radiation.
In the medical field, they are essential for monitoring the radiation dose received by nursing staff, patients and visitors, ensuring that exposure remains within set safety limits. Passive dosimeters (TLD, OSL) are often used for regular monitoring, while active dosimeters (EPD) are preferred in interventional radiology or nuclear medicine, where real-time display is essential.
Nuclear power plants rely on dosimeters to monitor workers' occupational exposure and ensure compliance with strict regulatory limits. Active dosimeters are widely deployed on site to provide an immediate warning if thresholds are exceeded, supplemented by passive dosimeters for regulatory archiving.
In the aerospace sector, dosimeters are used to study the effects of ionizing radiation on the human body, particularly for astronauts exposed to cosmic radiation. Highly sensitive passive dosimeters are used for long missions, while active devices are used for in-flight monitoring.
Civil protection and emergency response teams also use dosimeters to detect and respond rapidly to radiological threats, particularly during incidents involving radioactive materials. In these situations, active dosimeters are preferred for their ability to provide immediate alerts and real-time measurements in the field.
Beyond these fields, dosimeters are also used in research, education, environmental monitoring and remediation projects. Passive dosimeters are preferred for their reliability, low cost and ability to measure cumulative exposure over long periods.
Their ability to measure and record radiation dose makes them an indispensable component of radiation protection programs, ensuring the safety of people and the preservation of the environment from the harmful effects of ionizing radiation.
To guarantee regulatory compliance and the safety of your teams, turn directly to a dosimeter manufacturer offering a complete solution: equipment (individual dosimeters, reading terminals, etc.), integrated telemetry services and personalized support. When you choose a manufacturer with its own technologies, you can be sure of reliable measurements, traceable data and implementation tailored to your operational constraints.
Before investing in a dosimetry solution, there are a number of essential criteria to consider in order to guarantee the reliability, compliance and longevity of your radiation protection system:
REPUTATION
QUALITY
DELIVERY DEADLINES
Operational dosimetry is an invaluable tool for providing real-time information and limiting workers' exposure to ionizing radiation.
It's important to comply with legislation when installing a system, and to make sure you buy a solution from a recognized manufacturer to guarantee your safety and proper risk management.
