Personal dosimeters – often also referred to as radiation dosimeters or dose measuring devices – are a central tool in modern radiation protection. They are used to monitor the individual radiation exposure of people who may come into contact with ionising radiation in their work environment. Whether in hospitals, in industry or in emergency services for disaster control – wherever radiation can affect people, precise dose measurement is crucial for safety.
The purpose of this article is to show why personal dosimeters are indispensable in many professions, how they are used in practice, and which legal regulations govern the use of these devices.
A brief look at radiation protection shows: In Germany, the Radiation Protection Act (StrlSchG) and the Radiation Protection Ordinance (StrlSchV) regulate the safe handling of radiation sources. These regulations stipulate that persons who are exposed to potentially relevant radiation levels must regularly measure and document their personal radiation dose. Personal dosimeters are the mandatory measuring instrument for this – and at the same time an important early warning system to ensure compliance with limit values.
It is therefore clear: anyone working in a radiation-relevant environment wears a personal dosimeter not only out of duty but above all out of responsibility. In the following sections, you will learn how these devices work, in which areas they are used and how they contribute to the protection of health and safety.
→ What is a personal dosimeter?
A personal dosimeter is a portable radiation dosimeter that measures, documents and – in modern devices – displays in real time the individual radiation dose of a person. The aim is to ensure that the legally defined limits for radiation exposure are not exceeded.
Personal dosimeters are worn directly on the body, usually on clothing in the chest area, in order to record the radiation exposure as representatively as possible for the whole body. In some cases, additional finger or ring dosimeters are used if certain body parts are particularly exposed.
How a personal dosimeter works
Measurement is based on the interaction of ionising radiation (e.g. gamma, beta or X-rays) with a detector element. Depending on the design, the radiation is either recorded directly electronically or stored in a carrier material for later evaluation.
Measurement process in three steps:
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Detection: The detector element registers incoming radiation.
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Evaluation: Depending on the dosimeter, the dose calculation takes place immediately (electronically) or later in a laboratory (passive).
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Documentation: The measured radiation dose is stored, displayed and archived.
Difference between passive and electronic dosimeters
| Type | Operating principle | Advantages | Disadvantages | Typical applications |
|---|---|---|---|---|
| Passive dosimeter | Stores the radiation effect in the measuring material, evaluation in the laboratory | Low cost, no power supply required | No real-time warning, evaluation only afterwards | Long-term monitoring in medicine, research, industry |
| Electronic personal dosimeter | Direct measurement with an electronic detector, real-time display | Immediate warning if limits are exceeded, data export possible | Higher purchase cost, battery replacement required | Fire brigade, disaster control, work with high radiation density |
Practical example: Modern electronic dosimeters such as the portable dose rate meters from our range offer acoustic and visual warning signals as soon as predefined threshold values are exceeded.
Measurement quantities explained simply
When measuring radiation dose, two main quantities are used:
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Dose (H): The amount of radiation absorbed by the body over a given period of time. Unit: millisievert (mSv) or sievert (Sv)
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Dose rate (Ḣ): The radiation dose per unit of time. Unit: millisievert per hour (mSv/h)
Example values:
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Natural background radiation in Germany: approx. 0.0001 mSv/h
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Dose rate in controlled areas (e.g. nuclear power plant): can be significantly higher depending on the work situation
A personal dosimeter is not only a legally required measuring instrument, but also a central safety tool that, depending on the design, can give immediate warnings or document long-term dose values. The choice between a passive and an electronic model depends heavily on the area of application – and thus also on whether real-time protection or long-term documentation is the priority.
→ Legal basis and obligations
The use of personal dosimeters is clearly regulated in Germany. The legal requirements are mainly derived from the Radiation Protection Act (StrlSchG) and the Radiation Protection Ordinance (StrlSchV). Both aim to protect people and the environment from the dangers of ionising radiation.
Radiation Protection Act (StrlSchG)
The Radiation Protection Act provides the legal framework for handling radioactive materials and technical radiation sources.
Key points regarding personal dosimeters:
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Definition of dose limits for occupationally exposed persons (e.g. max. 20 mSv per year for category A personnel)
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Obligation to monitor individual radiation exposure
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Requirement that measuring devices must comply with recognised technical standards
Radiation Protection Ordinance (StrlSchV)
The Radiation Protection Ordinance specifies the obligations laid down in the Act. Relevant for personal dosimeters:
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Mandatory wearing for persons in supervised or controlled areas
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Type of measurement: For official dose determination, approved official personal dosimeters (mostly passive measuring systems) must be used
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Real-time monitoring: In addition, electronic personal dosimeters can be used to receive immediate warnings in case of high radiation
Who must wear a personal dosimeter?
This obligation applies in particular to:
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Medical staff working with X-ray, CT or nuclear medicine procedures
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Industrial workers in controlled radiation protection areas (e.g. non-destructive testing, nuclear technology)
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Emergency services in disaster control (fire brigade, police, THW) when there is a risk of radiation
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Research staff in laboratories with radioactive materials
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Construction workers carrying out radon measurements or working in radioactively contaminated areas
Practical link: In our range you will find portable personal dosimeters for various applications – from rugged fire brigade models to compact dosimeters for the medical field.
Evaluation and documentation obligations
According to the StrlSchV, each dose determination must be regularly evaluated:
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Official dosimeters: Sent to a state-recognised evaluation centre after a set period (usually monthly)
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Electronic dosimeters: Measurement values can be stored, read and archived on site
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Documentation obligation: Employers must archive the measurement results for a prescribed period (often 30 years) to provide long-term evidence
The Dosimeter Act clearly specifies who must wear a personal dosimeter and how the determined values must be documented. Compliance with these obligations is not only a legal requirement but also an essential measure to protect one's own health.
→ Use in medicine
In medical facilities, radiation protection is part of daily work. Personal dosimeters are a central element for continuously monitoring the individual radiation exposure of staff. They help to comply with statutory dose limits and to protect the health of employees in the long term.
Typical sources of radiation in medicine
| Area | Radiation source | Typical application |
|---|---|---|
| Diagnostics | X-rays | Conventional X-ray, fluoroscopy |
| Imaging | Computed tomography (CT) | 3D imaging of organs and tissue |
| Nuclear medicine | Radionuclides (e.g. technetium-99m) | Scintigraphy, PET examinations |
| Radiotherapy | High-energy photons or electrons | Treatment of tumours |
| Research laboratories | Radioactive isotopes | Biomedical and pharmaceutical research |
Even in the operating room, staff may be exposed to relevant radiation during image-guided procedures (e.g. cardiac catheterisation, endoprosthetics).
Special requirements for medical staff
Medical personal dosimeters must:
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Be compact and lightweight so that they do not cause discomfort during long shifts
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Have high sensitivity to detect even low radiation levels
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Offer easy readability for quick checks
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Be officially approved so they can be used for legally required dose monitoring
In addition, many institutions have staff wear two dosimeters at the same time:
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Official passive dosimeter (e.g. film or TLD dosimeter) for statutory dose determination
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Electronic real-time dosimeter for direct monitoring during work
Practical examples in the medical field
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Radiology: Radiology assistants and doctors wear dosimeters on the collar of their gown or on the chest to record the whole-body dose
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Operating room: In high-radiation procedures, electronic dosimeters are used that provide immediate alarms
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Nuclear medicine: Staff working with radioactive preparations also use finger or ring dosimeters
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Research laboratories: Scientists working with isotopes document every radiation exposure for long-term studies
Product link tip: For use in clinics and medical practices, particularly compact, officially approved devices from our radiation measurement technology category are ideal, as they can be worn discreetly on a gown.
In radiation protection in medicine, the personal dosimeter is not only a legal requirement but also a practical tool to ensure safety in everyday work – from diagnostics to radiotherapy to research.
→ Use in industry
Even outside the medical field, radiation protection in industry plays a crucial role. Personal dosimeters are legally required in many industrial sectors to monitor employees’ individual radiation exposure. This particularly applies to industries working with technical radiation sources or radioactive materials.
Non-destructive material testing (NDT)
In non-destructive material testing – especially in industrial radiography – components are inspected for defects using X-rays or gamma rays without causing damage.
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Risk: Short-term high radiation intensities in the workplace
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Radiation protection measure: Obligation to wear official personal dosimeters as well as additional electronic real-time dosimeters
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Examples of application areas: Pipeline construction, pressure vessel testing, weld inspections
For this purpose, you will find robust portable dose rate meters in our range that operate reliably even under harsh construction site conditions.
Nuclear power plants and fuel element storage
In nuclear facilities, radiation protection is particularly strictly regulated.
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Areas of application: Reactor building, turbine hall, fuel element storage
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Types of radiation: Mainly gamma and neutron radiation
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Dosimeter requirements: High measurement accuracy, robust design, storage of long measurement series
Employees here usually wear two dosimeters:
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Official passive personal dosimeter (monthly evaluation)
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Electronic personal dosimeter with acoustic/visual alarm for real-time monitoring
Research facilities
In industrial and governmental research facilities, radioactive materials are used in experiments or testing processes.
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Examples: Materials research, radiation physics, reactor laboratories
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Special feature: Frequently changing radiation sources and measurement ranges require flexibly adjustable dosimeters
Construction sites with radon risk
Radon is a naturally occurring radioactive noble gas that seeps from the ground in certain geological regions of Germany.
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Hazard: Long-term exposure can increase the risk of lung cancer
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Use of dosimeters: Particularly important in civil engineering, tunnel construction or during renovations in radon precautionary areas
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Radiation protection measure: Combination of radon measurement and personal dosimeter for construction workers
For construction and renovation projects in radon areas, we recommend compact personal dosimeters specially optimised for long-term measurements.
The use of personal dosimeters in industry is not only a legal obligation but also a crucial safety measure. Whether on a construction site, in a power plant or in material testing – only with continuous dose monitoring can limits be reliably observed.
→ Use in disaster control
In disaster control, personal dosimeters are an indispensable tool to protect emergency services such as the fire brigade, police and THW from dangerous radiation exposure. Especially during operations where radioactive materials are released or contamination is suspected, the radiation dose of the personnel involved must be continuously monitored.
Emergency services in radiation protection operations
| Organisation | Typical tasks in radiation operations | Examples of dosimeter use |
|---|---|---|
| Fire brigade | Firefighting in nuclear facilities, decontamination, securing accident sites | Real-time dosimeter with alarm function on the protective suit |
| Police | Cordon off contaminated areas, secure evidence, personal protection | Compact dosimeters for discreet dose monitoring |
| THW | Technical assistance, recovery, deployment in flood or earthquake areas with radiation risk | Robust, waterproof dosimeters for long-term use |
Suitable, particularly robust models can be found in our radiation measurement technology category – ideal for outdoor use by fire brigades, police and THW.
Typical operational scenarios
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Accidents involving radioactive materials (e.g. transport or storage accidents)
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Contaminated zones after industrial accidents or natural disasters
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Fire incidents in nuclear or radiation-related facilities
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Explosive or terrorist situations involving the risk of radioactive materials (“dirty bomb” scenario)
Equipment requirements in disaster control
To ensure personal dosimeters operate reliably in extreme situations, they must meet the following requirements:
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Robust design – shockproof, waterproof, dustproof (IP protection class)
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Fast start-up – ready to measure immediately after switching on
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Alarm function – acoustic, visual and, if necessary, vibration warning when limit values are exceeded
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High measuring range – suitable even for scenarios with very high radiation intensity
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Ease of use – operable even with gloves, easy-to-read display
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Data storage – secure measurement data for later evaluation and operational documentation
In radiation protection for fire brigades, police and THW, a reliable personal dosimeter is essential. It enables emergency personnel to keep an eye on their safety even in critical situations and to comply with operational limits in accordance with regulations.
→ Selecting the right personal dosimeter
The decision to purchase a personal dosimeter depends largely on the field of application – whether in a hospital, on construction sites, in disaster control or in research and industry. When buying, be sure to consider the following criteria:
Selection criteria at a glance
| Criterion | Meaning | Recommendation |
|---|---|---|
| Measuring range | Indicates in which dose or dose rate ranges the device measures reliably | For medical purposes, a small measuring range is sufficient. For industry or disaster control, a wider (higher) measuring range is advisable. |
| Accuracy | The more accurate the measurement, the more reliable the radiation protection | Particularly recommended for radiation protection obligations. |
| Design | Depending on the application, the device should be lightweight and portable, or robust and protected | Medicine: compact and lightweight. Disaster control/construction: robust and IP-protected. |
| Alarm function | Warns of critical dose or dose rate values (optically, acoustically or via vibration) | Mandatory in noisy or highly contaminated environments. |
| Display | Clear display of measurement results (e.g. illuminated display) | Important when used in difficult lighting conditions. |
Practical link:
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For classic dose measurements and the personal dose equivalent (Hp(10)), models from the dose measuring devices category are suitable.
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For situations where the dose rate (mSv/h) must also be monitored, you can find suitable solutions under dose rate meters.
A personal dosimeter is not just a measuring instrument – it is an essential safety tool in all areas where ionising radiation may occur. Whether in medicine, industry or disaster control: continuous monitoring ensures compliance with limits and protection of health.
Summary: Safety through continuous monitoring
Personal dosimeters are indispensable companions wherever ionising radiation can occur. They provide reliable data, enable timely warnings and ensure compliance with legal dose limits. This makes them a central element of modern radiation protection.
Product tip: In our radiation measurement technology category you will find a wide selection of personal dosimeters for all areas of application.