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IEC 62387 — Passive Integrating Dosimetry Systems for Radiation Protection
Standardising measurement performance for TLD, OSL, and RPL passive dosimetry in personal and environmental monitoring
IEC 62387 is the international benchmark for passive integrating dosimetry systems used in radiation protection. It applies to dosemeters that measure external photon and beta radiation through solid-state detectors that accumulate dose information over time and are read out later. The standard covers technologies such as thermoluminescence dosimetry (TLD), optically stimulated luminescence (OSL), and radiophotoluminescence (RPL). It specifies performance requirements, type-test procedures, and environmental influence testing to ensure consistent, traceable dose measurements across all operational conditions.
Although IEC 62387 was originally published as a two-part standard (62387-1 and 62387-2), the current consolidated edition provides a unified framework for both personal and area passive dosimetry systems, covering the full energy range from 10 keV to 10 MeV photons and beta energies up to 10 MeV.
1. Detector Technologies and System Architecture
The standard classifies passive dosimetry systems by their physical readout mechanism. Each technology has distinct advantages for specific monitoring scenarios:
| Technology | Readout Method | Typical Dose Range | Key Advantage |
|---|---|---|---|
| Thermoluminescence (TLD) | Heating to 200–400°C releases trapped electrons | 10 μSv – 10 Sv | Wide dynamic range, reusability |
| Optically Stimulated Luminescence (OSL) | Green laser stimulation of Al2O3:C crystals | 10 μSv – 10 Sv | Fast readout, multiple re-reads possible |
| Radiophotoluminescence (RPL) | UV laser excitation of silver-activated phosphate glass | 10 μSv – 10 Sv | Non-destructive readout, permanent storage |
All systems must include a detector element, a reader instrument, evaluation software, and a calibration traceable to national primary standards. The standard mandates that the combined standard uncertainty of the whole system shall not exceed the values given in the relevant operational quantity requirements (Hp(10) for personal dose equivalent, H*(10) for ambient dose equivalent).
2. Performance Requirements and Type Testing
IEC 62387 defines a comprehensive set of performance tests that every passive dosimetry system must pass for type approval. The most critical tests address energy and angular response, linearity, reproducibility, and environmental robustness:
A key requirement is the «relative response» criterion: over the entire energy range (typically 10 keV to 10 MeV for photons), the measured dose value must remain within ±30% of the true value when referenced to 137Cs (662 keV) calibration. This is particularly challenging at low photon energies where photoelectric absorption in the detector housing can significantly alter response.
The type-test programme includes the following categories:
- Photon energy and angular response — Tests at 7–10 reference energies from ISO 4037-1 narrow-spectrum series, at angles 0°, 20°, 40°, 60°.
- Beta energy response — Using 90Sr/90Y, 204Tl, and 147Pm sources with defined residual ranges.
- Linearity — Dose values from 0.1 mSv to 10 Sv must show less than 10% deviation from linear.
- Reproducibility — Repeated measurements must yield a coefficient of variation better than 7.5% at 1 mSv.
- Fading — Loss of stored signal must not exceed 10% over a 30-day period at 30 °C.
- Environmental influences — Temperature (-10 °C to +40 °C), humidity (up to 95% RH), light exposure, and mechanical shock.
3. Engineering Design Insights for Passive Dosimetry Systems
Designing a compliant passive dosimetry system involves several engineering trade-offs that go beyond simply selecting a detector material. The following insights are critical for developing robust commercial dosimetry products:
Filter optimisation is the single most impactful design parameter. A multi-element filter pack (typically Cu, Al, and plastic) combined with a single detector element per badge allows energy discrimination through a «multi-element algorithm» that deconvolves the photon energy distribution. This enables accurate Hp(10) and Hp(0.07) estimation from a single readout cycle.
Detector encapsulation and housing: The housing must provide mechanical protection without introducing excessive energy dependence. Low-Z materials such as ABS plastic with thin aluminium inserts are preferred. Any metallic parts must be positioned outside the sensitive measurement volume to avoid fluorescence artefacts at low photon energies.
Fading compensation: For TLD systems, signal fading is temperature-dependent and follows first-order kinetics. The reader software must implement a fading correction algorithm based on the measured ambient temperature history or a conservative worst-case model. OSL systems generally exhibit less fading but require careful optical shielding from ambient light during storage and transport.
Reader calibration and QA: A built-in reference light source (e.g., a stable LED or 14C-activated phosphor) should be included in every reader to correct for PMT gain drift and optical component ageing. Weekly quality assurance checks using a reference dosemeter set are recommended to maintain the calibration within the required ±5% stability limit.
4. Applications and Compliance in the Field
Passive dosimetry systems certified under IEC 62387 are deployed across numerous radiation protection scenarios, each with specific operational demands:
| Application | Dosemeter Type | Critical Requirement |
|---|---|---|
| Personal monitoring of radiation workers | TLD/OSL badge, whole-body and extremity | Hp(10) ± 30% accuracy over 30 keV–3 MeV |
| Environmental area monitoring | RPL/TLD environmental pack | Long-term stability, < 10% fading over 3 months |
| Medical physics (patient dose audit) | OSL nanoDot | Accuracy better than 10% at diagnostic energies (20–150 keV) |
| Nuclear industry accident dosimetry | High-range TLD / RPL | Linear response up to 10 Sv without saturation |
A common pitfall in field deployment is the mismatch between the calibration phantom (ISO water slab phantom) and the actual wearing position on the body. For extremity dosemeters worn on fingers, the backscatter conditions differ significantly from the trunk, potentially introducing errors of 20–40% if not corrected by a dedicated finger phantom calibration.
5. Conclusion
IEC 62387 provides a rigorous and comprehensive framework that has become the global reference for passive integrating dosimetry. Its detailed type-test requirements ensure that TLD, OSL, and RPL systems deliver consistent, traceable dose assessments across the full range of operational conditions encountered in radiation protection. For engineers and manufacturers, mastering the interplay between detector material selection, filter design, reader optics, and correction algorithms is essential to achieving type approval and building trust in passive dosimetry services worldwide.
Q1: What is the difference between IEC 62387 and IEC 61066?
IEC 61066 specifically covers TLD systems for personal and environmental monitoring, while IEC 62387 broadens the scope to include OSL and RPL technologies under a single unified performance standard. IEC 62387 effectively supersedes IEC 61066 for newer systems.
IEC 61066 specifically covers TLD systems for personal and environmental monitoring, while IEC 62387 broadens the scope to include OSL and RPL technologies under a single unified performance standard. IEC 62387 effectively supersedes IEC 61066 for newer systems.
Q2: Can OSL dosemeters be re-read after the initial measurement?
Yes. One advantage of OSL over TLD is that the readout consumes only a small fraction of the trapped charge, enabling multiple re-reads with minimal signal depletion. This is valuable for retrospective dose verification.
Yes. One advantage of OSL over TLD is that the readout consumes only a small fraction of the trapped charge, enabling multiple re-reads with minimal signal depletion. This is valuable for retrospective dose verification.
Q3: How often must a passive dosimetry system be recalibrated?
The standard recommends recalibration at intervals not exceeding 12 months, with a full type-test repeated every 5 years or whenever significant hardware or software changes are introduced.
The standard recommends recalibration at intervals not exceeding 12 months, with a full type-test repeated every 5 years or whenever significant hardware or software changes are introduced.
Q4: What is the significance of Hp(10) in the context of this standard?
Hp(10) is the personal dose equivalent at a depth of 10 mm, which approximates the dose to internal organs. It is the primary operational quantity for photon and beta radiation monitoring in personal dosimetry per ICRU recommendations.
Hp(10) is the personal dose equivalent at a depth of 10 mm, which approximates the dose to internal organs. It is the primary operational quantity for photon and beta radiation monitoring in personal dosimetry per ICRU recommendations.
