IEC 62387:2020 explained
The standard for integrating passive dosimetry systems used in individual, workplace and environmental monitoring.
- Designation
- IEC 62387:2020
- Title
- Radiation protection instrumentation — Dosimetry systems with integrating passive detectors for individual, workplace and environmental monitoring of photon and beta radiation
- Instruments
- Passive dosimetry systems — thermoluminescence, optically stimulated luminescence and film
- Committee
- IEC TC 45 / SC 45B, WG 8
- On this site
- Described here for reference. An evaluation tool for it is planned, not built.
Scope and purpose
The standard applies to dosimetry systems with integrating passive detectors measuring external photon and beta radiation in the dose range 0,01 mSv to 10 Sv. It covers personal dose equivalents Hp(10), Hp(3) and Hp(0,07), and the ambient and directional quantities H*(10), H′(3) and H′(0,07) — that is, individual, workplace and environmental monitoring in one document. The second edition was published in 2020.
A passive detector accumulates a signal during the monitoring period and produces no indication while it is doing so. The signal is recovered afterwards on separate equipment. Thermoluminescence dosemeters, optically stimulated luminescence dosemeters, radiophotoluminescent glass and film badges all work this way.
The unit of evaluation
The distinguishing feature of this standard is what is under test. For a survey meter or an active personal dosemeter the instrument is a single object that indicates a value. Here the indicated value is produced by a system: the detector, its holder, the reader, the evaluation algorithm, and the procedures that link them.
That system is the unit of evaluation, and it is the reason performance cannot be inferred from the detector material alone. Two laboratories using identical detectors and identical readers can produce different results, because the calibration, the correction for the individual detector’s sensitivity, and the algorithm that combines multiple detector elements into a reported dose all belong to the system rather than to the detector.
Characteristics distinctive to passive systems
Batch homogeneity
Detectors are used in large numbers and are not individually identical. The variation in response across a batch is a property of the system, and where individual sensitivity factors are applied the correctness of those factors becomes part of what is being evaluated.
Fading
Fading is the loss of stored signal between irradiation and readout. It depends on the detector material, on temperature, and on elapsed time. A monitoring period of three months and a monitoring period of one month are therefore not equivalent conditions, and a dose delivered at the start of a period is not read out identically to the same dose delivered at the end of it.
Fading has no counterpart in active instruments, and it is the characteristic most frequently underestimated when a passive system is specified.
Reusability and residual signal
Where detectors are re-used, the annealing process must return them to a defined state. Signal remaining from a previous period adds to the next result, and a system that does not remove it accumulates error across cycles.
Non-radiation influences
Light exposure, humidity and mechanical shock affect the stored signal in ways that depend on the detector type. These are influence quantities for a passive system in the same sense that temperature is for an ionization chamber.
Measured quantities
Personal dose equivalent Hp(d) is the dose equivalent in soft tissue at depth d below a specified point on the body, and as with active personal dosemeters the quantity is defined in the body. Irradiation for testing is performed on a phantom, and the depth selects the assessment: 10 mm for effective dose, 0,07 mm for skin, 3 mm for the lens of the eye.
The same standard also covers the ambient and directional quantities, which are defined in the ICRU sphere and are properties of the field. A passive dosemeter used as an area or environmental monitor indicates those instead, and is irradiated free in air rather than on a phantom. The same detector technology serves both purposes under different irradiation conditions, and confusing them produces a plausible value for the wrong quantity.
Related standards
| Standard | Relationship |
|---|---|
| IEC 61526 | Active personal dosemeters for the same personal quantities. Commonly worn together, with the passive dosemeter providing the dose of record and the active one providing the alarm. |
| IEC 60846-1 | Survey instruments for the ambient quantities, where the indication is available in real time. |
| ISO 4037 series | The reference photon fields and the phantom irradiation conditions. |
Coverage on this site
No evaluation tool for IEC 62387 exists here yet, and of the standards described on this site it is the least similar to the implemented one. The engine computes response and relative response from readings taken at a point in time; a passive system requires elapsed time between irradiation and readout as a first-class condition, and requires the batch rather than the single instrument as the population under test. That is a data model change, not a new calculation, but it is a substantial one.
This page cites clause numbers and describes methods in its own words. It does not reproduce the text or the tables of IEC 62387:2020, and it does not substitute for holding the standard. Obtain it from the IEC or an authorised national distributor.