IEC 61526:2024 explained
The standard for electronic personal dosimeters. Its fourth edition, published in 2024, changed both the instrument term and the title.
- Designation
- IEC 61526:2024
- Title
- Radiation protection instrumentation — Measurement of personal dose equivalents for X, gamma, neutron and beta radiations — Active personal dosemeters
- Instruments
- Electronic personal dosimeters worn on the body
- 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 active personal dosemeters — body-worn instruments with a digital indication that measure personal dose equivalent, and in most cases the personal dose equivalent rate, from X, gamma, neutron and beta radiation. In common usage these are electronic personal dosimeters, frequently abbreviated EPD.
“Active” distinguishes them from passive dosimetry systems, which accumulate a signal that is read out later on separate equipment. Those are covered by IEC 62387 and are a different instrument class with different requirements. An active dosemeter indicates dose while it is being worn, which is what makes an alarm possible and what makes rate-dependent behaviour a requirement rather than an incidental property.
Edition history
The fourth edition was published in 2024, and two things changed with it that affect how the standard is cited. It has since been amended once.
Change of designation for the instrument
Earlier editions used direct reading personal dose equivalent meters. The current edition uses active personal dosemeters. Both denote the same instrument class. A specification written against the older term is not thereby out of date, but a search on the old term will not find the current standard.
Change of title
The title changed correspondingly, and the operational quantities are no longer enumerated in it. Earlier editions named Hp(10) and Hp(0,07) in the title itself; the current title refers to personal dose equivalents without listing them.
Amendment 1 to the fourth edition
Amendment 1 was published in 2026. An amendment is not a new edition: the base document is still the fourth edition of 2024, and the amendment replaces parts of its text. Where the amended text is meant, the two are cited together as IEC 61526:2024+AMD1:2026, and the single document that carries the merged text is issued separately with the suffix CSV for consolidated version. A specification citing IEC 61526:2024 alone therefore names a document that is current, but not the latest text of it.
Measured quantities
The personal dose equivalent, written Hp(d), is the dose equivalent in soft tissue at depth d below a specified point on the body. It is the operational quantity for individual monitoring, and the depth d selects what is being assessed:
- Hp(10) — 10 mm depth, for effective dose from strongly penetrating radiation. This is the quantity of record for whole-body occupational exposure.
- Hp(0,07) — 0,07 mm depth, for skin dose. It is the relevant quantity for beta radiation and low-energy photons.
- Hp(3) — 3 mm depth, for the lens of the eye, where a dosemeter is intended for that purpose.
Distinction from the ambient quantities
Personal dose equivalent is not ambient dose equivalent. H*(10), the quantity that IEC 60846-1 survey instruments indicate, is defined in the ICRU sphere and is a property of the field alone. Hp(10) is defined in the body of the person wearing the instrument, and therefore includes backscatter from that body.
The practical consequence governs the whole test programme: an active personal dosemeter is irradiated mounted on a phantom, not free in air. A slab phantom of the specified construction stands in for the torso, and the conventional true value of Hp(10) is established for the instrument in that configuration. Testing a personal dosemeter free in air produces a value for a quantity the instrument does not indicate.
Characteristics distinctive to this instrument class
Several characteristics are shared with survey instruments — linearity across the measuring range, photon energy response, statistical fluctuation of repeated readings. Others are specific to body-worn instruments, and they are where an evaluation of an EPD differs most from an evaluation of a survey meter.
Angular response about two axes
A survey meter is pointed at the source. A body-worn dosemeter is not, and its orientation relative to the field changes as the wearer moves. The angular response is therefore evaluated over a wider range of incidence angles, and about both the horizontal and the vertical axis of the phantom, rather than in a single plane.
Response in pulsed fields
Dose delivered in short, intense pulses is a documented failure mode for counting instruments, because the instrument cannot resolve individual events within a pulse and under-responds by an amount that depends on the pulse structure rather than on the total dose. Interventional radiology and pulsed accelerators produce fields of this kind. Dedicated standards address pulsed-field dosimetry — IEC 62743 for electronic counting dosemeters and IEC 63050 for dosemeters in pulsed fields — and an instrument intended for such workplaces should be assessed against them as well.
Alarm behaviour
An EPD alarms on dose and on dose rate. Both thresholds are subject to accuracy requirements, and the dose rate alarm has a response time requirement: an alarm that is correct but arrives after the wearer has left the field has not performed its function.
Related standards
| Standard | Relationship |
|---|---|
| IEC 62387 | Passive dosimetry systems for the same quantities. Frequently worn alongside an EPD, with the passive dosemeter providing the dose of record. |
| IEC 60846-1 | Survey instruments for the ambient quantities. Different quantity, different phantom condition, different angular requirements. |
| IEC 62743 · IEC 63050 | Pulsed fields of ionizing radiation, where the counting behaviour of an active dosemeter is the limiting factor. |
| ISO 4037 series | The reference photon fields and the phantom irradiation conditions used to establish the conventional true value. |
Coverage on this site
No evaluation tool for IEC 61526 exists here yet. The engine that computes response, relative response, coefficient of variation and combined standard uncertainty is standard-independent, and the characteristics common to both instrument classes reduce to the same arithmetic. What an EPD evaluation additionally requires is the phantom condition and the two-axis angular geometry in the data model. That is the work, and it is planned rather than done.
This page cites clause numbers and describes methods in its own words. It does not reproduce the text or the tables of IEC 61526:2024, and it does not substitute for holding the standard. Obtain it from the IEC or an authorised national distributor.