Metrology

France’s national metrology lab for ionizing radiation, LNHB (Laboratoire national Henri-Becquerel), is an active participant in the Doseo research center for radiotherapy technology at CEA LIST. LNHB conducts research, establishes and maintains reference measurements, and boasts cutting-edge measurement capabilities.

LNHB operates under the aegis of France’s national measurement and testing lab (LNE). Like any national metrology lab, LNHB has been tasked with implementing in a given field the International System of Units, SI, and giving users access to the metrological references they need within a strict framework of total traceability.

LNHB’s activities focus on:

• R&D to develop new metrology standards and radiation detection systems
• Maintaining the existing references as effectively as possible and benchmarking them against international references
• Contributing to better quality and consistency of measurements at the national level
• Training and transferring knowledge to users

The scope of LNHB’s activities covers radioactivity measurement (the Becquerel and its derivatives); neutron beam emission rate measurement (n.s-1); and dosimetry of photons and charged particles (Gray and Sievert).

R&D in dose metrology for radiotherapy

Main R&D areas for radiotherapy at LHNB:

• Improve national dosimetric references, stated as air kerma and absorbed dose to water, for external radiotherapy and brachytherapy by updating and adding absolute measurement instruments (new ionization chambers, new water and graphite calorimeters)
• Develop innovative radiation detection systems and dosimetric references for new external radiotherapy techniques (intensity-modulated radiation therapy, stereotactic body radiotherapy); LNHB is an active participant in European Metrology Research Programme (EMRP) projects (JRP7-EBCT, HLT09-MetrExtRT) under the aegis of EURAMET
• Develop methods for transferring dosimetric references to users in medicine and industry
• Develop and characterise 3D dosimetric methods, using chemical gels, especially for dosimetric quality controls required for external radiotherapy and brachytherapy treatments

Metrological reference sources

LNHB has reference radiation sources at Doseo: a ⁶⁰Co source and linear medical-grade accelerator for external radiotherapy;  ¹⁹²Ir, ⁶⁰Co and ¹²⁵I sources for brachytherapy; a ⁶⁰Co closed irradiator for high-dose irradiation in industrial settings and for sterilizing medical systems.

Metrological measurement and calculation capabilities

LNHB develops and uses a variety of primary dosimetric measurement techniques, such as calorimetry and ionometry, as well as secondary measurement techniques like chemical dosimetry, electron spin resonance (ESR), and thermoluminescence.

We also use Monte Carlo codes for the interactions between radiation and matter—Penelope, EGS, and MCNPX—to calculate beam energy spectra and accurately determine the correction factors.