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Dose metrology

List institute can count within its expert laboratories the Henry Becquerel National Laboratory (LNHB), French national laboratory for ionising radiations research. This significant role has been officially assigned to LNHB by the French National Laboratory on Testing and Metrology (LNE – Laboratoire National de métrologie et d’Essais) in charge of French metrology steering and monitoring. LNHB is particularly in charge of dose metrology for photons and charged particles. The laboratory activities cover R&D for new measurement standards and radiation detection systems development, keeping existing references at the best international level, measures quality and coherence maintenance at a national level, training and transfer to users.

The laboratory works also directly with partners from the medical sector for dosimeters calibration on radiotherapy and X-ray diagnosis on patients’ dose control. DOSEO platform is fully equipped to this purpose on radiotherapy and imaging technologies. LNHB works closely with industrial partners on radioprotection too.

Among our academic partners

Metrology national institutes: PTB, NPL NIST ; Paul-Sabatier University (Toulouse, France), Clermont-Ferrand University; international office for radiations measurment (Bureau international des Poids et Mesures - BIPM).

Assets

  • Active member of metrology international system
  • national dosimetry photons and neutrons standard measurements guardian
  • R&D activity covering the whole development cycle from metrology upstream research to final users transfer (measurement services, trainings)
  • major actor on DOSEO platform for radiotherapy and imaging technologies, continuous adaptation to radiotherapy new technics.

Major technologies

Graphite calorimeter for mini-beams radiotherapy dose measurment

graphite

Description

Because of recent technological evolutions, radiotherapy radiation beams’ size has strongly decreased up to a few millimetres in some cases. Conventional dosimetric standards established within 10cm length beams can not be used anymore to ensure doses’ metrological traceability when delivered through very small sized beams. Considering this issue a new graphite calorimeter has been developed for dose absolute measurement in new radiotherapy treatments. In order to ensure the necessary precision this dosimeter can measure temperatures increases inferior to 1 mK (milliKelvin).

Applications

Mini-beams radiotherapy

Major projects

Publications

  • S. Dufreneix, J.-M. Bordy, F. Delaunay, J. Daures, J. Gouriou, M. Le Roy, A. Ostrowsky, B. Rapp, L. Sommier, “Towards the establishment of dosimetric references in small fields using the new concept of dose-area product”, prés. à AAPM 56th Annual Meeting, Austin, USA, 20-24 juillet 2014.

Stereotaxic radiotherapy devices’ calibration by EPR/alanine dosimeter

Description

Intracranial stereotaxy devices are used for small brain tumours’ treatment. Among them, the GammaKnife uses 192 beams precisely collimated with cobalt-60 photons irradiating simultaneously the tumour. This method makes it possible to increase the delivered dose to the tumour sparing in the meantime the healthy tissues around. No primary reference being available for the moment for this kind of device, a measurement method has been set up using dosimeters made of small alanine beads and analysed by EPR (Electron Paramagnetic Resonance). It has been successfully tested in a clinical centre with disparities below 1% compared to the device values of reference.

Applications

Innovative radiotherapy devices whose radiation parameters are way too distant from conditions of reference.

Publications

X-ray beams spectral characterization

Intrabeam CdTe

Description

In the field of photon radiations below 300 keV for primary dosimetry activities it is crucial to have a good knowledge of photons spectrum’s emission. We have developed a characterization technic for beams of reference based on semi-conductors detectors that we put directly into the beam itself. This technic needs first a good detector characterization in order to control measurement disturbances and then a great expertise in spectrum exploitation interpretation. Thus, the measured and corrected spectrum via our own algorithms give a more accurate estimation of the X-ray tubes effectively emitted spectrum in comparison with the measurement from existing deterministic or Monte-Carlo codes.

Applications

X-ray tubes industrial or medical devices’ dosimetric characterization