For the last four years, the LNE-LNHB/LMD has been developing methods and material to measure the X-ray spectra of its X-ray tubes used to perform primary standards and transfers in medical or industrial fields. Two different measuring devices have been built. They include the possibility to use three different semiconductor detectors (Si-PIN, GeHP, CdTe) equipped with tungsten collimators with small apertures. Two rotation and translation stages were included to these benches for an automatic and precise alignment of the couple detector/collimator on the beam axis. Correction methods were developed for each detector, to take into account all the detection artefacts taking place into the semi-conductor crystal. They were included in specific spectrum correction programs. Characterization of 28 LNE-LNHB/LMD reference beams was carried out. It allows testing and validating all the different algorithms of spectrum correction developed at the laboratory. These results were compared to the calculated spectra obtained with the XCOMP5r and SpekCalc V1.0 software.

Molecular radiotherapy consists in the injection of a therapeutic agent with known activity in order to deliver a high-dose radiation directly to the tumors while sparing healthy tissues. The Euramet/EMRP project MetroMRT "Metrology for Molecular Radiotherapy" was intended to bring together national metrology laboratories and nuclear medicine services in order to give them metrological support in the field of molecular radiotherapy. In particular, LNE-LNHB was involved in the project for the standardization of ⁹⁰Y-labelled resin microspheres (SIR-Spheres). This therapeutic agent produced by Sirtex (Sydney, Australia) for selective internal radiotherapy is dedicated to the treatment of unresectable hepatic tumors by radioembolization. The primary activity measurement of ⁹⁰Y microspheres was carried out after their complete dissolution in the Sirtex vial. Two types of measurements using the TDCR method were used, one based on liquid scintillation and the other on the Cherenkov effect. An original method for the dissolution was developed at LNE-LNHB to optimize the homogeneity of the radioactive solution dedicated to primary measurements. A comprehensive description of the dissolution protocol implemented is reported in this article. The calibration of the ionization chambers at LNE-LNHB for the reference transfer of ⁹⁰Y-microspheres to end-users is also addressed. The influence of the inhomogeneity of the vial geometry on the uncertainty associated with calibration factors in the case of pure β ^- emitters such as ⁹⁰Y is presented. The standardization of SIR-Spheres was also aimed at lowering the 10% relative uncertainty given by Sirtex on the ⁹⁰Y-microspheres activity (3 GBq).

In this work we present the results of the first part of a research project aimed at offering a complete response to dosimeter manufacturers and users of the nuclear industry demand for high energy (6 MeV–9MeV) photon radiation beams for radiation protection purposes. Classical facilities allowing for the production of high energy photonic radiation (proton accelerators, nuclear reactors) are very rare and need large investment for development and use. We thus propose a novel solution, consisting in the use of a medical linear accelerator, allowing for a significant decrease of all costs. Using Monte-Carlo simulations (MCNP5 and PENELOPE codes), we have built a specifically designed electron-photon conversion target allowing for obtaining a high energy photon beam (with an average energy weighted by fluence of 6.17 MeV) for radiation protection purposes. Due to the specific design of the target, this “realistic” radiation protection high energy photon beam presents a uniform distribution of air kerma at a distance of 1 m, over a (30 × 30) cm² area. Two graphite cavity ionization chambers for ionometric measurements have been built. For one of these chambers we have measured the charge collection volume allowing for its use as a primary standard. The second ionization chamber is a transfer standard, as such it has been calibrated in a 60Co source, and in the high energy photon beam for radiation protection. The measurements with these ionization chambers allowed for an evaluation of the air kerma rate in the high energy photon beam for radiation protection: the values cover a range between 80 mGy·h^-1 and 210 mGy·h^-1, compatible with radiation protection purposes. Finally, we have calculated using Monte-Carlo simulations conversion coefficients from air kerma to dose equivalents in the range between 10 keV and 22.4 MeV, in specific geometrical set-ups, and for the spectral distribution of the fluence in the beam produced by the linear accelerator of LNE-LNHB.