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Dosimetry for the electronic brachytherapy (eBT) – EMPIR project: PRISM-eBT


Within the framework of the European Metrology Programme for Innovation and Research (EMPIR), six European National Metrology Institutes (NMIs) together with four additional partners from universities and clinics are collaborating in a joint research project to establish a harmonized, simplified and traceable dosimetry for electronic brachytherapy (eBT) in terms of absorbed dose to water.

The project consists of four work packages:

The aim of work package 1 is to establish primary standards for the absorbed dose rate to water for eBT devices at 1 cm depth of water and to establish transfer instruments and corresponding measurement procedures for the dissemination of this quantity to clinical practice.

In work package 2 a dosimetric methodology for skin eBT is being established traceable to a primary standard developed in work package 1.

In work package 3 detectors and measurement instruments suitable for the determination of 3D dose distributions in water by eBT devices are characterized to develop a standardized traceable calibration process.

With these detectors, dose distributions around such sources will be determined in work package 4. Special attention will be paid to the development of traceable, dosimetric methods for the determination of 3D dose distributions in water in order to make them available to medical physicists in the clinic.

Although the project is not yet complete, a catalog of eBT and eBT‑equivalent X‑ray photon fluence spectra measured or generated during the project has already been compiled. The catalog is available on the project website and provides a basis for spectrometry and dosimetry of eBT sources. Using a plastic scintillator detector, the dose profile and depth‑dose curve for an eBT source were determined with an accuracy of better than 2.5 %.


This research was accomplished within the framework of project 18NRM02 PRISM‑eBT that has received funding from the EMPIR programme co‑financed by the Participating States and from the European Union’s Horizon 2020 research and innovation programme.


Thorsten Schneider, Department 6.3, Working group 6.34

Rolf Behrens, Department 6.3, Working group 6.34