Background and Aims

A diamond-based detector is being developed to solve the limitation of online monitoring in Microbeam Radiation Therapy (MRT), a synchrotron-based technique using a micro-beam matrix of low energy photons (100 keV range) at very high dose rates (kGy/s range). Stripped diamond detectors are used for portal monitoring.

Methods

Bulk diamond-based detectors (4.5x4.5 mm² area) have been tested under a single 50x800 µm² MRT micro-beam to test the linearity of the diamond detector response for dose rates ranging between 1 and 12000 Gy/s at European Synchrotron Radiation Facility. Recently, a first stripped diamond detector (eight 238 µm-wide strips) prototype was tested under synchrotron micro-beam array. The variation between each strip in terms of detection efficiency has been investigated together with the charge collection distribution in the 60 µm inter-strip area.

Results

The bulk diamond detectors exhibit an almost perfect linear response with respect to the dose rate (the response of four diamond detectors is presented on next figure).

The first characterization of the stripped detector prototype has shown a signal variation lower than 2% between each strip. No charge collection loss is observed in the inter-strip area.

Conclusions

Linearity and reproducibility of the measured signals demonstrate the potential of diamond-based stripped detectors for MRT real-time portal beam monitoring. A multi-stripped diamond detector coupled with multi-channel charge integrator developed at LPSC is being tested to monitor simultaneously the micro-beam and inter-beam fluxes.

Acknowledgements: Work supported by the LabEx PRIME and the Idex Université Grenoble Alpes