Evaluation of a thin microstrip detector for high spatial resolution dosimetry

VTT and Aalto University have supplied thin microstrip detector prototypes to CMRP for evaluation for the high spatial resolution dosimetry. The evaluation for dosimetry in microbeam radiation therapy (MRT) was done in a synchrotron microbeam at ESRF, France. Measurements studied a response of a single strip on the synchrotron microbeam in face-on and edge-on modes using CMRP designed and developed readout electronics for a parallel readout of single strips. Measurements were done in a passive mode without bias voltage and the detector was scanned through an array of intensive planar microbeams with the nominal width of 50 µm. The face-on mode results to a full width at half maximum (FWHM) of 112 µm and a peak to valley dose ratio (PVDR) of 12. Charge sharing between the microstrips was observed to be essential due to the high intensity of the microbeams. In the edge-on mode, the measured FWHM was observed 100 µm and the PVDR to 500. Based on the results presented in this paper, the thin microstrip detector is a promising dosimeter for the high spatial resolution dosimetry in synchrotron MRT.