Toward Single-Pulse Monitoring for FLASH Radiotherapy

FLASH radiotherapy is an emerging technique that uses high dose rates (~40 Gy/s) and high dose-per-pulse values (~1 Gy/pulse) by delivering the total dose in a single session, resulting in significantly shorter treatment times and safeguarding healthy tissues. In this field, single-pulse dose measurements appear critical for understanding the tissue-radiation interaction when high-intensity pulses and high dose rates are involved. In this work, we describe a compact high-precision electronics coupled to a diamond dosimeter for pulse-by-pulse monitoring of electron packets emitted by medical LINACs. The front-end can be used with a full scale up to tens of nC. Therefore, in the case of detectors with a sensitivity around 1 nC/Gy, the system is able to acquire doses up to tens of Gy/pulse, as required in FLASH. The detection prototype was characterized in the lab, emulating charge-pulses up to 30 nC. An excellent linearity was observed in the wide range 40 fC - 30 nC with a readout error lower than ±0.5%. In addition, the diamond dosimeter irradiated by electron-packets generated by a medical LINAC was connected to the realized electronics for field-tests. Experimental results demonstrate that the proposed detection system is able to monitor the intensity of individual pulses, confirming the wide versatility of the proposed electronics also to meet the FLASH therapy requirements.