## 1 _Article_  
_First Characterization of Novel Silicon Carbide Detectors with Ultra-High Dose Rate Electron Beams for FLASH Radiotherapy_  
**[PERSON] 1,2**, [PERSON] 1,*, [PERSON] 3,4, [PERSON] 1,5**, [PERSON] 6**,  
**[PERSON] 6**, [PERSON] 7,7**,8**, [PERSON] 6, [PERSON] 1,5**, [PERSON] 9,10**,  
**[PERSON] 6**, [PERSON] 11,12**,**, [PERSON] 8,13**, [PERSON] 7,8, [PERSON] 9,10**  
**and [PERSON] 14,15**  
can also cause side effects and toxicities to the healthy tissues or vital organs surrounding the tumour, which often limits the total dose that can be delivered to the tumour without provoking significative damage to the same tissues and, consequently, the curative efficacy of radiation. Therefore, new radiotherapy approaches are currently under development, especially to address the need to treat radioresistant tumours [1]. In this framework, radiotherapy employing ultra-high dose rate (UHDR) beams has recently been found to significatively reduce the collateral effect to the surrounding healthy tissues while maintaining the same required tumour control and damage efficiency, thanks to the so-called FLASH effect [2; 3; 4]. The FLASH effect was initially experimentally observed during several in vivo experiments in different types of tissue using low-energy electron beams accelerated by modified clinical LINAC accelerators. These studies have shown a nonnegligible reduction of normal tissue complication probability (NTCP) after irradiation with beams at dose rate >40 Gy/s while preserving the same tumour control probability (TCP) of conventional low-dose rate radiotherapy (RT), leading to a sensible enhancement of the therapeutic window in radiotherapy [5]. Experiments have also been performed with photon radiation [6] and proton beams accelerated with radio frequency (RF) machines [7; 8]. The FLASH radiotherapy (FLASH-RT) is indeed a promising technique currently being studied and consisting of delivering the prescribed radiation dose in a reduced total irradiation time of less than 200 ms using only a few pulses at an ultra-high dose rate. Nowadays, such sparing effect in normal tissues is not totally understood from both the experimental and theoretical point of views. Many hypotheses on the possible causes and origins of the FLASH effect are currently formulated worldwide and are based on radiophysics, radiobiology and radiochemistry concepts mainly connected to the different oxygen species abundance in normal and tumoral tissues. Considering the higher dose rate compared to conventional-RT, accurate dosimetry and beam monitoring for these modalities become challenging and require new approaches for the dose measurement before the transition of FLASH-RT to clinical practice [9; 10]. The employment of UHDR beams implies the revision of the dosimetric protocol and recommendations currently used as standards for the beam monitoring and dosimetry in conventional-RT and particle therapy [9]. Indeed, the response of the recommended active dosimeters used in the daily clinical practice during conventional-RT treatment can be strongly affected by the high instantaneous dose rate and dose per pulse that are needed to trigger the FLASH effect [11]. In this regard, ionization chambers are the standard reference dosimeters according to the international protocols for clinical dosimetry [12]. Their response under UHDR beams has been widely investigated showing a relevant ion recombination effect in the gas at these extreme conditions [13]. The amount of ion recombination occurring at UHDR regimes would require a big correction for the charge collection efficiency that leads to large uncertainties in the final absorbed dose measurements. At this purpose, new strategies are currently under study to accurately calculate the correction factors and to decrease the ion recombination as much as possible [14; 15; 16; 17].