First Characterization of Novel Silicon Carbide Detectors with Ultra-High Dose Rate Electron Beams for FLASH Radiotherapy

Abstract

Ultra-high dose rate (UHDR) beams for FLASH radiotherapy present significant dosimetric challenges. Although novel approaches for decreasing or correcting ion recombination in ionization chambers are being proposed, applicability of ionimetric dosimetry to UHDR beams is still under investigation. Solid-state sensors have been recently investigated as a valuable alternative for real-time measurements, especially for relative dosimetry and beam monitoring. Among them, Silicon Carbide (SiC) represents a very promising candidate, compromising between the maturity of Silicon and the robustness of diamond. Its features allow for large area sensors and high electric fields, required to avoid ion recombination in UHDR beams. In this study, we present simulations and experimental measurements with the low energy UHDR electron beams accelerated with the ElectronFLASH machine developed by the SIT Sordina company (IT). The response of a newly developed 1 × 1 cm2 SiC sensor in charge as a function of the dose-per-pulse and its radiation hardness up to a total delivered dose of 90 kGy, was investigated during a dedicated experimental campaign, which is, to our knowledge, the first characterization ever done of SiC with UHDR-pulsed beams accelerated by a dedicated ElectronFLASH LINAC. Results are encouraging and show a linear response of the SiC detector up to 2 Gy/pulse and a variation in the charge per pulse measured for a cumulative delivered dose of 90 kGy, within ±0.75%.

Silicon carbide detectors for dosimetry and monitoring of ultra-high dose rate beams

“…A similar SiC detector is used for the present work and will be described in detail in the next section. The SiC device demonstrated a linear charge response up to 2 Gy/pulse, in contrast to a Silicon diode that saturated before reaching 0.5 Gy/pulse under similar conditions [14]. These findings suggest that these solid-state detectors hold potential as alternatives to ionization chambers or Silicon-based dosimeters for real time dosimetry.…”

“…and not able to provide an "on-line" information), and identifying new technologies that can overcome the limitations encountered with traditional active detectors. For instance, solid-state detectors, such as diamond [13] and Silicon Carbide (SiC [14]), have recently emerged as a promising solution. According to Marinelli et al (2022) [13], a novel diamond Schottky diode detector prototype (Flash diamond) developed for FLASH-RT showed a linear charge response up to a dose per pulse of 26 Gy/pulse when irradiated with the FLASH electron beam.…”

“…According to Marinelli et al (2022) [13], a novel diamond Schottky diode detector prototype (Flash diamond) developed for FLASH-RT showed a linear charge response up to a dose per pulse of 26 Gy/pulse when irradiated with the FLASH electron beam. Also, in a study by Romano et al (2023) [14], the performance of novel SiC detectors were investigated using UHDR electron beams. A similar SiC detector is used for the present work and will be described in detail in the next section.…”

“…SiC detectors are emerging as one of the promising alternatives for dosimetry and monitoring of UHDR beams. They exhibit high radiation hardness, fast response, high sensitivity, and dose rate independence [14,17]. Table 1 provides a comparison of some properties between Silicon (Si), -2 -…”

“…Figure 2b shows the SiC sensor of 10 μm active thickness and 1×1 cm 2 active area. In a previous work [14], the first dosimetric characterization of the novel SiC detector was performed with UHDR electron beams. -3 -…”