Ponente
Descripción
Proton therapy is an important radiotherapy that achieves very high dose conformity around the target, allowing a better protection of the organs at risk (decreasing radiation side effect). However, the dose delivered to a tumor is still conditioned by the dose that can be tolerated by the surrounding normal tissues. An emerging approach called FLASH therapy [2,3] delivers a therapeutic dose several orders of magnitude faster (≈ 100 Gy/s) than in current clinical cases (0.05Gy/s).
The physical properties of silicon carbide (SiC) make it an interesting material for radiation dosimetry. The wide SiC band-gap decreases the rate of thermally generated charge carriers, reducing the leakage current and the noise compared to silicon. It also makes SiC essentially insensitive to visible light and temperature variations. SiC has a higher displacement energy threshold and thus a higher radiation hardness than silicon, and has a higher thermal conductivity which makes it more resistant to thermal shocks.
At IMB-CNM we have designed and fabricated novel silicon carbide PiN diodes with the aim to respond to the technological challenges of new radiotherapy approaches such as proton therapy and FLASH therapy and have performed their validation in relevant beams. For example, in a first characterization with FLASH electron beams, these diodes have shown their suitability for relative dosimetry up to a dose per pulse of 11 Gy [4].
In this contribution we will present the tests carried out with these detectors at the CNA in Sevilla, with the aim of studying their signal response, sensitivity and radiation hardness with 14MeV proton beams up to a cumulative dose of 1.5 kGy. The diodes were operated without external bias voltage and an ionization chamber was used for reference dosimetry. The diodes show a pre-irradiation sensitivity of 3.2 ± 0.4 nC/Gy. The diode response is stable up to 1.5 kGy with a ±4% deviation that can be attributed to beam drift during the irradiation. The diode dark current was not affected by the accumulated dose. These results make SiC diodes a very promising option for dosimetry in proton beams.
[1] Schardt, D. et al.,Reviews of Modern Physics, 82(1), 383–425
[2] Favaudon V. et al., Science Translational Medicine, Vol. 6, Issue 245, pp. 245Ra93, 2014
[3] Zhang Q. et al., Radiation Research, 194(6), 656-664, (27 August 2020).
[4] Fleta C. et al., Physics in Medicine and Biology, submitted
