Microdosimetry in low energy proton beam at therapeutic-equivalent fluence rate with silicon 3D-cylindrical microdetectors.

Autor:	Guardiola C; Université Paris-Saclay, CNRS/IN2P3, IJCLab, F-91405 Orsay, France.; Université de Paris, IJCLab, F-91405 Orsay France., Bachiller-Perea D; Université Paris-Saclay, CNRS/IN2P3, IJCLab, F-91405 Orsay, France.; Université de Paris, IJCLab, F-91405 Orsay France., Prieto-Pena J; Departamento de Física de Partículas, Universidad de Santiago de Compostela, E-15782, Spain., Jiménez-Ramos MC; Centro Nacional de Aceleradores, E-41092 Sevilla, Spain., García López J; Centro Nacional de Aceleradores, E-41092 Sevilla, Spain.; Departamento de Física Atómica, Molecular y Nuclear, University of Sevilla, E-41080, Sevilla, Spain., Esnault C; Université Paris-Saclay, CNRS/IN2P3, IJCLab, F-91405 Orsay, France.; Université de Paris, IJCLab, F-91405 Orsay France., Fleta C; Centro Nacional de Microelectrónica (IMB-CNM, CSIC), Bellaterra, E-08193, Spain., Quirion D; Centro Nacional de Microelectrónica (IMB-CNM, CSIC), Bellaterra, E-08193, Spain., Gómez F; Departamento de Física de Partículas, Universidad de Santiago de Compostela, E-15782, Spain.
Jazyk:	angličtina
Zdroj:	Physics in medicine and biology [Phys Med Biol] 2021 May 26; Vol. 66 (11). Date of Electronic Publication: 2021 May 26.
DOI:	10.1088/1361-6560/abf811
Abstrakt:	In this work we show the first microdosimetry measurements on a low energy proton beam with therapeutic-equivalent fluence rates by using the second generation of 3D-cylindrical microdetectors. The sensors belong to an improved version of a novel silicon-based 3D-microdetector design with electrodes etched inside silicon, which were manufactured at the National Microelectronics Centre (IMB-CNM, CSIC) in Spain. A new microtechnology has been employed using quasi-toroid electrodes of 25 μ m diameter and a depth of 20 μ m within the silicon bulk, resulting in a well-defined cylindrical radiation sensitive volume. These detectors were tested at the 18 MeV proton beamline of the cyclotron at the National Accelerator Centre (CNA, Spain). They were assembled into an in-house low-noise readout electronics to assess their performance at a therapeutic-equivalent fluence rate. Microdosimetry spectra of lineal energy were recorded at several proton energies starting from 18 MeV by adding 50 μ m thick tungsten foils gradually at the exit-window of the cyclotron external beamline, which corresponds to different depths along the Bragg curve. The experimentalyF¯values in silicon cover from (5.7 ± 0.9) to (8.5 ± 0.4) keV  μ m -1 in the entrance to (27.4 ± 2.3) keV  μ m -1 in the distal edge. Pulse height energy spectra were crosschecked with Monte Carlo simulations and an excellent agreement was obtained. This work demonstrates the capability of the second generation 3D-microdetectors to assess accurate microdosimetric distributions at fluence rates as high as those used in clinical centers in proton therapy. (Creative Commons Attribution license.)
Databáze:	MEDLINE
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