Microdosimetric study at the CNAO active-scanning carbon-ion beam

Paolo Colautti, Valeria Conte, Sabina Chiriotti Alvarez, Andrea Pola, Davide Bortot, Alberto Fazzi, Stefano Agosteo, Mario Ciocca

Research outputpeer-review


The Italian National Centre for Oncological Hadrontherapy (CNAO) has been treating patients since 2011 with carbon-ion beams using the active-scanning modality. In such irradiation modality, the beam spot, which scans the treatment area, is characterised by very high particle-fluence rates (more than 105 s−1 mm−2). Moreover, the Bragg-peak is only ~1 mm-FWHM. Commercial tissue-equivalent proportional counters (TEPC), like the Far West Technologies LET-½, are large, hence they have limited capability to measure at high counting fluence rates. In this study we have used two home-made detectors, a mini-TEPC 0.81 mm2 in sensitive area and a silicon telescope 0.125mm2 in sensitive area, to perform microdosimetric measurements in the therapeutic carbon-ion beam of CNAO. A monoenergetic carbon-ion beam of 189.5 ± 0.3 MeV/u scanning a 3 × 3 cm2 area has been used. Spectral differences are visible in the low y-value region, but the mean microdosimetric values, measured with the two detectors, result to be pretty consistent, as well as the microdosimetric spectra in the high yvalue region.
Original languageEnglish
Pages (from-to)157-161
Number of pages5
JournalRadiation protection dosimetry
Issue number1-4
StatePublished - 26 Oct 2017

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