Innovative silicon detectors for measuring the energy of clinical proton beams: preliminary results

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Innovative silicon detectors for monitoring of proton beam energy: preliminary results.

Session Type Physics

Physics Topic: Da scegliere tra:

Beam delivery and nozzle design  messo l’anno scorso per MoVeIT contatore+ energia Commissioning new facilities

Absolute and relative dosimetry Quality assurance & Verification Treatment planning

Dose calculation and optimisation Image guidance

Monitoring and modelling motion 4D treatment and delivery Adaptive therapy

Presentation Preference: Oral Abstract Title

Innovative strip silicon detectors for proton beam monitoring: preliminary results. Authors

Massimo 10 autori  Ho tolto attili e manganaro

A. Vignati1_{, O. Hammad Ali}2_{, M. Donetti}3_{, F. Fausti}1_{, S. Giordanengo}1_{, F. Mas Milian}4_{, V. Monaco}2_{, R. Sacchi}2_{, Z.}

Shakarami2_{, R. Cirio}2_.

1_{National Institute for Nuclear Physics INFN, Turin division, Turin, Italy.}

2_{National Institute for Nuclear Physics INFN- Università degli Studi di Torino, Physics Department, Turin, Italy.} 3_{Fondazione CNAO, Medical Physics, Pavia, Italy.}

4 _{Affiliazione Felix}

Abstract Text

The MoVeIT project of the INFN is investigating the use of innovative silicon detectors optimized for time resolution (Ultra Fast Silicon Detectors - UFSDs) to assess the beam energy of clinical proton beams. The capability to detect single protons and the outstanding time resolution provided by UFSD technology (tenths of ps for 50 um thick sensors) are exploited to measure protons’ time-of-flight with a telescope of two sensors. The time-of-flight is calculated as the difference of times of arrival of the same proton in the two sensors, using constant fraction algorithms, and the corresponding beam energies at specific distances are obtained by taking into account the energy lost in the air between sensors, through an analytical

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approximation validated with Geant4 simulations. The preliminary results, obtained with two UFSDs (80 um active- and 150 um total-thickness; 3x3 mm2_{area, each) at relative distances ranging between 4 and 97 cm}

on a clinical proton beam with energies between 62 and 228 MeV, showed an error on the estimation of the energy of less than 1 MeV (at 228 MeV, 97 cm). Following these encouraging results, dedicated strip sensors were designed, produced and thinned to a total thickness of 100 um, in order to cover an area of 4x4 mm2

and simulations are ongoing to study the best combinatorial methods to identify coincidences among strips. The proposed device could not only monitor the beam energy online, but could be also essential to estimate the accelerator precision in changing energy, which is essential to investigate future developments towards tumor tracking strategies.