Medipix3 proton and carbon ion measurements across full energy ranges and at clinical flux rates in MedAustron IR1

TL;DR

This study evaluates the Medipix3 detector's performance in measuring proton and carbon ion beams across a wide energy range at clinical flux rates, demonstrating its linearity, high resolution, and radiation resilience for use in ion therapy beam monitoring.

Contribution

The paper provides comprehensive characterization of Medipix3 for proton and carbon ion detection at clinical fluxes, including beam profile, intensity, linearity, and radiation damage assessment, which was previously unreported.

Findings

Count rate linearity within uncertainties for non-degrader measurements.

Identification of specific frequency components in beam intensity fluctuations.

No conclusive long-term radiation damage observed after one day of operation.

Abstract

The Medipix3, a hybrid pixel detector with a silicon sensor, has been evaluated as a beam instrumentation device with proton and carbon ion measurements in the non-clinical research room (IR1) of MedAustron Ion Therapy Center. Protons energies are varied from 62.4 to 800 MeV with $10^{4}$ to $10^{8}$ protons per second impinging on the detector surface. For carbon ions, energies are varied from 120 to 400 MeV/amu with $10^{7}$ to $10^{8}$ carbon ions per second. Measurements include simultaneous high resolution, beam profile and beam intensity with various beam parameters at up to 1000 FPS (frames per second), count rate linearity and an assessment of radiation damage after the measurement day using an x-ray tube to provide a homogeneous radiation measurement. The count rate linearity is found to be linear within the uncertainties (dominated by accelerator related sources due to special setup) for the measurements without degraders. Various frequency components are identified within the beam intensity over time firstly including 49.98 Hz with standard deviation, $\sigma=0.29$, secondly 30.55 Hz $\sigma=0.55$ and thirdly 252.51 Hz $\sigma=0.83$. A direct correlation between the number of zero counting and noisy pixels is observed in the measurements with the highest flux. No conclusive evidence of long term radiation damage was found as a result of these measurements over one day.