A beam monitor using silicon pixel sensors for hadron therapy

TL;DR

This paper presents a silicon pixel sensor-based beam monitor for hadron therapy, capable of real-time, high-precision measurements of beam position, angle, and intensity with minimal radiation damage.

Contribution

The study introduces a novel beam monitor using Topmetal-II- sensors that allows non-invasive, high-resolution monitoring of heavy ion beams in hadron therapy.

Findings

Achieved position resolution better than 20 μm

Angular resolution approximately 0.5°

Intensity measurement accuracy better than 2%

Abstract

We report the design and test results of a beam monitor developed for online monitoring in hadron therapy. The beam monitor uses eight silicon pixel sensors, \textit{Topmetal-${II}^-$}, as the anode array. \textit{Topmetal-${II}^-$} is a charge sensor designed in a CMOS 0.35 $\mu$m technology. Each \textit{Topmetal-${II}^-$} sensor has $72\times72$ pixels and the pixel size is $83\times83$ $\mu$m$^2$. In our design, the beam passes through the beam monitor without hitting the electrodes, making the beam monitor especially suitable for monitoring heavy ion beams. This design also reduces radiation damage to the beam monitor itself. The beam monitor is tested with a carbon ion beam at the Heavy Ion Research Facility in Lanzhou (HIRFL). Results indicate that the beam monitor can measure position, incidence angle and intensity of the beam with a position resolution better than 20 $\mu$m, angular resolution about 0.5$^\circ$ and intensity statistical accuracy better than 2$\%$.