Development of a scintillation screen monitor and emittance measurement experiment at the National Cancer Center Korea

Abstract

This study presents a beam profile monitor composed of a vacuum chamber housing, a scintillator screen, a digital camera, and a custom control circuit based on Raspberry Pi for an accurate measurement of beam profiles with a high spatial resolution which is crucial for beam quality assessment and control for the therapeutic beamline. A simple position calibration that uses perspective transform was conducted to map from the pixel space to real space. Additionally, we investigated finding a proper noise filtering methods to mitigate stray and impulsive noises. We found that the non-local de-noising algorithm outperformed than median filter for reducing noise in a high-frequency region. As a demonstration of utilization of the profile monitor, we measured transverse beam emittances along the x and y axes using quadrupole scanning technique, which were resulted in 2.715 ± 0.017 and 4.619 ± 0.018 π mm mrad, respectively.