Dual Beam-Current Transformer Design for Monitoring and Reporting of Electron Ultra-High Dose Rate (Flash) Beam Parameters

Authors

Kevin Liu
Allison Palmiero
Nitish Chopra
Brett Velasquez
Ziyi Li
Sam Beddar
Emil Schüler

Publication Date

2-1-2023

Journal

Journal of Applied Clinical Medical Physics

Abstract

PURPOSE: To investigate the usefulness and effectiveness of a dual beam-current transformer (BCTs) design to monitor and record the beam dosimetry output and energy of pulsed electron FLASH (eFLASH) beams in real-time, and to inform on the usefulness of this design for future eFLASH beam control.

METHODS: Two BCTs are integrated into the head of a FLASH Mobetron system, one located after the primary scattering foil and the other downstream of the secondary scattering foil. The response of the BCTs was evaluated individually to monitor beam output as a function of dose, scattering conditions, and ability to capture physical beam parameters such as pulse width (PW), pulse repetition frequency (PRF), and dose per pulse (DPP), and in combination to determine beam energy using the ratio of the lower-to-upper BCT signal.

RESULTS: A linear relationship was observed between the absorbed dose measured on Gafchromic film and the BCT signals for both the upper and lower BCT (R

CONCLUSION: The dual BCT system integrated within the FLASH Mobetron was shown to be a reliable monitoring system able to quantify accelerator performance and capture all essential physical beam parameters on a pulse-by-pulse basis, and the ratio between the two BCTs was strongly correlated with beam energy. The fast signal readout and processing enables the BCTs to provide real-time information on beam output and energy and is proposed as a system suitable for accurate beam monitoring and control of eFLASH beams.

Keywords

Humans, Electrons, Radiometry, Radiotherapy Dosage, beam current transformers, dosimetry, FLASH, toroids

Comments

Supplementary Materials

PMID: 36601691