Prog Med Phys.  2022 Dec;33(4):108-113. 10.14316/pmp.2022.33.4.108.

Feasibility Test of Flat-Type Faraday Cup for UltrahighDose-Rate Transmission Proton Beam Therapy

• Pak Si
• Cho S
• An S
• Jeong S
• Shin D
• Lim Y
• Jeong JH
• Kim H
• Lee SB

• KMID: 2537878
• DOI: http://doi.org/10.14316/pmp.2022.33.4.108

Abstract

Purpose
Proton therapy has been used for optimal cancer treatment by adapting its Bragg-peak characteristics. Recently, a tissue-sparing effect was introduced in ultrahigh-dose-rate (FLASH) radiation; the high-energy transmission proton beam is considered in proton FLASH therapy. In measuring high-energy/ultrahigh-dose-rate proton beam, Faraday Cup is considered as a doserate-independent measurement device, which has been widely studied. In this paper, the feasibility of the simply designed Faraday Cup (Poor Man’s Faraday Cup, PMFC) for transmission proton FLASH therapy is investigated.
Methods
In general, Faraday cups were used in the measurement of charged particles. The simply designed Faraday Cup and Advanced Markus ion chamber were used for high-energy proton beam measurement in this study.
Results
The PMFC shows an acceptable performance, including accuracy in general dosimetric tests. The PMFC has a linear response to the dose and dose rate. The proton fluence was decreased with the increase of depth until the depth was near the proton beam range. Regarding secondary particles backscatter from PMFC, the effect was negligible.
Conclusions
In this study, we performed an experiment to investigate the feasibility of PMFC for measuring high-energy proton beams. The PMFC can be used as a beam stopper and secondary monitoring system for transmission proton beam FLASH therapy.

Keyword

Proton beam therapy; Faraday cup; FLASH