Measurements and elimination of Cherenkov light in fiber-optic scintillating detector for electron beam therapy dosimetry

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2007-08, Vol.579 (1), p.344-348
• Main Authors: Lee, Bongsoo, Jang, Kyoung Won, Cho, Dong Hyun, Yoo, Wook Jae, Tack, Gye-Rae, Chung, Soon-Cheol, Kim, Sin, Cho, Hyosung
• Format: Article
• Language: English
• Subjects: Cherenkov light; Fiber-optic radiation detector; Scintillator
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2007.04.074

In this study, a miniature fiber-optic radiation detector has been developed using a water-equivalent organic scintillator for electron beam therapy dosimetry. Usually, two kinds of light signals such as fluorescent and Cherenkov lights are generated in a fiber-optic radiation detector when a high-energy electron beam is irradiated. The fluorescent light signal is produced in the scintillator and is transmitted through a plastic optical fiber to a remote light-measuring device such as a PMT or a photodiode. The Cherenkov light could be also produced in the plastic optical fiber itself and be detected by a light-measuring device. Therefore, it could cause problems or limit the accuracy of the detection of a fluorescent light signal that is proportional to dose. The objectives of this study are to measure, characterize and eliminate Cherenkov light generated in a plastic optical fiber used as a component of a fiber-optic radiation detector and to detect a real fluorescent light signal from the scintillator. In this study, the intensity of Cherenkov light is measured and characterized as a function of the incident angle of an electron beam from a LINAC, as a function of the electron beam energy, and as a function of electron beam size. Also, a subtraction method using a background optical fiber without a scintillator and an optical discrimination method using optical filters are investigated to remove Cherenkov light.