Effects of Temperature and X-rays on Plastic Scintillating Fiber and Infrared Optical Fiber

Abstract

In this study, we have studied the effects of temperature and X-ray energy variations on the light output signals from two different fiber-optic sensors, a fiber-optic dosimeter (FOD) based on a BCF-12 as a plastic scintillating fiber (PSF) and a fiber-optic thermometer (FOT) using a silver halide optical fiber as an infrared optical fiber (IR fiber). During X-ray beam irradiation, the scintillating light and IR signals were measured simultaneously using a dosimeter probe of the FOD and a thermometer probe of the FOT. The probes were placed in a beaker with water on the center of a hotplate, under variation of the tube potential of a digital radiography system or the temperature of the water in the beaker. From the experimental results, in the case of the PSF, the scintillator light output at the given tube potential decreased as the temperature increased in the temperature range from 25 to 60 °C. We demonstrated that commonly used BCF-12 has a significant temperature dependence of −0.263 ± 0.028%/°C in the clinical temperature range. Next, in the case of the IR fiber, the intensity of the IR signal was almost uniform at each temperature regardless of the tube potential range from 50 to 150 kVp. Therefore, we also demonstrated that the X-ray beam with an energy range used in diagnostic radiology does not affect the IR signals transmitted via a silver halide optical fiber.

Temperature dependence of plastic scintillators

“…Later, in 2013 two papers [4,5] presented measurements on the BCF-12 and BCF-60 (also polystyrene based) reporting non-vanishing temperature coefficients for both scintillators. The results for BCF-12 have been confirmed by Lee et al in a work published in 2015 [6]. These works focused on the widely used BCF-12 and BCF-60 scintillators, being the information on other plastic scintillators scarce.…”

“…Except for BC-404, all the other scintillators present a clear temperature dependence within the measured range. The measured temperature coefficient value for BCF-10 is similar to the BCF-12 scintillator (α= (-2.6 ± 0.03) ×10 -3 ºC -1 ) [6] (also a blue-emitting scintillator [14]). On the other hand, the value obtained for the BCF-60 scintillator is less than the values reported by earlier works [4,5] of about 5×10 -3 ºC -1 , but still showing a significant decrease on light yield with temperature.…”

“…Ideally, the response from the dosimeter should be constant for a sufficiently wide range of temperatures. However, several studies now suggest that PSDs might have temperature dependency [3][4][5][6]. In order to correct the dosimeter readings, it is critical to study the scintillator's temperature dependence.…”

Characterization of a scintillating fibre detector for small animal imaging and irradiation dosimetry

“…The temperature inside the X-RAD® cabinet was stable during measurements (21 6 2°C). Thus, the uncertainty generated by the small temperature dependence of the BCF-12 light output (20.263 6 0.028%/°C reported by Lee et al 12 ) was not taken into account. It should not exceed 1% in our conditions.…”

“…9 Small dependence to temperature has also been reported with a small decrease of the plastic scintillator light output with increasing temperature. [10][11][12] This temperature dependence is an important consideration for a detector dedicated to in vivo dosimetry. Nevertheless, it becomes negligible in a temperature-controlled environment.…”