Darafsheh Arash, Zhang Rongxiao, Kanick Stephen Chad, Pogue Brian W, Finlay Jarod C
University of Pennsylvania, Department of Radiation Oncology, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania 19104, United States.
Dartmouth College, Department of Physics and Astronomy, Hanover, New Hampshire 03755, United States.
J Biomed Opt. 2015 Sep;20(9):095001. doi: 10.1117/1.JBO.20.9.095001.
We have investigated Čerenkov radiation generated in phosphor-based optical fiber dosimeters irradiated with clinical electron beams. We fabricated two high-spatial resolution fiber-optic probes, with 200 and 400 μm core diameters, composed of terbium-based phosphor tips. A generalizable spectroscopic method was used to separate Čerenkov radiation from the transmitted signal by the fiber based on the assumption that the recorded signal is a linear superposition of two basis spectra: characteristic luminescence of the phosphor medium and Čerenkov radiation. We performed Monte Carlo simulations of the Čerenkov radiation generated in the fiber and found a strong dependence of the recorded Čerenkov radiation on the numerical aperture of the fiber at shallow phantom depths; however, beyond the depth of maximum dose that dependency is minimal. The simulation results agree with the experimental results for Čerenkov radiation generated in fibers. The spectroscopic technique used in this work can be used for development of high-spatial resolution fiber micro dosimeters and for optical characterization of various scintillating materials, such as phosphor nanoparticles, in ionizing radiation fields of high energy.
我们研究了临床电子束照射基于磷光体的光纤剂量计中产生的切伦科夫辐射。我们制作了两个具有200和400μm芯径的高空间分辨率光纤探头，其由基于铽的磷光体尖端组成。基于记录信号是两个基谱的线性叠加这一假设，即磷光体介质的特征发光和切伦科夫辐射，采用一种可推广的光谱方法从光纤传输信号中分离出切伦科夫辐射。我们对光纤中产生的切伦科夫辐射进行了蒙特卡罗模拟，发现在浅模体深度处记录的切伦科夫辐射对光纤数值孔径有很强的依赖性；然而，在最大剂量深度之外，这种依赖性最小。模拟结果与光纤中产生的切伦科夫辐射的实验结果一致。这项工作中使用的光谱技术可用于开发高空间分辨率光纤微剂量计，以及用于在高能电离辐射场中对各种闪烁材料（如磷光体纳米颗粒）进行光学表征。
