The availability of real-time treatment verification during high-dose-rate (HDR) brachytherapy is currently limited. Therefore, we studied the luminescence properties of the widely commercially available scintillators using the inorganic materials Eu-activated phosphors Y2O3:Eu, YVO4:Eu, Y2O2S:Eu, and Gd2O2S:Eu to determine whether they could be used to accurately and precisely verify HDR brachytherapy doses in real time. The suitability for HDR brachytherapy of inorganic scintillation detectors (ISDs) based on the 4 Eu-activated phosphors in powder form was determined based on experiments with a 192Ir HDR brachytherapy source. The scintillation intensities of the phosphors were 16 to 134 times greater than that of the commonly used organic plastic scintillator BCF-12. High signal intensities were achieved with an optimized packing density of the phosphor mixture and with a shortened fiber-optic cable. The influence of contaminating Cerenkov and fluorescence light induced in the fiber-optic cable (stem signal) was adequately suppressed by inserting between the fiber-optic cable and the photodetector a 25-nm band-pass filter centered at the emission peak. The spurious photoluminescence signal induced by the stem signal was suppressed by placing a long-pass filter between the scintillation detector volume and the fiber-optic cable. The time-dependent luminescence properties of the phosphors were quantified by measuring the non-constant scintillation during irradiation and the afterglow after the brachytherapy source had retracted. We demonstrated that a mixture of Y2O3:Eu and YVO4:Eu suppressed the time-dependence of the ISDs and that the time-dependence of Y2O2S:Eu and Gd2O2S:Eu introduced large measurement inaccuracies. We conclude that ISDs based on a mixture of Y2O3:Eu and YVO4:Eu are promising candidates for accurate and precise real-time verification technology for HDR BT that is cost effective and straightforward to manufacture. Widespread dissemination of this technology could lead to an improved understanding of error types and frequencies during BT and to improved patient safety during treatment.
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机译:目前在高剂量率(HDR)近距离放射治疗期间进行实时治疗验证的能力有限。因此,我们研究了使用无机材料Eu活化磷光体Y2O3:Eu,YVO4:Eu,Y2O2S:Eu和Gd2O2S:Eu的市售闪烁体的发光特性,以确定它们是否可用于准确,准确地验证HDR近距离放射治疗是实时的。基于 192 sup> Ir HDR近距离放射源的实验,确定了基于4种粉状Eu活化磷的无机闪烁探测器(ISD)的HDR近距离放射治疗的适用性。磷光体的闪烁强度是通常使用的有机塑料闪烁体BCF-12的16至134倍。通过优化磷光体混合物的堆积密度和缩短光纤电缆,可以实现高信号强度。通过在光缆和光电探测器之间插入一个以发射峰为中心的25 nm带通滤波器,可以充分抑制污染Cerenkov和在光缆中引起的荧光(干信号)的影响。通过在闪烁检测器体积和光缆之间放置一个长通滤波器,可以抑制由干信号引起的寄生光致发光信号。通过测量照射过程中的非恒定闪烁以及近距离放射治疗源撤回后的余辉,可以定量荧光粉的时间依赖性发光特性。我们证明了Y2O3:Eu和YVO4:Eu的混合物抑制了ISD的时间依赖性,并且Y2O2S:Eu和Gd2O2S:Eu的时间依赖性引入了很大的测量误差。我们得出的结论是,基于Y2O3:Eu和YVO 4 sub>:Eu的混合物的ISD有望成为HDR BT准确,实时的实时验证技术的候选者,该技术经济高效且易于制造。这项技术的广泛传播可以提高对BT期间错误类型和频率的了解,并提高治疗期间的患者安全性。
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