Department of Nuclear, Plasma and Radiological Engineering, The University of Illinois at Urbana-Champaign, 111E Talbot Lab, 104 S Wright St, Urbana, IL 61822, United States of America.
Phys Med Biol. 2019 Jan 31;64(3):035020. doi: 10.1088/1361-6560/aaeec3.
In this study, we have investigated the possibility of modulating x-ray fluorescence (XF) and x-ray luminescence (XL) emissions from therapeutic nanoparticles (NPs) by fine-tuning the energy of incident x-rays from benchtop x-ray sources. We have carried out detailed experimental studies to determine the strength of XF and XL emissions from YO:Eu and LaF:Tb NPs being irradiated with x-rays from benchtop x-ray sources operated with different tube-voltages and coupled to various filter configurations. These studies demonstrated that low-energy x-rays with average energy at around 10-15 keV are the most efficient to stimulate XL emission from the YO:Eu and LaF:Tb NPs. The efficiency falls quickly when x-ray energies go above or below the optimum energy range. As one would expect, x-rays with average energy just above the corresponding absorption edge of the target metal would be the most efficient in inducing XF emission. In this study, we have also demonstrated that one could fine-tune the incident x-ray energy to modulate the XL and XF emissions, such as (a) selectively inducing either XL or XF emission from the same type of NPs, (b) inducing preferential XL activation of YO:Eu over LaF:Eu or controlling the ratio of XL activation of these two types of NPs, and (c) introducing preferential XF emission from one type of NPs over the other. As a potential application, one could optimize the energy-characteristics of the incident x-rays to facilitate multiplexed combinatorial delivery of photodynamic therapy (X-PDT), where different agents could be administrated and then selectively activated in user-defined spatial and temporal patterns to fulfill combinatorial therapeutic effects. The understanding gained through this study could prove critical for enhancing the therapeutic delivery in X-PDT, and for attaining high-quality x-ray fluorescence computed tomography (XFCT) and x-ray luminescence computed tomography (XLCT) images while minimizing the x-ray dose to the sample.
在这项研究中，我们通过微调台式 X 射线源入射 X 射线的能量，研究了调节治疗性纳米颗粒（NPs）的 X 射线荧光（XF）和 X 射线发光（XL）发射的可能性。我们进行了详细的实验研究，以确定用不同管电压操作的台式 X 射线源和耦合到各种滤光片配置的 X 射线辐照的 YO:Eu 和 LaF:Tb NPs 的 XF 和 XL 发射强度。这些研究表明，平均能量在 10-15keV 左右的低能 X 射线最有效地刺激 YO:Eu 和 LaF:Tb NPs 的 XL 发射。当 X 射线能量高于或低于最佳能量范围时，效率迅速下降。正如人们所预期的那样，平均能量略高于目标金属相应吸收边的 X 射线最有效地诱导 XF 发射。在这项研究中，我们还证明可以通过微调入射 X 射线能量来调节 XL 和 XF 发射，例如：（a）选择性地从同种 NPs 中诱导 XL 或 XF 发射；（b）诱导 YO:Eu 相对于 LaF:Eu 的优先 XL 激活，或控制这两种类型的 NPs 的 XL 激活的比率；（c）从一种类型的 NPs 中优先诱导 XF 发射。作为一种潜在的应用，可以优化入射 X 射线的能量特性，以促进光动力疗法（X-PDT）的组合式递药，其中可以给予不同的试剂，然后以用户定义的空间和时间模式选择性地激活它们，以实现组合治疗效果。通过这项研究获得的认识对于增强 X-PDT 中的治疗性药物递送，以及获得高质量的 X 射线荧光计算机断层扫描（XFCT）和 X 射线发光计算机断层扫描（XLCT）图像，同时将 X 射线剂量最小化到样品，都可能具有至关重要的意义。
