Hybrid x-ray/optical luminescence imaging: Characterization of experimental conditions
Hybrid x-ray/optical luminescence imaging: Characterization of experimental conditions
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DOI：
10.1118/1.3457332
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发表时间：
2010-08-01
期刊：
影响因子：
3.8
通讯作者：
Xing, L.
中科院分区：
文献类型：
--
作者：
Carpenter, C. M.;Sun, C.;Xing, L.
目的：利用融合X射线成像和光学成像的双模式成像系统，研究X射线发光成像的可行性。这种方式利用X射线激活的纳米荧光粉，当被电离光子激发时发光。通过在荧光粉中掺杂稀土元素，在可见光和近红外范围内发光，这种发光适合于生物应用。这项研究考察了这种新模式的实际方面，包括磷光体浓度、光发射线性度、探测器损坏和光谱发射特性。方法：研究了掺Tb(绿光)和Eu(红光)的Gd和La氧化物硫化物荧光粉。光发射在临床X射线扫描仪中成像，带有冷却的CCD相机和分光光度计；剂量测量由校准的剂量计确定。使用这些属性，除了在文献中找到的类似荧光粉的发光效率值之外，还执行最小浓度计算。最后，2.5厘米的琼脂模型，直径1厘米的圆柱形。结果：在所选择的成像几何条件下，所选成像几何条件下的摄像机的剂量小于0.02cGy/S，发射光与剂量(R2=1)和浓度(R2=1)呈线性关系。临床X射线能量的发射峰值在半高处小于3 nm全宽，正如稀土掺杂所预期的那样。检测荧光粉所需的最低实际浓度取决于剂量；据估计，在典型的乳房X光照相剂量下，亚皮下摩尔浓度可在组织表面检测到，最小可检测浓度随深度增加而减少。在反射几何结构中，X射线发光与背景的对比度几乎是X射线透视的430倍。结论：X射线发光有望成为一种在X射线扫描仪中实现分子成像的新方式。尽管需要做很多工作来确保X射线激发荧光粉的生物兼容性，但这项工作中强调的这种方式的好处鼓励了进一步的研究。(C)2010年美国医学物理学家协会。[DOI：10.1118/1.3457332]
Purpose: The feasibility of x-ray luminescence imaging is investigated using a dual-modality imaging system that merges x-ray and optical imaging. This modality utilizes x-ray activated nanophosphors that luminesce when excited by ionizing photons. By doping phosphors with lanthanides, which emit light in the visible and near infrared range, the luminescence is suitable for biological applications. This study examines practical aspects of this new modality including phosphor concentration, light emission linearity, detector damage, and spectral emission characteristics. Finally, the contrast produced by these phosphors is compared to that of x-ray fluoroscopy.Methods: Gadolinium and lanthanum oxysulfide phosphors doped with terbium (green emission) or europium (red emission) were studied. The light emission was imaged in a clinical x-ray scanner with a cooled CCD camera and a spectrophotometer; dose measurements were determined with a calibrated dosimeter. Using these properties, in addition to luminescence efficiency values found in the literature for a similar phosphor, minimum concentration calculations are performed. Finally, a 2.5 cm agar phantom with a 1 cm diameter cylindrical. phosphor-filled inclusion (diluted at 10 mg/ml) is imaged to compare x-ray luminescence contrast with x-ray fluoroscopic contrast at a superficial location.Results: Dose to the CCD camera in the chosen imaging geometry was measured at less than 0.02 cGy/s. Emitted light was found to be linear with dose (R-2=1) and concentration (R-2=1). Emission peaks for clinical x-ray energies are less than 3 nm full width at half maximum, as expected from lanthanide dopants. The minimum practical concentration necessary to detect luminescent phosphors is dependent on dose; it is estimated that subpicomolar concentrations are detectable at the surface of the tissue with typical mammographic doses, with the minimum detectable concentration increasing with depth and decreasing with dose. In a reflection geometry, x-ray luminescence had nearly a 430-fold greater contrast to background than x-ray fluoroscopy.Conclusions: X-ray luminescence has the potential to be a promising new modality for enabling molecular imaging within x-ray scanners. Although much work needs to be done to ensure bio-compatibility of x-ray exciting phosphors, the benefits of this modality, highlighted in this work, encourage further study. (C) 2010 American Association of Physicists in Medicine. [DOI: 10.1118/1.3457332]