Imaging Physics Laboratory, Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA.
Phys Med Biol. 2012 Mar 21;57(6):1575-93. doi: 10.1088/0031-9155/57/6/1575. Epub 2012 Mar 7.
As x-ray imaging technology moves from conventional radiography and computed tomography (CT) to spectral radiography and CT, dedicated phantom materials are needed for spectral imaging. The spectral phantom materials should accurately represent the energy-dependent mass-attenuation coefficients of different types of tissues. Although tissue-equivalent phantom materials were previously developed for CT and radiation therapy applications, these materials are suboptimal for spectral radiography and CT; they are not compatible with contrast agents, do not represent many of the tissue types and do not provide accurate values of attenuation characteristics of tissue. This work provides theoretical framework and a practical method for developing tissue-equivalent spectral phantom materials with a required set of parameters. The samples of the tissue-equivalent spectral phantom materials were developed, tested and characterized. The spectral phantom materials were mixed with iodine, gold and calcium contrast agents and evaluated. The materials were characterized by CT imaging and x-ray transmission experiments. The fabricated materials had nearly identical densities, mass attenuation coefficients, effective atomic numbers and electron densities as compared to corresponding tissue materials presented in the ICRU-44 report. The experimental results have shown good volume uniformity and inter-sample uniformity (repeatability of sample fabrication) of the fabricated materials. The spectral phantom materials were fabricated under laboratory conditions from readily available and inexpensive components. It was concluded that the presented theoretical framework and fabrication method of dedicated spectral phantom materials could be useful for researchers and developers working in the new area of spectral radiography and CT. Independently, the results could also be useful for other applications, such as radiation therapy.
随着 X 射线成像技术从传统的放射摄影和计算机断层扫描（CT）发展到光谱放射摄影和 CT，需要专门的幻影材料来进行光谱成像。光谱幻影材料应准确地代表不同类型组织的能量相关质量衰减系数。虽然之前已经为 CT 和放射治疗应用开发了组织等效幻影材料，但这些材料对于光谱放射摄影和 CT 来说并不理想；它们与造影剂不兼容，不能代表许多组织类型，也不能提供组织衰减特性的准确值。这项工作为开发具有所需参数的组织等效光谱幻影材料提供了理论框架和实用方法。开发、测试和表征了组织等效光谱幻影材料的样品。将光谱幻影材料与碘、金和钙造影剂混合并进行了评估。通过 CT 成像和 X 射线透射实验对材料进行了表征。与 ICRU-44 报告中给出的相应组织材料相比，所制备的材料具有几乎相同的密度、质量衰减系数、有效原子数和电子密度。实验结果表明，所制备的材料具有良好的体积均匀性和样品间均匀性（样品制备的重复性）。光谱幻影材料是在实验室条件下用现成的、廉价的成分制造的。得出的结论是，所提出的专用光谱幻影材料的理论框架和制造方法对于从事光谱放射摄影和 CT 这一新领域的研究人员和开发人员可能是有用的。独立地，这些结果也可能对其他应用领域有用，例如放射治疗。
