Significance: Gas in scattering media absorption spectroscopy (GASMAS) is a technique for gas sensing in cavities surrounded by scattering materials. GASMAS could be translated to the clinic to monitor lung function continuously and noninvasively in neonates. Accurate tissue phantoms are essential to assess the strengths and limitations of gas spectroscopy in gas-containing cavities in the human body. Aim: The aim is to develop a detailed protocol to produce a long-lasting, multistructure tissue phantom of the thorax of a neonate. The phantom mimics the geometry and the optical properties of the main organs of the thorax and has an empty pulmonary cavity that facilitates GASMAS monitoring of gas content. Approach: The anatomic geometry of heart, lungs, bones, muscle, fat, and skin was obtained from a neonatal computed tomography scan. Once segmented, organs were 3D printed and used to create negative rubber molds. The entire thorax was built in phantom material (silicone as matrix, black ink as absorber, and silica microspheres as scatters) by placing all phantom organs inside the muscle structure. Our phantom recipe was customized by mixing specific ratios of ink and spheres to match the optical properties of the different organs that were consider to be homogeneous. Results: An anthropomorphic thorax phantom with the desired optical properties (μa and μs′) at 760 nm was built and used to obtain “transdermal” GASMAS measurements of oxygen content within the lung cavity. Conclusion: A protocol to build a robust optical phantom of the thorax of a neonate was used to conduct benchtop studies. This recipe can be implemented to reproduce the geometry and optical properties of any human or animal tissue.

中文翻译：

---

新生儿胸部拟人化光学模型：早产儿肺部研究的关键工具

意义：散射介质中气体吸收光谱 (GASMAS) 是一种在散射材料包围的空腔中进行气体传感的技术。GASMAS 可以应用于临床，以连续、无创的方式监测新生儿的肺功能。准确的组织模型对于评估人体含气腔内气体光谱的优点和局限性至关重要。目的：目的是制定详细的方案来制作新生儿胸部的持久、多结构组织模型。该体模模仿了胸部主要器官的几何形状和光学特性，并具有一个空的肺腔，有利于 GASMAS 监测气体含量。方法：通过新生儿计算机断层扫描获得心脏、肺、骨骼、肌肉、脂肪和皮肤的解剖几何形状。分割后，器官将被 3D 打印并用于创建负橡胶模具。整个胸部是用幻影材料（硅胶作为基质，黑色墨水作为吸收剂，二氧化硅微球作为散射体）构建的，将所有幻影器官放置在肌肉结构内。我们的模型配方是通过混合特定比例的墨水和球体来定制的，以匹配被认为是同质的不同器官的光学特性。结果：构建了一个在 760 nm 处具有所需光学特性（μa 和 μs'）的拟人化胸部模型，并用于获得肺腔内氧含量的“经皮”GASMAS 测量。结论：使用构建新生儿胸部坚固光学模型的方案来进行台式研究。该配方可用于重现任何人类或动物组织的几何形状和光学特性。