We present a systematical study on comparison between water and dry coupling in photoacoustic tomography of the human finger joints. Compared to the direct water immersion of the finger for water coupling, the dry coupling is realized through a transparent PDMS film-based water bag, which ensures water-free contact with the skin. The results obtained suggest that the dry coupling provides image quality comparable to that by water coupling while eliminating the wrinkling of the finger joint caused by the water immersion. In addition, the dry coupling offers more stable hemodynamic images than the water coupling as the water immersion of the finger joint causes reduction in blood vessel size.

中文翻译：

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指关节光声层析成像中水与干耦合的对比研究

我们对人体手指关节光声断层扫描中水和干耦合之间的比较进行了系统研究。与手指直接浸水进行水耦合相比，干耦合是通过透明的PDMS薄膜基水袋实现的，确保与皮肤无水接触。获得的结果表明，干耦合提供了与水耦合相当的图像质量，同时消除了因水浸引起的手指关节起皱。此外，干式耦合比水耦合提供更稳定的血流动力学图像，因为手指关节的水浸会导致血管尺寸减小。