Photoacoustic imaging, which can provide the maximum intensity contrast in tissue depth imaging without ionizing radiation, will be a promising imaging trend for tumor detection. In this paper, a column diffusion fiber was employed to carry a pulsed laser for irradiating stomach directly through esophagus based on the characteristics of gastric tissue structure. A long focused ultrasonic transducer was placed outside the body to detect photoacoustic signals of gastric tissue. Phantom and in vitro experiments of submucosal gastric tumors were carried out to check the sensitivity of scanning photoacoustic tomography system, including the lateral and longitudinal resolution of the system, sensitivity of different absorption coe±cient in imaging, capability of transversal detection, and probability of longitudinal detection. The results demonstrate that our innovative technique can improve the parameters of imaging. The lateral resolution reaches 2.09 mm. Then a depth of 5.5mm with a longitudinal accuracy of 0.36mm below gastric mucosa of early gastric cancer (EGC) has been achieved. In addition, the optimal absorption coe±cient differences among absorbers of system are 3.3–3.9 times. Results indicate that our photoacoustic imaging (PAI) system, is based on a long focusing transducer, can provide a potential application for detecting submucosal EGC without obvious symptoms.

Determination of light absorption distribution in the prostate tissue irradiated by diffusing light source is important for the treatment planning. In this paper, a three-dimensional (3D) optical model of human prostate is developed, and the light absorption distribution in the prostate tissue is estimated by Monte Carlo simulation method. Light distribution patterns including 3D distributions in the tissue model irradiated by two diffusing light sources are obtained and compared. Also, the impacts of length and energy of cylinder diffusing light source on the irradiance volume are demonstrated. Those results will be significant for the nondestructive qualitative assessments of photodosimetry in biomedical phototherapy.

光学遥感的邻近效应可以看作大气点扩散函数(PSF)和地表辐射场的卷积, 通过逆向蒙特卡罗法模拟大气PSF, 利用辐射传输模型MODTRAN计算地表辐射场, 获得遥感器入瞳处的辐亮度值.开展不同对比度目标背景物在典型条件下的邻近效应模拟与分析, 结果显示: 目标和背景的反射率分布对邻近效应影响很大, 背景反射率越大, 邻近效应占总辐射的比例越高; 暗目标在亮背景下的邻近效应明显大于亮目标在暗背景下的邻近效应; 固定成像高度和区域, 空间分辨率越高, 邻近效应越明显; 地面气象视距对邻近效应的影响非常显著, 气象视距增大, 邻近效应减弱; 太阳天顶角增大, 邻近效应减弱.模拟结果为高分辨率光学遥感成像系统高精度建模和邻近效应校正算法研究提供了依据.

针对光学遥感成像系统的全链路仿真在我国刚刚起步。通过分析能量在大气、场景和遥感器之间传递时发生的各种相互作用，将整个仿真过程分为三维场景构建与组织、遥感器 入瞳处辐亮度图像模拟、遥感器效果模拟三部分，分析了框架中各个模块的功能和模块之间的概念数据流向。最后分析了地形起伏和观测角度变化对成像的影响。 计算显示：像元高度从0增至1 km时，入瞳处辐亮度的最大相对差异可达170%;观测天顶角从180°变为124.4°时，辐亮度的相对差异最大可接近50%。

光声成像技术是生物医学领域中新兴的无损检测技术，具有对比度高、分辨率好、穿透能力强等优点。本文介绍了光声成像技术近年来的进展状况，主要涉及成像探测方式的改进、成像速度的加快、成像分辨率的提高以及图像重构算法的发展等。以该项技术在现代临床诊断中的应用为例，描述了其在生物医学领域中应用范围的拓宽。最后，总结了该项技术现存的主要问题，指出多模式组合的成像方式，如光声与超声的组合，光声与OCT方式的组合是该项技术的发展趋势; 另外，结合造影剂的分子光声成像技术也同样很有发展前景。