光声成像技术近年来已成为一种极具前景的前列腺癌成像技术。由于光声成像范围与光能量的吸收分布直接相关，为了优化经尿道光辐照的前列腺光声成像系统的光源参数，必须了解前列腺组织的光吸收分布。根据前列腺组织的形态特征构建了一个嵌有球状肿瘤的三维前列腺光学模型，利用光学分子影像仿真平台(MOSE) 比较研究了柱状和球状两种弥散光源经尿道辐照时组织内光吸收分布特性。考查了激光能量和肿瘤处光学吸收系数对肿瘤光吸收的影响。模拟结果表明经尿道照明有利于前列腺组织内部光吸收，特别是深处位置。另外，相比于球状弥散光源，柱状弥散光源侧向光吸收分布较均匀，适合于三维扫描光声成像和信源分析。研究结果表明增大输入的激光能量或者肿瘤光学吸收系数可以明显提高肿瘤处光能量吸收，这与组织光学中的有关理论一致。有关结论有助于前列腺光声成像系统的光源优化设计和成像深度的改善。

Photoacoustic imaging has recently emerged as a promising imaging modality for prostate cancer. Knowledge of absorbed light distribution in prostate tissues is essential since the distribution characteristics of absorbed light energy will influence the imaging depth and range of photoacoustic imaging (PAI). In this paper, a tumor-embedded prostate optical model was established. Light absorption distribution patterns of the tissue model through trans-urethral laser illumination using cylindrical diffusing light (CDL) and spherical diffusing light (SDL) were studied based on the Molecular Optical Simulation Environment (MOSE). In addition, the influence of laser energy and absorption coefficient of tumor on the light absorption in tumor was demonstrated. The results show that laser illumination from urethral allows the prostate tissues to obtain more efficient light absorption. The light absorption distribution of tumors irradiated by CDL has a relatively uniform characteristic in a large range, with its value around the light source less than that of SDL. Laser energy and tumor absorption coefficient has linear effect on the light absorption of tumor, which is consistent with the Beer Law. The conclusions will be helpful to optimize the laser source and to improve the imaging depth in a photoacoustic imaging system.