光声技术在医学成像中的应用

Three-dimensional ultrasonic imaging Photoacoustic technique and its application in medical imaging

现在的医学成像手段不能很好地探测乳腺癌中的小块肿瘤。对于癌症检测来说,光声成像技术是一种前景光明的成像技术。这一成像手段既有光学成像的高对比度,又有声学成像的高穿透深度,结合了二者的优点。在建立的光声成像系统中,采用532nm、脉宽10ns的脉冲激光器作为光源,产生超声信号。为了对系统在癌症检测中的能力进行评估,制作了一个由琼脂和intralipid制成的乳房组织模型。成像时,为了更容易探测到超声信号,组织模型和探测器放置在一个透明有机玻璃制成的水容器中。并且对超声信号进行滤波反投影处理,重建组织模型能量吸收的平面分布。实验结果表明,光声成像在早期的乳腺癌和其它癌症的检测中将会占有重要的位置。

Current medical imaging modalities fall to detect small tumors in the breast cancer. Photoacoustic tomography is a novel technique for early cancer detection with promising diagnostic capability. This imaging modality takes the advantages in that the tomography image has the optical contrast similar to the optical techniques while enjoying the high depth of penetration comparable to the ultrasound. A photoacoustic tomography experiment system has been constructed. In the system, a Q-switched Nd：YAG pulse laser operated at 532nm with a 10ns pulse width is employed to generate photoacoustic signal. A breast tissue-mimicking phantom was made of agar and intralipid to test the system capability in cancer detection. When imaged, the phantom and detectors were immersed in a water tank to facilitate the acoustic detection. Based on filter back-projection process of photoacoustic imaging, the two-dimension distribution of optical absorption in tissue phantom was reconstructed. The results suggest that the photoacoustic imaging may occupy a significant niche in early detection of cancer in the breast and other organs.