普通摄像机图像引导的放射治疗技术

Technique of image guided radiotherapy with conventional video cameras

图像引导放疗是精准放疗的关键点之一,常规利用X射线的图像引导技术在使用时会带给患者额外的辐射剂量,因此本文研究了一种没有任何副作用的普通摄像机图像引导放疗的技术。将3台普通摄像机安装在实验室内,获取摄像机实时图像,通过设计的自适应背景剔除算法删除图像背景获取感兴趣区域(ROI),在ROI图像内使用本文改进的ORB角点提取配准算法获取患者实时摆位信息,引导并验证患者摆位。设计光学图像提取患者呼吸信号算法引导运动器官肿瘤的治疗。将一套放疗用热塑膜固定的仿真体模放置在实验室中模拟患者治疗,通过多次测试,证明了本技术患者摆位偏移量精度为1mm和1°。通过一套呼吸运动模拟装置测试本文设计的呼吸运动信号提取算法,获得的呼吸运动信号和设定的信号在时间和幅度上达到96%以上的符合度。通过实验室内体模的测试,本技术基本满足图像引导放疗的技术要求。

Image guidance plays a major role in precision radiotherapy. Because conventional X-ray image guided techniques used in radiotherapy deliver additional doses to patient,an image guided radiation therapy (IGRT) technique using conventional video cameras that does not cause harm to the patient was investigated in this study. Three conventional video cameras were installed in different directions to acquire real-time images. The backgrounds of the images were deleted using an adaptive background removal algorithm designed in this study,and then the region of interest was obtained. Real-time patient positioning information could be achieved using an oriented FAST and rotated BRIEF algorithm that we modified. Respiratory signals were derived from the real-time images of the conventional video cameras using an algorithm we designed. A plastic patient model immobilized with a thermoplastic shell on a simulation couch was used to verify the accuracy and feasibility of our method. Test results show that the position and angle offset errors identified with our system are less than1 mm and1°,respectively. A respiratory motion simulator is designed and used to test the respiratory signal acquirement algorithm we designed. The time and amplitude conformity of the respiratory signals between the setting and acquirement is better than 96%. In our laboratory tests,the developed IGRT technique is shown to satisfy the requirements of image guided radiotherapy.