Wang Michael, Rohling Robert, Duzenli Cheryl, Clark Brenda, Archip Neculai
Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, Canada.
Ultrasound Med Biol. 2008 Dec;34(12):1944-56. doi: 10.1016/j.ultrasmedbio.2008.06.001. Epub 2008 Aug 23.
A method for validating the start-to-end accuracy of a 3-D ultrasound (US)-based patient positioning system for radiotherapy is described. A radiosensitive polymer gel is used to record the actual dose delivered to a rigid phantom after being positioned using 3-D US guidance. Comparison of the delivered dose with the treatment plan allows accuracy of the entire radiotherapy treatment process, from simulation to 3-D US guidance, and finally delivery of radiation, to be evaluated. The 3-D US patient positioning system has a number of features for achieving high accuracy and reducing operator dependence. These include using tracked 3-D US scans of the target anatomy acquired using a dedicated 3-D ultrasound probe during both the simulation and treatment sessions, automatic 3-D US-to-US registration and use of infrared LED (IRED) markers of the optical position-sensing system for registering simulation computed tomography to US data. The mean target localization accuracy of this system was 2.5 mm for four target locations inside the phantom, compared with 1.6 mm obtained using the conventional patient positioning method of laser alignment. Because the phantom is rigid, this represents the best possible set-up accuracy of the system. Thus, these results suggest that 3-D US-based target localization is practically feasible and potentially capable of increasing the accuracy of patient positioning for radiotherapy in sites where day-to-day organ shifts are greater than 1 mm in magnitude.
描述了一种用于验证基于三维超声（US）的放射治疗患者定位系统端到端准确性的方法。使用一种放射敏感聚合物凝胶来记录在三维超声引导下定位后传递到刚性体模的实际剂量。将传递的剂量与治疗计划进行比较，可以评估从模拟到三维超声引导，最后到放射治疗的整个放射治疗过程的准确性。三维超声患者定位系统具有许多实现高精度和减少操作者依赖性的特征。这些特征包括在模拟和治疗过程中使用专用三维超声探头获取目标解剖结构的跟踪三维超声扫描、自动三维超声到超声配准以及使用光学位置传感系统的红外发光二极管（IRED）标记将模拟计算机断层扫描与超声数据配准。对于体模内的四个目标位置，该系统的平均目标定位精度为2.5毫米，而使用传统的激光对准患者定位方法获得的精度为1.6毫米。由于体模是刚性的，这代表了该系统可能达到的最佳设置精度。因此，这些结果表明，基于三维超声的目标定位在实际中是可行的，并且有可能提高在日常器官位移幅度大于1毫米的部位进行放射治疗时患者定位的准确性。
