Karimaghaloo Z, Fichtinger G, Gobbi D G, Burdette E C, Rohling R N, Abolmaesumi P
Department of Electrical & Computer Eng., Queen's University, Kingston, ON, Canada.
Proc IEEE Int Symp Biomed Imaging. 2008 Jun 13;2008:780-783. doi: 10.1109/ISBI.2008.4541112.
In prostate brachytherapy, determining the 3D location of the seeds relative to surrounding structures is necessary for calculating dosimetry. Ultrasound imaging provides the ability to visualize soft tissues, and implanted seeds can be reconstructed from C-arm fluoroscopy. Registration between these two complementary modalities would allow us to make immediate provisions for dosimetric deviation from the optimal implant plan. METHODS: We propose intensity-based registration between ultrasound and a reconstructed model of seeds from fluoroscopy. The ultrasound images are pre-processed with recursive thresholding and phase congruency. Then a 3D ultrasound volume is reconstructed and registered to the implant model using mutual information. RESULTS: A standard training phantom was implanted with 49 seeds. Average registration error between corresponding seeds relative to the ground truth is 0.09 mm. The effect of false positives in ultrasound was investigated by masking seeds from the fluoroscopy reconstructed model. The registration error remained below 0.5 mm at a rate of 30% false positives. CONCLUSION: Our method promises to be clinically adequate, where requirements for registration is 1.5 mm.
在前列腺近距离放射治疗中，确定种子源相对于周围结构的三维位置对于剂量计算是必要的。超声成像能够可视化软组织，并且植入的种子源可以通过C型臂荧光透视重建。这两种互补模态之间的配准将使我们能够立即针对与最佳植入计划的剂量偏差做出调整。方法：我们提出基于强度的超声与荧光透视重建的种子源模型之间的配准。超声图像通过递归阈值处理和相位一致性进行预处理。然后重建三维超声容积，并使用互信息将其与植入模型配准。结果：一个标准训练体模植入了49颗种子源。相对于真实情况，相应种子源之间的平均配准误差为0.09毫米。通过从荧光透视重建模型中屏蔽种子源来研究超声中假阳性的影响。在假阳性率为30%时，配准误差仍低于0.5毫米。结论：我们的方法有望在临床上适用，临床配准要求为1.5毫米。
