Radiation Medicine Program, Princess Margaret Hospital, 610 University Ave, Toronto, ON M5G 2M9, Canada.
Phys Med Biol. 2012 Oct 21;57(20):6601-14. doi: 10.1088/0031-9155/57/20/6601. Epub 2012 Sep 25.
We have developed a method to register and display 3D parametric data, in particular radiation dose, on two-dimensional endoscopic images. This registration of radiation dose to endoscopic or optical imaging may be valuable in assessment of normal tissue response to radiation, and visualization of radiated tissues in patients receiving post-radiation surgery. Electromagnetic sensors embedded in a flexible endoscope were used to track the position and orientation of the endoscope allowing registration of 2D endoscopic images to CT volumetric images and radiation doses planned with respect to these images. A surface was rendered from the CT image based on the air/tissue threshold, creating a virtual endoscopic view analogous to the real endoscopic view. Radiation dose at the surface or at known depth below the surface was assigned to each segment of the virtual surface. Dose could be displayed as either a colorwash on this surface or surface isodose lines. By assigning transparency levels to each surface segment based on dose or isoline location, the virtual dose display was overlaid onto the real endoscope image. Spatial accuracy of the dose display was tested using a cylindrical phantom with a treatment plan created for the phantom that matched dose levels with grid lines on the phantom surface. The accuracy of the dose display in these phantoms was 0.8-0.99 mm. To demonstrate clinical feasibility of this approach, the dose display was also tested on clinical data of a patient with laryngeal cancer treated with radiation therapy, with estimated display accuracy of ∼2-3 mm. The utility of the dose display for registration of radiation dose information to the surgical field was further demonstrated in a mock sarcoma case using a leg phantom. With direct overlay of radiation dose on endoscopic imaging, tissue toxicities and tumor response in endoluminal organs can be directly correlated with the actual tissue dose, offering a more nuanced assessment of normal tissue toxicities following radiation therapy and accurate registration of radiation dose to the surgical field.
我们开发了一种将三维参数数据（尤其是辐射剂量）注册并显示在二维内窥镜图像上的方法。这种将辐射剂量与内窥镜或光学成像进行配准的方法可能对于评估正常组织对辐射的反应以及在接受放疗后手术的患者中显示受辐射组织具有重要价值。在柔性内窥镜中嵌入电磁传感器来跟踪内窥镜的位置和方向，从而将二维内窥镜图像与 CT 容积图像和相对于这些图像计划的辐射剂量进行配准。基于空气/组织阈值从 CT 图像渲染表面，创建类似于真实内窥镜视图的虚拟内窥镜视图。将辐射剂量分配给虚拟表面的每个部分或已知的表面下的特定深度。剂量可以作为表面上的颜色洗出或表面等剂量线显示。根据剂量或等剂量线位置为每个表面部分分配透明度级别，将虚拟剂量显示叠加到真实内窥镜图像上。使用带有针对该幻影创建的治疗计划的圆柱形幻影来测试剂量显示的空间准确性，该治疗计划与幻影表面上的网格线匹配剂量水平。在这些幻影中，剂量显示的准确性为 0.8-0.99 毫米。为了证明这种方法的临床可行性，还使用患有喉癌并接受放射治疗的患者的临床数据对剂量显示进行了测试，估计显示精度约为 2-3 毫米。通过将辐射剂量直接叠加在内窥镜成像上，腔内器官的组织毒性和肿瘤反应可以直接与实际组织剂量相关联，从而提供对放射治疗后正常组织毒性的更细致评估，并准确地将辐射剂量注册到手术区域。
