How does CT image noise affect 3D deformable image registration for image-guided radiotherapy planning?
How does CT image noise affect 3D deformable image registration for image-guided radiotherapy planning?
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DOI：
10.1118/1.2837292
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发表时间：
2008-03-01
期刊：
影响因子：
3.8
通讯作者：
Weiss, Elizabeth
中科院分区：
文献类型：
--
作者：
Murphy, Martin J.;Wei, Zhouping;Weiss, Elizabeth
目的：测量变形图像配准对图像噪声的敏感性。可变形图像配准可用于将器官轮廓和其他治疗计划数据从一个CT映射到另一个CT。这些CT研究可以用传统的扇束CT系统或更新颖的锥束CT技术来获取。然而，锥束CT图像可能具有比扇束CT更高的噪声水平，这可能降低配准精度。我们研究了图像质量差异对扇形束CT和模拟锥束噪声CT的变形配准的影响。方法：我们的研究使用了三个CT检查的五个前列腺患者。每个CT由三位经验丰富的放射肿瘤学家绘制轮廓。对于每例患者，将一个CT指定为源图像，另外两个CT指定为目标图像。使用可变形图像配准过程将每个源CT配准到每个靶CT，然后将手动绘制的治疗计划轮廓从源CT传输到靶CT。通过将自动传输轮廓（以及变形配准过程）与目标CT上的手动轮廓进行比较，评估其准确性，并评价手动轮廓中观察者间变异性的差异。然后修改每个目标CT，以包括锥束CT的增加的噪声特性，并重复测试。通过监测自动传输轮廓的变化来检测由于噪声增加而导致的配准精度的变化。结果如下：我们发现，额外的噪声不会造成配准精度的显着损失的幅度超过了通常会发现在一个实际的锥束CT。总结：我们的结论是，锥束CT的噪声水平，可能会降低手动轮廓的准确性不降低图像配准和自动轮廓的准确性。(C)2008年美国医学物理学家协会。
Purpose: To measure the sensitivity of deformable image registration to image noise. Deformable image registration can be used to map organ contours and other treatment planning data from one CT to another. These CT studies can be acquired with either conventional fan-beam CT systems or more novel cone-beam CT techniques. However, cone-beam CT images can have higher noise levels than fan-beam CT, which might reduce registration accuracy. We have investigated the effect of image quality differences on the deformable registration of fan-beam CTs and CTs with simulated cone-beam noise. Method: Our study used three CT studies for each of five prostate patients. Each CT was contoured by three experienced radiation oncologists. For each patient, one CT was designated the source image and the other two were target images. A deformable image registration process was used to register each source CT to each target CT and then transfer the manually drawn treatment planning contours from the source CT to the target CTs. The accuracy of the automatically transferred contours (and thus of the deformable registration process) was assessed by comparing them to the manual contours on the target CTs, with the differences evaluated with respect to interobserver variability in the manual contours. Then each of the target CTs was modified to include increased noise characteristic of cone-beam CT and the tests were repeated. Changes in registration accuracy due to increased noise were detected by monitoring changes in the automatically transferred contours. Results: We found that the additional noise caused no significant loss of registration accuracy at magnitudes that exceeded what would normally be found in an actual cone-beam CT. Summary: We conclude that noise levels in cone-beam CTs that might reduce manual contouring accuracy do not reduce image registration and automatic contouring accuracy. (C) 2008 American Association of Physicists in Medicine.