Characterization of deformation and physical force in uniform low contrast anatomy and its impact on accuracy of deformable image registration
Characterization of deformation and physical force in uniform low contrast anatomy and its impact on accuracy of deformable image registration
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DOI：
10.1118/1.4937935
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发表时间：
2016-01-01
期刊：
影响因子：
3.8
通讯作者：
Hui, Susanta
中科院分区：
文献类型：
--
作者：
Varadhan, Raj;Magome, Taiki;Hui, Susanta
目的：关于力对器官变形的影响及其对精确剂量输送的影响知之甚少。本研究的目的是评估解剖变形及其引起的物理力之间的基本关系，以确定是否存在均匀低对比度解剖结构中的可变形图像配准（restraint）准确性的阈值限制，超过该阈值限制，其适用性可能不适用于临床。为了模拟简化模型，使用粘弹性聚合物开发了具有21个植入基准标记的组织等效可变形膀胱体模。通过施加10 - 70 N增量的力使膀胱体模变形。使用基于强度（MIM）和速度B样条算法进行了研究，通过比较原始目标图像上的21个标记位置的3D矢量与从每个目标图像中获得的标记位置的合成，从cross.Results：施加的力之间的关系在一维变形沿着施加的力的轴和三维变形的体模显示出线性响应。标记的最大和平均位移对施加的力表现出非线性响应。在没有植入标记物的情况下，由于阈值极限仅为20 N（5 mm变形），标记物的平均误差>= 3 mm，因此，MRI性能不佳。对于基于强度（MIM）的算法，仅添加一个标记物，MRI性能显著改善。相比之下，速度B样条算法表现出降低的敏感性，在源和目标images.Conclusions中引入的标记的数量：的限制，适用性的bandwidth是强烈依赖于变形的大小。存在阈值限制，超过该阈值限制，在均匀的低对比度解剖结构中，MRI的准确性失败。超声心动图性能对存在的基准标记数量的敏感性表明，如果超声心动图性能仅使用临床解剖结构中存在的对比度丰富的特征进行评估，则结果可能无法反映均匀低对比度解剖结构中的真实超声心动图性能。(C)2016年美国医学物理学家协会。
Purpose: Little is known about the effect of force on organ deformation and consequently its impact on precision dose delivery. The purpose of this study was to evaluate the fundamental relationship between anatomic deformation and its causative physical force to ascertain if a threshold limit exists for deformable image registration (DIR) accuracy in uniform low contrast anatomy, beyond which its applicability may be clinically inappropriate.Methods: To simulate a simplified model, a tissue equivalent deformable bladder phantom with 21 implanted fiducial markers was developed using a viscoelastic polymer. The bladder phantom was deformed by applying a force in increments from 10 to 70 N. DIR accuracy was studied using intensity based (MIM) and Velocity B-spline algorithms by comparing the 3D vector of the 21 marker locations at the original target image with the synthetically derived marker positions from each target image obtained from DIR.Results: The relationship between applied force in 1D deformation along the axis of applied force and 3D deformation of the phantom showed a linear response. The maximum and average displacements of markers exhibited a nonlinear response to the applied force. In the absence of implanted markers, DIR performance was suboptimal with a threshold limit of only 20 N (5 mm deformation) beyond which the average marker error was >= 3 mm. DIR performance improved significantly with the addition of only one marker for the intensity based (MIM) algorithm. In contrast, the Velocity B-spline algorithm showed reduced sensitivity to the number of markers introduced in both the source and target images.Conclusions: The limits of applicability of DIR are strongly dependent on the magnitude of deformation. There is a threshold limit beyond which the accuracy of DIR fails in uniform low contrast anatomy. The sensitivity of the DIR performance to the number of fiducial markers present indicates that if DIR performance is solely assessed with the contrast rich features present in clinical anatomy, the results may not be reflective of the true DIR performance in uniform low contrast anatomy. (C) 2016 American Association of Physicists in Medicine.