A three-dimensional head-and-neck phantom for validation of multimodality deformable image registration for adaptive radiotherapy
A three-dimensional head-and-neck phantom for validation of multimodality deformable image registration for adaptive radiotherapy
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DOI：
10.1118/1.4901523
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发表时间：
2014-12-01
期刊：
影响因子：
3.8
通讯作者：
Pouliot, Jean
中科院分区：
文献类型：
--
作者：
Singhrao, Kamal;Kirby, Neil;Pouliot, Jean
目的：开发一种三维（3D）可变形头颈部（H&N）体模，该体模具有用于千伏（kV）和兆伏（MV）成像模式的真实组织对比度，并使用它来客观地评估可变形图像配准（DESIGN）算法。方法：该体模代表H& N患者解剖结构。它是由热塑性塑料制成的，热塑性塑料在沸水中变得柔韧，环氧树脂硬化。使用添加剂系统，调整这些材料的Hounsfield单位（HU）值，以模拟kV和MV成像的解剖结构。体模沿矢状面中部沿着打开，以显示射线可透标记，用于表征体模变形。对变形和未变形的体模进行kV和MV成像。此外，还创建了校准曲线，以将MV扫描的HU更改为与kV HU（MC）相似。提取的地面实况变形，然后比较两个市售的ARM-A算法的结果，从速度医疗解决方案和MIM software.Results：幻影产生了一个3D变形，代表颈部屈曲，幅度高达8 mm，并能够代表组织HU的kV和MV成像模式。两种测试的变形算法产生了截然不同的结果。对于kV-kV配准，MIM产生的平均误差和最大误差分别为1.8 mm和11.5 mm。Velocity的相同数值分别为2.4和7.1 mm。对于MV-MV，kV-MV和kV-MC Velocity产生相似的平均和最大误差值。然而，MIM，产生了这些情况下的所有三个粗差，最大误差范围从33.4到41.6 mm.Conclusions：在不同的成像方式的应用程序的跨组织HU和成像伪影的存在的差异是特别困难的。出于这个原因，必须为此目的专门验证并行计算算法。所开发的H&N体模是实现这一目的的有效工具。(C)2014年美国医学物理学家协会。
Purpose: To develop a three-dimensional (3D) deformable head-and-neck (H&N) phantom with realistic tissue contrast for both kilovoltage (kV) and megavoltage (MV) imaging modalities and use it to objectively evaluate deformable image registration (DIR) algorithms.Methods: The phantom represents H& N patient anatomy. It is constructed from thermoplastic, which becomes pliable in boiling water, and hardened epoxy resin. Using a system of additives, the Hounsfield unit (HU) values of these materials were tuned to mimic anatomy for both kV and MV imaging. The phantom opens along a sagittal midsection to reveal radiotransparent markers, which were used to characterize the phantom deformation. The deformed and undeformed phantoms were scanned with kV and MV imaging modalities. Additionally, a calibration curve was created to change the HUs of the MV scans to be similar to kV HUs, (MC). The extracted ground-truth deformation was then compared to the results of two commercially available DIR algorithms, from Velocity Medical Solutions and MIM software.Results: The phantom produced a 3D deformation, representing neck flexion, with a magnitude of up to 8 mm and was able to represent tissue HUs for both kV and MV imaging modalities. The two tested deformation algorithms yielded vastly different results. For kV-kV registration, MIM produced mean and maximum errors of 1.8 and 11.5 mm, respectively. These same numbers for Velocity were 2.4 and 7.1 mm, respectively. For MV-MV, kV-MV, and kV-MC Velocity produced similar mean and maximum error values. MIM, however, produced gross errors for all three of these scenarios, with maximum errors ranging from 33.4 to 41.6 mm.Conclusions: The application of DIR across different imaging modalities is particularly difficult, due to differences in tissue HUs and the presence of imaging artifacts. For this reason, DIR algorithms must be validated specifically for this purpose. The developed H&N phantom is an effective tool for this purpose. (C) 2014 American Association of Physicists in Medicine.