Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa 52242, USA.
Med Phys. 2010 Mar;37(3):1261-72. doi: 10.1118/1.3312210.
Radiation therapy (RT) for lung cancer is commonly limited to subtherapeutic doses due to unintended toxicity to normal lung tissue. Reducing the frequency of occurrence and magnitude of normal lung function loss may benefit from treatment plans that incorporate the regional lung and radiation dose information. In this article, the authors propose a method that quantitatively measures the regional changes in lung tissue function following a course of radiation therapy by using 4DCT and image registration techniques.
4DCT data sets before and after RT from two subjects are used in this study. Nonlinear 3D image registration is applied to register an image acquired near end inspiration to an image acquired near end expiration to estimate the pulmonary function. The Jacobian of the image registration transformation, indicating local lung expansion or contraction, serves as an index of regional pulmonary function. Approximately 120 annotated vascular bifurcation points are used as landmarks to evaluate registration accuracy. The authors compare regional pulmonary function before and after RT to the planned radiation dose at different locations of the lung.
In all registration pairs, the average landmark distances after registration are on the order of 1 mm. The pulmonary function change as indicated by the Jacobian change ranges from -0.15 to 0.1 in the contralateral lung and -0.22 to 0.23 in the ipsilateral lung for subject A, and ranges from -0.4 to 0.39 in the contralateral lung and -0.25 to 0.5 in the ipsilateral lung for subject B. Both of the subjects show larger range of the increase in the pulmonary function in the ipsilateral lung than the contralateral lung. For lung tissue regions receiving a radiation dose larger than 24 Gy, a decrease in pulmonary function was observed. For regions receiving a radiation dose smaller than 24 Gy, either an increase or a decrease in pulmonary function was observed. The relationship between the pulmonary function change and the radiation dose varies at different locations.
With the use of 4DCT and image registration techniques, the pulmonary function prior to and following a course of radiation therapy can be measured. In the preliminary application of this approach for two subjects, changes in pulmonary function were observed with a weak correlation between the dose and pulmonary function change. In certain sections of the lung, detected locally compromised pulmonary function may have resulted from radiation injury.
由于放射性对正常肺组织的非靶向毒性，肺癌的放射治疗（RT）通常限于亚治疗剂量。通过治疗计划纳入区域性肺和辐射剂量信息，可能会减少正常肺功能丧失的发生频率和程度。在本文中，作者提出了一种通过 4DCT 和图像配准技术定量测量放射治疗后肺组织功能区域性变化的方法。
本研究使用了两名患者的治疗前后的 4DCT 数据集。应用非线性 3D 图像配准将吸气末获取的图像与呼气末获取的图像进行配准，以估计肺功能。图像配准变换的雅可比行列式表示局部肺扩张或收缩，作为区域性肺功能的指标。大约 120 个标注的血管分叉点用作评估配准精度的标志点。作者将治疗前后的区域性肺功能与肺部不同位置的计划放射剂量进行比较。
在所有配准对中，配准后标志点的平均距离约为 1 毫米。雅各布行列式变化所表示的肺功能变化范围在 A 患者的对侧肺中为-0.15 至 0.1，在同侧肺中为-0.22 至 0.23；在 B 患者的对侧肺中为-0.4 至 0.39，在同侧肺中为-0.25 至 0.5。两个患者都显示出同侧肺的肺功能增加范围大于对侧肺。对于接受大于 24Gy 放射剂量的肺组织区域，观察到肺功能下降。对于接受小于 24Gy 放射剂量的区域，观察到肺功能增加或减少。肺功能变化与剂量之间的关系在不同部位有所不同。
使用 4DCT 和图像配准技术，可以测量放射治疗前后的肺功能。在对两名患者的初步应用中，观察到肺功能变化，剂量与肺功能变化之间存在弱相关性。在肺部的某些部位，检测到局部受损的肺功能可能是由于放射性损伤所致。
