Institute for Computational and Engineering Sciences, The University of Texas at Austin, Austin, Texas.
Department of Biomedical Engineering, Wake Forest School of Medicine, Winston-Salem, North Carolina; Comprehensive Cancer Center, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina.
Int J Radiat Oncol Biol Phys. 2018 Apr 1;100(5):1270-1279. doi: 10.1016/j.ijrobp.2017.12.004. Epub 2017 Dec 13.
To develop and investigate a set of biophysical models based on a mechanically coupled reaction-diffusion model of the spatiotemporal evolution of tumor growth after radiation therapy.
Post-radiation therapy response is modeled using a cell death model (M), a reduced proliferation rate model (M), and cell death and reduced proliferation model (M). To evaluate each model, rats (n = 12) with C6 gliomas were imaged with diffusion-weighted magnetic resonance imaging (MRI) and contrast-enhanced MRI at 7 time points over 2 weeks. Rats received either 20 or 40 Gy between the third and fourth imaging time point. Diffusion-weighted MRI was used to estimate tumor cell number within enhancing regions in contrast-enhanced MRI data. Each model was fit to the spatiotemporal evolution of tumor cell number from time point 1 to time point 5 to estimate model parameters. The estimated model parameters were then used to predict tumor growth at the final 2 imaging time points. The model prediction was evaluated by calculating the error in tumor volume estimates, average surface distance, and voxel-based cell number.
For both the rats treated with either 20 or 40 Gy, significantly lower error in tumor volume, average surface distance, and voxel-based cell number was observed for the M and M models compared with the M model. The M model fit, however, had significantly lower sum squared error compared with the M and M models.
The results of this study indicate that for both doses, the M and M models result in accurate predictions of tumor growth, whereas the M model poorly describes response to radiation therapy.
基于肿瘤放射治疗后时空演变的力学耦联反应-扩散模型，开发并研究一套生物物理模型。
采用细胞死亡模型（M）、增殖率降低模型（M）和细胞死亡与增殖率降低模型（M）来模拟放射治疗后的反应。为了评估每个模型，对接受 C6 神经胶质瘤的大鼠在 2 周内的 7 个时间点进行扩散加权磁共振成像（MRI）和对比增强 MRI 扫描。大鼠在第 3 和第 4 次成像时间点之间接受 20 或 40 Gy 的照射。扩散加权 MRI 用于根据对比增强 MRI 数据中增强区域内的肿瘤细胞数量来估计肿瘤细胞数量。将每个模型拟合到时间点 1 到时间点 5 的肿瘤细胞数量的时空演变中，以估计模型参数。然后使用估计的模型参数来预测最后 2 个成像时间点的肿瘤生长情况。通过计算肿瘤体积估计值、平均表面距离和体素细胞数的误差来评估模型预测。
对于接受 20 或 40 Gy 照射的大鼠，M 和 M 模型的肿瘤体积、平均表面距离和体素细胞数的误差明显低于 M 模型。然而，M 模型的拟合具有明显更低的平方和误差，优于 M 和 M 模型。
本研究结果表明，对于两种剂量，M 和 M 模型都能准确预测肿瘤生长，而 M 模型则不能很好地描述放射治疗的反应。
