Schreibmann Eduard, Chen George T Y, Xing Lei
Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Int J Radiat Oncol Biol Phys. 2006 Apr 1;64(5):1537-50. doi: 10.1016/j.ijrobp.2005.11.018. Epub 2006 Feb 28.
To develop a method for deriving the phase-binned four-dimensional computed tomography (4D CT) image sets through interpolation of the images acquired at some known phases.
Four-dimensional computed tomography data sets for 3 patients were acquired. For each patient, the correlation between inhale and exhale phases was studied and quantified using a BSpline deformable model. Images at an arbitrary phase were deduced by an interpolation of the deformation coefficients. The accuracy of the proposed scheme was assessed by comparing marker trajectories and by checkerboard/difference display of the interpolated and acquired images.
The images at intermediate phases could be derived by an interpolation of the deformation field. An analysis of marker movements indicated that 3 mm accuracy is achievable by the interpolation. The subtraction of image analysis indicated a similar level of success. The proposed technique was useful also for automatically mapping the organ contours in a known phase to other phases, and for designing patient-specific margins in the presence of respiratory motion. Finally, the technique led to a 90% reduction in the acquired data, because in the BSpline model, a lattice of only a few thousand values is sufficient to describe a CT data set of 25 million pixels.
Organ deformation can be well modeled by using a BSpline model. The proposed technique may offer useful means for radiation dose reduction, binning artifacts removal, and disk storage improvement in 4D imaging.
开发一种通过对在某些已知相位采集的图像进行插值来推导相位分箱四维计算机断层扫描（4D CT）图像集的方法。
获取了3名患者的四维计算机断层扫描数据集。对于每位患者，使用B样条可变形模型研究并量化吸气和呼气相位之间的相关性。通过对变形系数进行插值来推导任意相位的图像。通过比较标记轨迹以及对插值图像和采集图像进行棋盘格/差异显示来评估所提出方案的准确性。
中间相位的图像可以通过变形场的插值得到。标记运动分析表明，插值可实现3毫米的精度。图像分析的减法显示出类似的成功水平。所提出的技术还可用于将已知相位的器官轮廓自动映射到其他相位，以及在存在呼吸运动的情况下设计患者特异性边界。最后，该技术使采集的数据减少了90%，因为在B样条模型中，仅几千个值的网格就足以描述2500万像素的CT数据集。
使用B样条模型可以很好地模拟器官变形。所提出的技术可能为4D成像中的辐射剂量降低、分箱伪影去除和磁盘存储改进提供有用的方法。
