Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, V6T 1Z1, Canada.
Phys Med Biol. 2010 Jan 7;55(1):237-46. doi: 10.1088/0031-9155/55/1/014.
The use of functional imaging in radiotherapy treatment (RT) planning requires accurate co-registration of functional imaging scans to CT scans. We evaluated six methods of image registration for use in SPECT-guided radiotherapy treatment planning. Methods varied in complexity from 3D affine transform based on control points to diffeomorphic demons and level set non-rigid registration. Ten lung cancer patients underwent perfusion SPECT-scans prior to their radiotherapy. CT images from a hybrid SPECT/CT scanner were registered to a planning CT, and then the same transformation was applied to the SPECT images. According to registration evaluation measures computed based on the intensity difference between the registered CT images or based on target registration error, non-rigid registrations provided a higher degree of accuracy than rigid methods. However, due to the irregularities in some of the obtained deformation fields, warping the SPECT using these fields may result in unacceptable changes to the SPECT intensity distribution that would preclude use in RT planning. Moreover, the differences between intensity histograms in the original and registered SPECT image sets were the largest for diffeomorphic demons and level set methods. In conclusion, the use of intensity-based validation measures alone is not sufficient for SPECT/CT registration for RTTP. It was also found that the proper evaluation of image registration requires the use of several accuracy metrics.
在放射治疗 (RT) 计划中使用功能成像需要将功能成像扫描与 CT 扫描进行准确配准。我们评估了六种用于 SPECT 引导的放射治疗计划的图像配准方法。这些方法的复杂程度从基于控制点的 3D 仿射变换到变形恶魔和水平集非刚性配准不等。十名肺癌患者在接受放射治疗前接受了灌注 SPECT 扫描。混合 SPECT/CT 扫描仪的 CT 图像与计划 CT 进行配准，然后将相同的变换应用于 SPECT 图像。根据基于配准 CT 图像的强度差异或基于目标配准误差计算的配准评估指标，非刚性配准比刚性方法提供了更高的准确性。然而，由于某些获得的变形场的不规则性，使用这些场对 SPECT 进行变形可能会导致 SPECT 强度分布发生不可接受的变化，从而排除在 RT 计划中的使用。此外，原始和注册 SPECT 图像集之间的强度直方图差异在变形恶魔和水平集方法中最大。总之，仅使用基于强度的验证措施不足以进行 SPECT/CT 配准以用于 RTTP。还发现，适当的图像配准评估需要使用多个准确性指标。
