Department of Nuclear Medicine, State University of New York at Buffalo, Buffalo, NY, USA.
Phys Med Biol. 2013 Apr 7;58(7):2011-25. doi: 10.1088/0031-9155/58/7/2011. Epub 2013 Mar 4.
We developed SPECT imaging capability on an animal PET scanner to provide a cost effective option for animal SPECT imaging. The SPECT add-on sub-system was enabled by mechanically integrating a multiple-pinhole collimator in the PET detector ring. This study introduces a method to calibrate the geometrical parameters of the SPECT add-on using the PET imaging capability of the scanner. The proposed PET imaging-based calibration method consists of two steps: (1) paint the pinhole apertures of the collimator with a positron emitting radioactive solution; and (2) image the collimator inside the scanner in PET mode. The geometrical parameters of the multi-pinhole SPECT add-on can then be derived directly from a set of PET images by simple linear calculation and used in defining the SPECT system. The method was compared to our implementation of a SPECT calibration approach with model-based fitting of SPECT projection data. The procedure for carrying out the PET imaging-based calibration method is simpler and faster than that of our implementation of the SPECT model-based calibration method. Since it does not require model fitting, the uniqueness of the calibration result is warranted. Better quality SPECT images were reconstructed using the PET-derived calibration parameters rather than our implementation of the SPECT model-based calibration parameters. We conclude that the proposed PET imaging-based calibration method provides a highly effective means for enabling SPECT imaging on a PET scanner.
我们在动物 PET 扫描仪上开发了 SPECT 成像功能，为动物 SPECT 成像提供了一种具有成本效益的选择。SPECT 附加子系统通过在 PET 探测器环中机械集成多针孔准直器来实现。本研究介绍了一种使用扫描仪的 PET 成像能力来校准 SPECT 附加子系统的几何参数的方法。所提出的基于 PET 成像的校准方法包括两个步骤：(1) 用正电子发射放射性溶液涂覆准直器的针孔；(2) 在 PET 模式下对扫描仪内部的准直器进行成像。然后可以通过简单的线性计算直接从一组 PET 图像中得出多针孔 SPECT 附加子系统的几何参数，并用于定义 SPECT 系统。该方法与我们基于模型的 SPECT 投影数据拟合的 SPECT 校准方法进行了比较。与我们的 SPECT 基于模型的校准方法的实施相比，执行基于 PET 成像的校准方法的过程更简单、更快。由于它不需要模型拟合，因此可以保证校准结果的唯一性。使用从 PET 中得出的校准参数重建了质量更好的 SPECT 图像，而不是使用我们的 SPECT 基于模型的校准参数。我们得出结论，所提出的基于 PET 成像的校准方法为在 PET 扫描仪上实现 SPECT 成像提供了一种非常有效的手段。
