Ogawa Koichi, Ichimura Yuta
Department of Applied Informatics, Faculty of Science and Engineering, Hosei University, 3-7-2 Kajinocho, Koganei, Tokyo, 184-8584, Japan,
Ann Nucl Med. 2014 Oct;28(8):716-24. doi: 10.1007/s12149-014-0865-2. Epub 2014 Jun 11.
The aim of the study was to develop a new SPECT system that makes it possible to acquire projection data stationary using a triple-head gamma camera system.
We evaluated several data acquisition geometry with multi-pinhole collimators attached to a triple-head gamma camera system. The number of pinholes for each camera was three to twelve, and we located these holes on collimator plates adequately. These collimator holes were tilted by predefined angles to efficiently cover the field of view of the data acquisition system. Acquired data were reconstructed with the OS-EM method. In the simulations, we used a three-dimensional point source phantom, brain phantom, and myocardial phantom. Attenuation correction was conducted with the x-ray CT image of the corresponding slice.
Reconstructed images of the point source phantom showed that the spatial resolution could be improved with the small number of pinholes. On the other hand, reconstructed images of the brain phantom showed that the large number of pinholes yielded images with less artifact. The results of the simulations with the myocardial phantom showed that more than eight pinholes could yield an accurate distribution of activity when the source was distributed only in the myocardium.
The results of the simulations confirmed that more than eight pinholes for each detector were required to reconstruct an artifact free image in the triple-head SPECT system for imaging of brain and myocardium.
本研究的目的是开发一种新的单光子发射计算机断层扫描（SPECT）系统，该系统能够使用三头γ相机系统获取静止的投影数据。
我们评估了几种将多针孔准直器连接到三头γ相机系统的数据采集几何结构。每个相机的针孔数量为3至12个，我们将这些针孔适当地定位在准直器板上。这些准直器孔以预定义的角度倾斜，以有效覆盖数据采集系统的视野。采集的数据用有序子集期望最大化（OS-EM）方法重建。在模拟中，我们使用了三维点源模型、脑模型和心肌模型。使用相应切片的x射线计算机断层扫描（CT）图像进行衰减校正。
点源模型的重建图像表明，少量针孔可以提高空间分辨率。另一方面，脑模型的重建图像表明，大量针孔产生的图像伪影较少。心肌模型的模拟结果表明，当源仅分布在心肌中时，超过8个针孔可以产生准确的活性分布。
模拟结果证实，在用于脑和心肌成像的三头SPECT系统中，每个探测器需要超过8个针孔才能重建无伪影图像。
