IEEE Trans Image Process. 2013 Dec;22(12):5085-95. doi: 10.1109/TIP.2013.2280185. Epub 2013 Aug 30.
The number of projections is a critical factor in tomographic imaging. The larger the number, the better the quality of the reconstructed image; however, it increases the radiation dose delivered to the patient. Therefore, it is important to keep the number of projections as small as possible. Traditionally, the projections are taken by moving the x-ray source around the patient at uniform angular steps. Taking projections at nonuniform steps may result in better images as compared with that obtained using uniform projections. This paper describes two different approaches that adjust the step size to adaptively select the angle of projections. The first one is based on the spectral richness of the acquired projections and the second relies on the amount of new information added by successive projections. The superior performance of the two proposed methods over the uniform projection scheme is demonstrated through simulation results using both phantom and real images.
投影数量是层析成像的一个关键因素。投影数量越多，重建图像的质量越好；然而，它会增加向患者传递的辐射剂量。因此，尽可能减少投影数量非常重要。传统上，通过在患者周围以均匀角度步长移动 X 射线源来获取投影。与使用均匀投影相比，采用非均匀步长的投影可能会获得更好的图像。本文描述了两种不同的方法，这些方法可调整步长以自适应地选择投影角度。第一种方法基于获取的投影的光谱丰富度，第二种方法依赖于连续投影添加的新信息量。通过使用幻影和真实图像进行的模拟结果，证明了这两种方法比均匀投影方案具有更好的性能。
