Malusek Alexandr, Seger Maria Magnusson, Sandborg Michael, Alm Carlsson Gudrun
Department of Radiation Physics, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden.
Radiat Prot Dosimetry. 2005;114(1-3):337-40. doi: 10.1093/rpd/nch541.
The effect of scatter on reconstructed image quality in cone beam computed tomography was investigated and a function which can be used in scatter-reduction optimisation tasks was tested. Projections were calculated using the Monte Carlo method in an axially symmetric cone beam geometry consisting of a point source, water phantom and a single row of detector elements. Image reconstruction was performed using the filtered backprojection method. Image quality was assessed by the L2-norm-based difference relative to a reference image derived from (1) weighted linear attenuation coefficients and (2) projections by primary photons. It was found that the former function was strongly affected by the beam hardening artefact and did not properly reflect the amount of scatter but the latter function increased with increasing beam width, was higher for the larger phantom and exhibited properties which made it a good candidate for scatter-reduction optimisation tasks using polyenergetic beams.
研究了散射对锥束计算机断层扫描中重建图像质量的影响，并测试了一种可用于散射减少优化任务的函数。在由点源、水体模和单排探测器元件组成的轴对称锥束几何结构中，使用蒙特卡罗方法计算投影。使用滤波反投影法进行图像重建。通过相对于从（1）加权线性衰减系数和（2）一次光子投影得到的参考图像的基于L2范数的差异来评估图像质量。发现前一种函数受束硬化伪影的强烈影响，不能正确反映散射量，但后一种函数随束宽增加而增加，对于较大的体模更高，并且表现出使其成为使用多能束进行散射减少优化任务的良好候选者的特性。
