一种从衰减数据重建X射线球管光谱的方法

Reconstruction of X-Ray Tube Spectra from Attenuation Data

为了获得完整的球管光谱信息以实现X射线的曝光剂量控制和成像质量评估,提出了一个基于模型的光谱重建方法.根据不同厚度的衰减数据,用非线性最小二乘法估计出模型参数值,重建出应用于乳腺X射线检查的球管光谱.相对于传统的光谱重建方法,该方法采用模型约束,有效地遏制了衰减数据中测量噪声的影响,重建的光谱具有较高的精度.实验表明,当衰减数据含有标准差为1%的泊松噪声时,钨靶在35 kV和45 kV球管电压下,重建光谱的误差分别为4.03%和2.92%;钼靶在20 kV和30 kV电压下,误差分别为6.68%和8.41%.

In order to obtain the perfect information of tube spectra so as to control X-ray radiation dose and evaluate image quality, a method for spectral reconstruction in mammography was presented based on a physical model, in which the parameters of the model were estimated through a nonlinear least-square method using attenuation data with different thickness, and then the tube spectra applied to the mammography was reconstructed. In contrast with the conventional methods, the proposed reconstruction is constrained by the spectral model and the influence of measurement errors from attenuation data is effectively restrained. Experimental results show that when attenuation data contains Poisson noise with 1% standard error, for tungsten anode with tube voltage 35 kV and 45 kV the error of the reconstruction is 4.03% and 2. 92% respectively; for molybdenum anode with tube voltage 20 kV and 30 kV the error is 6.68% and 8.41% respectively.