常规光源L边荧光CT成像质量影响因素研究

Study on effect factors of image quality of polychromatic L-shell X-ray fluorescence computed tomography

常规光源荧光CT是一种获取元素三维分布的计算机断层扫描成像技术,该技术在癌症的早期诊断中具有重要的潜在应用价值,特别是L边荧光CT.利用蒙特卡洛方法建立了以40kV下银靶的X射线光管原始光谱为入射光源的常规光源L边荧光CT系统.利用内嵌直径2mm铂纳米粒子溶液的直径4mm圆柱模体,探索了单个投影下入射光子数和投影数等因素对于荧光CT成像质量的影响能力.结果表明,单个投影下入射光子数和投影数的增加,均可以提高荧光CT图像的相对噪声比.在总入射光子数一定的情况下,投影数的减少可以有效地提高荧光CT的检测限,这为提高荧光CT系统的探测能力具有重要的意义.

X-ray fluorescence computed tomography （XFCT） is a potential experimental technique to investigate the spatial distribution of low element concentration in sample, which has great potential application in early diagnosis of cancer. In this investigation, polychromatic L shell X-ray fluorescence computed tomography based on X-ray tube was built by Monte Carlo method. A four millimeter in diameter phantom containing a two millimeter in diameter insertion with platinum solutions was used in this investigation. Effect of incident particle number of each projection and projection number on XFCT image quality was investigated. The results indicate that the increase of incident particle number of each projection and projection number can improve the contrast-to noise ratio of XFCT image. When the total number of incident particle was determined, decreasing projection number properly can improve the lowest detectable ability of L-shell X-ray fluorescence computed tomography. It provided a method to improve the detectable ability of polychromatic L-shell X-ray fluorescence computed tomography.