X射线管原始谱和透射谱的测量及应用

Measurement and Application of Original Spectrum and Transmission Spectrum of X-ray Tube

本文基于COMET公司MXR225/22型X射线管,使用高纯锗探测器测量了X射线管大、小焦点几种管电压的X射线原始谱,并测量了小焦点下的初始透射谱,在此基础上测量了X射线穿过几种不同材质(铝、钛、铁和铜)吸收片的透射谱。结果表明:X射线管大、小焦点能谱近似相同,低能端X射线比重较大,原始谱中包含铜、银、钨和铅元素的特征峰;初始透射谱低能端硬化明显,并随着管电压升高,高能端所占比重增大,钨特征峰变得明显,X射线平均能量升高,能谱的X射线强度最大区域在最高能量的1/3附近;金属吸收片对X射线硬化明显,硬化效果强烈依赖于其原子序数。相关结果已在工业CT硬化校正中应用,重建图像质量得到改善。

Based on a COMET MXR225/22X-ray tube,in two cases of big and small focuses,the original spectra were measured at different X-ray tube voltages by a HPGe detector.At the same time,the initial transmission spectra were measured under small focus.On this basis,the transmission spectra of X-ray through several different materials（Al,Ti,Fe and Cu）were measured.The results show that the spectra of big and small focuses can be approximately same,the low energy side has a large proportion,and the characteristic peaks of copper,silver,tungsten and lead are showed in original spectrum.The low energy side of the initial transmission spectrum hardens obviously,and the proportion of the high energy side increases with X-ray tube voltage.The characteristic peak of tungsten becomes evident,the X-ray average energy increases,and themaximum intensity area of the spectrum is near the 1/3of the highest energy.The metal absorption sheet hardens X-ray evidently,and the hardening effect strongly depends on its atomic number.The results are applied to the hardening correction of industrial CT,and the quality of the reconstructed image is improved.