X射线硬化对面密度测量灵敏度的影响

Effects of X-ray beam hardening on measurement sensitivity of areal density

利用蒙特卡罗方法分别研究了3种能量X光机的光子穿透不同厚度铝的硬化情况及3种能量光机作为光源测量面密度的过程,并开展了相关实验研究,根据模拟结果对比分析了不同能量光机X射线硬化对面密度测量灵敏度的影响,结果表明:对同种能量光机的光子而言,随着面密度变大,射线硬化程度越严重,导致测量灵敏度下降;光子能量越低,测量灵敏度随面密度变大下降越快,反之亦然;对于某一范围面密度被测物,调整X光机电压使X光子刚好穿透并形成有效图像,可获得最理想的测量灵敏度。

Hardening trends of X-ray beams from three X-ray machines of different energies traversing aluminium plates of different thickness were simulated by means of Monte-Carlo method, as well as the processes of areal density measuring, and cor- responding experimental research was done. The effects of X-ray beams hardening on the measurement sensitivity were analyzed. For the X-ray beams from X-ray machine the same energy, X-ray beams harden more with the areal density increasing, which brings about the reduction of the measurement sensitivity; The lower the energy of photons is , the more quickly the measurement sensitivity reduces, and vice versa. For a certain areal density range, when X-ray photons can just traverse the part of the maxi- mum areal density by adjusting the X-ray tube voltage, the best measurement sensitivity can be obtained.