X射线线阵列探测器均匀性研究

Study of Uniformity in X-ray Linear Array Detectors

实验测试了芬兰X-SCAN0.4f线阵列探测器在X射线扫描前后的成像均匀性。得出扫描前阵列探测器各单元的本底输出随时间的漂移规律和扫描后各单元对X射线的响应规律。结果发现阵列探测器各单元扫描前后的响应均存在不一致性。通过偏置和增益的校准虽然可以达到各单元响应的一致性,但没有真正解决各单元响应不一致的问题,这对定量计算会产生误差。用蒙特卡罗方法计算了不同厚度GOS闪烁晶体对不同能量入射光子的能量沉积效率和晶体阵列间的串扰,分析了可能引起不均匀性的原因之一的串扰问题。模拟结果给出了阵列单元间的串扰与晶体的尺寸和入射X射线的能量的定量关系,为下一步探测器结构的改进和软件的修正提供了依据。

It shows the outputs of the array detectors both with X-rays and without X-rays.It is found that the outputs uniformity is existed under the two situations before.Although the uniformity could be decreased after the offset calibration and gain calibration,it never touches the real point and will affect the quantitative calculations. EGSnrc package is used to compute energy depositions in different thicknesses crystals with different energy X-rays incident.The reasons that cause Cross-talk between crystals are also discussed.The quantitative relations that will be helpful to the improvement of the array detectors and the software revising are also showed.