摘要
:10 9CdKXRF骨铅体内测量系统对体重指数大的对象测量所得的结果误差较大。测量时胫骨在探测器前的位置对测量结果误差的影响很大。采用模拟体重指数大的被测对象的大体模 ,与原来的标准体模在探测器前不同距离时进行测量的对比分析表明 ,体重指数大的被测对象因其胫骨周围组织层较厚 ,造成康普顿计数大量增加。若胫骨与探测器的距离太近 ,仪器不能正常工作 ,致使X能谱图谱形畸变 ,得到不正确的结果。因此 ,在测量时 ,应保持胫骨在探测器前的距离为2 5mm ,同时 ,应注意相干散射峰的峰位变化 ,保持仪器即时显示的死时间为 3 0 %左右 。
The accuracy of results obtained from the 109 Cd K XRF in vivo measurement system of bone lead for the subjects with high body mass index(BMI)was poor.The main factor affecting the accuracy was the distance between the tibia and the detector.Compared with the standard phantom,a bigger phantom was used to simulate the subject with high BMI in the measurements at the different distances before the detector.The counts of Compton scattering increased highly because of the thicker tissue layer around the tibia of the subjects with high BMI.When the distance between the tibia and the detector was too small,the instrument would provide the distorted X-ray energy spectrums,so that the obtained data were inaccurate.In order to ensure the good measurement precision and accuracy,during the counting period,the distance between the tibia and the detector should be maintained at 25 mm.Besides,the shift of the coherent scattering peak location should be avoided,and the dead time displayed instantly on the instrument should be around 30%.
出处
《广东微量元素科学》
CAS
2001年第9期63-66,共4页
Trace Elements Science
