摘要
Abstract
Objective By analyzing the protective effects of lead screens with different lead equivalents on different types of medical diagnostic X-ray machines,to provide guidance for medical staffand accompanying personnel in choosing appropriate lead screens.Methods The X-ray energy spectrum was simulated by the Monte Carlo method when the tube voltage was 50-140 kV,the total filtration thickness was 0.5-5.0 mm(Al),and the anode angle was 12°.Taking this as the source term,the normalized dose rate and attenuation factor of lead screens after X-ray shielding were simulated,and the actual protective effects of lead screens with different lead equivalents on different X-ray machines were evaluated in combination with experimental measurements.Results The attenuation factor of lead screens increased with the increase of lead equivalent.When it exceeded 1.5 mmPb,the attenuation factor increased significantly.A 1.0 mmPb lead screen could effectively shield the X-rays generated by a 60 kV X-ray machine with a tube voltage.If the distance between the machine head and the lead screen was more than 3 m,a 1.0 mmPb lead screen could reduce the dose rate of the machine head to below 1 µSv/h at a distance of 1 m in any direction.Conclusion The tube voltage of the X-ray machine,the filtration thickness,the lead equivalent of the lead screen and the protective distance are important factors affecting the protective effect of the lead screen.1.0 mmPb lead screen can effectively shield X-ray machines such as dental X-ray machines with tube voltages set below 60 kV.For X-ray machines with tube voltages set below 100 kV,such as digital subtraction angiography(DSA),oral CT,and mobile C-arm,a 2.2 mmPb lead screen can be selected at a distance of 0.5 meters from the machine head and a 2.0 mmPb lead screen at a distance of 1 meter from the machine head,while avoiding the primary radiation.For X-ray machines with tube voltages such as digital radiography(DR)and CT set above 140 kV,distance protection should be given priority consideration.关键词
铅当量/铅屏风/医用诊断X射线机/X射线能谱/归一化X射线剂量率/衰减倍数Key words
lead equivalent/lead screen/medical diagnostic/X-ray machine/X-ray energy spectrum/normalized X-ray dose rate/attenuation factor分类
医药卫生
