诊断X射线空气比释动能的绝对测量研究

发布时间：2018-03-10 05:32

本文选题：空气比释动能　切入点：自由空气电离室　出处：《成都理工大学》2013年硕士论文　论文类型：学位论文

【摘要】：x射线诊断学和放射治疗学等电离辐射医学应用蓬勃发展并不断广泛普及,在多种疾病和临床诊断的现代医学是不可或缺的,接受医疗照射的人员不断增加,医学诊断x射线的广泛使用使之成为公众照射剂量的最大的人工电离辐射来源,约占了人工辐射源照射的99%。常规诊断X射线管电压范围从(40-150)kV,射线辐射设备和计量器具至今没有形成完整的溯源体系。为统一x射线剂量量值,保证x射线工作计量器具的准确一致和正确使用,确保人身的安全,必须实现X射线剂量的量值溯源,保证x射线设备的质量控制。论文依托中国计量科学研究院电离辐射所和中国测试技术研究院共同申请的国家科技支撑计划课题《医用X诊断设备计量标准及溯源体系研究》,在现有的中能X射线(60～250)kV空气比释动能基准和低能X射线(10～50)kV空气比释动能基准和基准装置基础上,进行了诊断X射线(40～150)kV空气比释动能绝对测量研究,并复现了空气比释动能的量值,为规范诊断水平空气比释动能的量值传递提供支持。在国内计量单位内首次搭建了介入式管电压测量系统,实现工业X射线管电压的精确测量,并与非介入式管电压测量仪器相互比较,为解决非介入式管电压溯源提供保障；论文初步完成了使用高能量分辨率的能谱仪测量诊断x射线束的能谱测量及分析,使用能谱终点法实现对X射线管电压进行了尝试性的测量。论文对x射线参考辐射束规范的快速建立方法进行研究,在他人的基础上,提出了快速获得半值层和调整辐射质的数值处理方法,建立了国际电工委员会推荐的诊断X射线参考辐射束规范——RQR和RQA系列辐射质规范；通过实验方法研究,对X射线光管的固有过滤等效铝进行了测量。X射线过滤束的能谱可以应用于确定过滤X射线辐射质、X射线机的管电压、自由空气电离室修正因子、空气比释动能到剂量当量的转换系数等,这对于国际比对、量值传递和仪器仪表的检定与校准有着非常重要的推广价值。文章初步实现对X射线过滤束的能谱测量及分析。论文对自由空气电离室的原理和国际上主要国家的基准电离室研究状况进行了调研,在此基础上,设计了实验,实验和计算出复现量值所需要的修正因子,实现了自由空气电离室空气减弱修正系数、复合损失修正系数、电场畸变修正系数、通过室壁的辐射穿透修正系数、光阑边缘穿透修正、极性修正的测量。最后复现了诊断水平X射线的空气比释动能,并合理评估了测量结果的不确定度。在建立的IEC推荐的辐射质下,实现了空气比释动能的量值复现,其不确定度为0.28%(k=1)。
[Abstract]:The application of ionizing radiation medicine, such as x-ray diagnostics and radiotherapy, has flourished and has been widely spread. Modern medicine is indispensable in a wide range of diseases and clinical diagnostics, and the number of people receiving medical radiation is increasing, The widespread use of medical diagnostic x-rays makes them the largest source of artificial ionizing radiation for public exposure, The conventional diagnostic X-ray tube voltage ranges from 40 to 150 kV, and no complete traceability system has been formed for radiation equipment and measuring instruments. To ensure the accurate, consistent and correct use of x-ray working measuring instruments and to ensure the safety of human beings, it is necessary to trace the value of X-ray dose to the source and ensure the quality control of X-ray equipment. The thesis relies on the National Science and Technology support Program Project "Research on Measurement Standards and traceability system of Medical X Diagnostic equipment", which is jointly applied by the Institute of Ionizing radiation of the China Institute of Metrology and the China Institute of Test Technology. On the basis of X ray 60,250kV air specific kinetic energy reference and low energy X ray 1050kV air specific release kinetic energy reference and reference device, In this paper, the absolute measurement of the air specific release kinetic energy of the diagnostic X-ray is studied, and the value of the air specific release kinetic energy is recounted, which provides the support for the standard diagnosis of the horizontal air specific release kinetic energy transfer. The interventional tube voltage measurement system has been set up in the domestic measurement unit for the first time to realize the accurate measurement of the industrial X-ray tube voltage and to compare with the non-interventional tube voltage measurement instrument to provide the guarantee for solving the non-interventional tube voltage traceability. In this paper, the energy spectrum measurement and analysis of diagnostic x-ray beam using high energy resolution energy spectrometer are preliminarily completed. In this paper, the method of rapid establishment of X-ray reference beam specification is studied, based on others, the X-ray tube voltage is measured by using the energy spectrum end point method. In this paper, a numerical treatment method for quickly obtaining half-value layer and adjusting radiation quality is proposed, and the diagnostic X-ray reference beam specification, RQR and RQA series radiative quality code, recommended by the International Electrotechnical Commission, is established. The energy spectrum of X ray filter beam can be used to determine the tube voltage of X ray radiator and the correction factor of free air ionization chamber. The conversion coefficient from air specific release kinetic energy to dose equivalent is very important for international comparison, quantity transfer and verification and calibration of instruments and instruments. The energy spectrum measurement and analysis of X ray filter beams are preliminarily realized in this paper. In this paper, the principle of free air ionization chamber and the research status of reference ionization chamber in major countries are investigated. On this basis, experiments are designed, and the correction factors needed to calculate the reappearance value are designed. The correction coefficients of air attenuation, compound loss and electric field distortion in the free air ionization chamber are realized. The correction coefficients of radiation penetration of the wall of the chamber and the edge of the diaphragm are corrected. The measurement of polarity correction. Finally, the air specific release kinetic energy of diagnostic level X ray is reappeared, and the uncertainty of the measurement result is reasonably evaluated. Under the radiation quality recommended by IEC, the value of air specific release kinetic energy is restated. The uncertainty is 0.28%.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R144

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