医用超声源输出声强检测仪的研制

【作者】 王冰；

【导师】 陈传岭； 吕运朋；

【作者基本信息】 郑州大学 ， 测试计量技术及仪器， 2007， 硕士

【摘要】 随着医疗和计生事业的不断发展，超声诊断仪已经成为医用临床诊断检查必备的医疗仪器之一。近十几年来，人们使用超声诊断仪器，通过检测和显示人体组织和器官的声学特性来诊断疾病。在人们使用各种超声诊断仪器的同时，超声诊断的安全性问题是个极为重要而未彻底解决的问题，自80年代以来，这个问题尤为引人关注。其背景之一是超声诊断仪在妇产方面的应用日益广泛，致使超声诊断早孕的可能影响问题变得十分敏感；其二是一些超声多普勒成像仪的声输出趋高，其存在的潜伏不安全性令人关注。为此，国家质量技术监督局专门制定和颁布了国家标准和计量检定规程来约束和规范医用超声源的输出声强。本文从超声学的基本内容入手，介绍了超声学领域的基本概念，其中重点介绍了声强和声功率的概念，由于被测量是时间空间的平均声强，依据声强和声功率的对应关系，转换为测量声功率，测量声功率的方法有很多种，本系统采用了经典的辐射力法，这种方法也符合设计之初的目的——便携式、稳定性好、便于现场检测。本系统改进了教科书上的辐射力法，由竖直放置的锥形靶或平面放置的圆形靶改进为竖直放置的圆形靶，靶的类型为全反射靶，在放置靶的水槽内壁上布满了吸声材料，保证了超声束的近似100％作用力。本系统采用了磁电式力平衡侍服检测机制，其原理是由磁电式力平衡机构中的线圈绕组的电流I与动圈所在的恒定磁场相互作用，产生的转动力矩平衡于超声束作用于全反射靶面的辐射压力F产生的力矩，由此得出电流I与声功率P的对应关系，把测力学量转换为测电学量。系统的整体思路是采用声—力—电转换的方法，实现了测量的高精度。在后续的数据处理中，系统采用MC14433型A／D转换芯片实现输出显示，再将这个BCD码形式的数据由RS232串口送至计算机，由检定软件判别声强测量值是否合格，最后出具合格证书或检定结果通知书。更多还原

【Abstract】 Accompany with the continuous development of the medical treatment and family planning, ultrasonic diagnosis already becomes one of the essential medical treatment instruments with the clinic. In the past ten years, people use ultrasonic to diagnose a patient, detect and show the acoustics characteristic of human body’s organization and organ to examine the disease. At the same time of people use various ultrasonic detectors in clinic, the safety problem of ultrasonic detectors becomes very important but doesn’t thoroughly resolve yet. Since 1980’s, this problem is more arrestive. One of its backgrounds is ultrasonic diagnosis expands increasingly in the application of the obstetrics and gynecology, cause the possible influence problem of early pregnancy diagnosis becomes very sensitive; the second is the ultrasonic exportation of some Doppler imaging apparatuses tend to high, is existence of the latent insecurity arouse people’s concern. Therefore, the National Quality and Technology Supervision Administration draw up and promulgate national standards and measurement calibration regulations to restrict and normalize the exportation of the medical ultrasonic source.This text commences from the basic contents of ultrasonic, introduces the basic concept of ultrasonic realm, and emphasis on introducing the definition of acoustic intensity and acoustic power. Because measurand is average acoustic intensity of time and space, according to the relationship of acoustic intensity and acoustic power, the system turns to measure acoustic power. There are many methods for measuring acoustic power, and the system adopts the classic radiometric force method, this kindof method also matches to original purpose-portable type, good stability, andeasy to spot measurement. The system improves the radiometric force method on the textbook, it places the vertical circular target instead of vertical taper target or horizontal circular target, and the type of target is total reflection. The system also spread sound absorbing material inside the water tank all over; make sure the almost total function of ultrasonic. The system adopts the magnetoelectricity type force balance service-detecting method. Its principle is that the current in the electric coil of the balance system interact with stationary magnetic field of moving coil, then a driving moment produced balances with the moment of radiation pressure in ultrasonic beam’s functioning on the total reflection target, as a result, the system can get the relationship of electric current and acoustic power, mechanical parameters’ measurement turns to electricity parameters’ measurement, and the system can adopt some common circuits to carrying out the measurement of electricity parameters. The whole thinking way is a conversion method of Acoustic to Force to Electricity, and then carry out the high accuracy for measurement.In the following data-processing, the system adopts MC14433 type A/D conversion chip for realizing a display, then the system sends the BCD type data code to a computer by RS232 interface, the examination software judges qualified or not automatically, and it can make a qualified certificate or examination result notification finally.更多还原