A buoyancy method for the measurement of total ultrasound power generated by HIFU transducers

Total acoustic output power is a key parameter for most ultrasonic medical equipment and especially for high intensity focused ultrasound (HIFU) systems, which treat certain cancers and other conditions by the noninvasive thermal ablation of the affected tissue. In planar unfocused fields, the use of a radiation force balance has been considered the most accurate method of measuring ultrasound power. However, radiation force is not strictly dependent on the ultrasound power but, rather, on the wave momentum resolved in one direction. Consequently, measurements based on radiation force become progressively less accurate as the ultrasound wave deviates further from a true plane-wave. HIFU transducers can be very strongly focused with F-numbers less than one: under these conditions, the uncertainty associated with use of the radiation force method becomes very significant. In this article, a new method for determining power is described in detail. Instead of radiation force, the new method relies on measuring the change in buoyancy caused by thermal expansion of castor oil inside a target suspended in a water bath. The change in volume is proportional to the incident energy and is independent of focusing or the angle of incidence of the ultrasound. The principles and theory behind the new method are laid out and the characteristics and construction of an appropriate target are examined and the results of validation tests are presented. The uncertainties of the method are calculated to be approximately +/-3.4% in the current implementation, with the potential to reduce these further. The new technique has several important advantages over the radiation force method and offers the potential to be an alternative primary standard method.     

Advances in ultrasound biomicroscopy

The visualisation of living tissues at microscopic resolution is attracting attention in several fields. In medicine, the goals are to image healthy and diseased tissue with the aim of providing information previously only available from biopsy samples. In basic biology, the goal may be to image biological models of human disease or to conduct longitudinal studies of small-animal development. High-frequency ultrasonic imaging (ultrasound biomicroscopy) offers unique advantages for these applications. In this paper, the development of ultrasound biomicroscopy is reviewed. Aspects of transducer development, systems design and tissue properties are presented to provide a foundation for medical and biological applications. The majority of applications appear to be developing in the 40-60-MHz frequency range, where resolution on the order of 50 microm can be achieved. Doppler processing in this frequency range is beginning to emerge and some examples of current achievements will be highlighted. The current state of the art is reviewed for medical applications in ophthalmology, intravascular ultrasound, dermatology, and cartilage imaging. Ultrasound biomicroscopic studies of mouse embryonic development and tumour biology are presented. Speculation on the continuing evolution of ultrasound biomicroscopy will be discussed.     

The American Institute of Ultrasound Policy and statement on safety

While no simple, absolute answers exist to the question of the safety of diagnostic ultrasound, the available information suggests the following reasonable attitudes towards its medical use.Diagnostic ultrasound has proven to be a valuable tool in medical practice and should be used without hesitation, with appropriate equipment and procedures, when medical benefit is expected. An excellent safety record exists in that after decades of clinical use there is no known instance of human injury due to diagnostic ultrasound.     

Donation and training of medical personnel in compact ultrasound in low-resource settings: how we do it

The authors offer a concise summary of dos and don'ts for the radiologist/sonologist wishing to expand his horizons and join those physicians donating ultrasound equipment and training medical personnel in low-resource countries. Topics include choosing a site, obtaining ultrasound equipment, preparing to travel, and starting a training program. The most important points to keep in mind are: (1) be prepared for any circumstance; (2) do your homework ahead of time; (3) make sure there is a local group "on the ground" that can ensure the machine's sustainability; and (4) allow for much more time to get things accomplished than in the developed world.     

Potential of microsystems in medicine

Summary

In numerous fields of medicine and in particular in minimally invasive therapy, functionality of the existing medico-technical equipment can be improved considerably by increasing use of microstructures or microsystem components. Furthermore, completely new medical instruments (endosystems) are feasible on the basis of microsystem fabrication technologies. With the LIGA technique and mechanical microengineering two novel technologies for medical technology shall be presented. The advantages and opportunities offered by microstructure and microsystems technology shall be illustrated by the examples of microshaped X-ray intensifying screens, micro host structures for cell cultures, microvalve systems for catheter systems and a novel endoscopic operation system for neurosurgery.     

Compact Ultrasound for Improving Maternal and Perinatal Care in Low‐Resource Settings

Objective. Ultrasound imaging, a front‐line diagnostic tool for perinatal care, is rarely available in the developing world, where maternal and newborn mortality rates are starkly higher than elsewhere. The development of portable and inexpensive medical ultrasound machines (compact ultrasound) offers the possibility of broader use of ultrasound. Our objective was to assess the potential benefits and challenges of deploying compact ultrasound in developing countries for improving obstetric health. Methods. Existing literature on perinatal care, compact ultrasound, and issues in the deployments of medical technology in low‐resource settings was reviewed. Anecdotal evidence was assessed, and the authors' field experiences in Nicaragua and Mali were evaluated as a template for wider deployments. Results. Few published studies directly concerned with compact ultrasound in low‐resource settings were found. These, however, in combination with available anecdotal data, support the view that compact ultrasound in less‐developed regions is feasible and would result in a relatively low‐cost improvement in perinatal care. Conclusions. The development of lightweight, portable, and relatively inexpensive ultrasound systems offers a great opportunity for reducing maternal and neonatal mortality in low‐resource settings. Evidence‐based analysis of compact ultrasound deployments as a public‐health response to obstetric needs in less‐developed countries has been hampered by limited data in 3 key areas: maternal and perinatal mortality and morbidity in these settings, evaluations of compact ultrasound systems as reliable alternatives to full‐sized systems, and the lack of outcomes data based on actual deployments of compact ultrasound for this purpose. Field trials of compact ultrasound on a scale commensurate with public health interventions should be undertaken.     

Medical Student Ultrasound Education: A WFUMB Position Paper,Part I

The introduction of ultrasound into medical student education is well underway in many locations around the world, but is still in its infancy or has yet to begin in others. Proper incorporation of ultrasound education into medical training requires planning and resources, both capital and human. In this article, we discuss the state of the art of ultrasound in medical education throughout the world, as well as various methodologies utilized to improve student education and to incorporate ultrasound into every facet of training. Experiences from various educational systems and available evidence regarding the impact of ultrasound education are summarized. Representing multiple societies and specialties throughout the world, we discuss established modern as well as novel education structures and different successful approaches.     

医学超声Doppler技术中位置－速度的检测约束和血流（横向）速度剖面的获得

本文提出了医学超声Ｄｏｐｐｌｅｒ技术中位置和速度检测的约束问题，并从几个方面分析了产生这种约束的原因。作为应用和进一步的理解，文中还介绍了一种避免位置和速度约束关系的血流（横向）速度剖面的估计方法，最后对医学超声多普勒技术中位置和速度的检测约束及血流速度剖面的获得进行了讨论。     

Ultrasound guidance of laser atherectomy

Intravascular ultrasound imaging catheters and forward firing laser atherectomy systems are both being used in the coronary vascular tree of man. When used in conjunction, ultrasound imaging may reduce the probability of perforation and dissection related to laser atherectomy. A novel system is presented which combines ultrasound imaging and laser atherectomy capabilities on the same catheter. The system incorporates a holmium YAG laser directed perpendicular to the long axis of the catheter along with a co-directional ultrasound sensor. Ultrasound images are assembled by computer using the angle of the catheter tip and its linear advance associated with each ultrasound echo signal.In vivo experimental results are presented.     

Ultrasound anatomy of the normal male reproductive tract

Ultrasound is being used with increasing frequency in the evaluation of the male reproductive tract. To detect abnormalities, it is important to have a comprehensive understanding of the normal anatomy and normal variations. In this article, the ultrasound anatomy of the scrotum, penis, prostate, and seminal vesicles is presented. Because ultrasound is a very visual process, the anatomy is presented not only with text, but also through the liberal use of ultrasound images and associated diagrams. Ultrasound is both an operator- and equipment-dependent procedure and, where appropriate, we have included technical discussions regarding ultrasound equipment and settings. © 1996 John Wiley & Sons, Inc.     

Performance testing of medical echo/Doppler equipment.

This paper describes the methods applied in a software package developed by the authors for use in a performance testing protocol for medical ultrasound equipment. The history of performance testing of medical ultrasound equipment is briefly reviewed. This paper is confined to the testing of performance of usage aspects, i.e. imaging performance and Doppler velocity estimation performance. Simple test objects are used which have a long life expectancy. The tests performed both in fundamental and in (tissue) harmonic modes when applicable are spatial resolution, contrast sensitivity, and clutter. The concept of a computational observer is used to define the lesion signal-to-noise ratio and the tissue-to-clutter ratio. Further imaging performance features are penetration depth, slice thickness and geometric conformity of display. Pulsed Doppler velocity measurement features tested are: sensitivity, depth and 3D size of the sample volume, velocity measurement, channel separation. The whole performance measurement protocol as well as the quantitative measurements in the digitized images are implemented in software, together with the graphs and data obtained from the measurements.     

超声分子显像与治疗及设备的研究

近年来,随着医学影像技术的发展,超声分子成像成为当前医学影像学研究的热点之一,其中超声分子探针的设计是分子成像研究的重点和先决条件。靶向超声微泡(球)造影剂在超声分子显像及治疗中的研究和应用愈来愈受到人们的关注,而多学科的融合使其具有更大的发展空间。将超声分子成像设备、超声微泡(球)触发装置、超声分子成像监控与超声分子探针有机结合的"低功率超声分子显像与治疗系统",有望实现超声分子显像及精细、适形、高效的药物体内定位递送、定量控释和疗效评价一体化,为疾病的超声分子显像诊断与治疗提供创新的、适合多学科使用的新技术和科研平台。     

超声图像预处理方法的改进研究

目的在对超声图像传统预处理方法进行处理后效果对比分析的基础上,提出一些改进措施。方法以超声医学影像为关键点,分析其噪声,提取噪声特征,从空间域处理技术来阐述超声医学影像的预处理方法。结果生物医学图像预处理技术是医学图像系统中最关键的技术之一,直接影响医生的正确诊断,以及后期的医学数据分析。对原始图像经过双精度处理,图像整体亮度会被拉低。变换图像窗口,选择感兴趣的灰度区域进行灰度提升,增强图像的灰度可视信息,对比未做双精度处理前的实验。结论采用新的灰度处理方法后的图像,具有平滑的边缘,清晰的细节,能更好地保留细节信息,具有一定的现实意义和实用价值。     

Ultrasound Phantom Using Sodium Alginate as a Gelling Agent

For medical workers, ultrasound phantoms for human soft tissue are used not only for accuracy management of ultrasound diagnosis but also to aid ultrasound‐guided needle and blind catheter insertion training without risk to real patients. For the phantoms, ultrasound characteristics and a texture are required to mimic the human soft tissue. The proposed phantom was composed of sodium alginate, calcium sulfate dihydrate, trisodium phosphate 12‐hydrate, glycerol, and water. The propagation speed, attenuation coefficient, acoustic impedance, and texture of the proposed phantom were almost the same as those of human soft tissue. Expensive chemicals and special equipment are not required.     

基于DICOM标准的超声图像归档与通讯系统的研制与初步应用

目的 开发超声图像归档与通讯系统(PACS)，实现超声成像设备的网络化，解决超声图像的存储和诊断报告书写的计算机化、标准化。方法 利用C 计算机语言开发超声图像工作站，获取、显示、处理和打印超声动静态图像，将科室内10台超声设备连接成医学数字影像传输(DICOM)网络；中心图像服务器和超声科信息管理系统服务器与各图像工作站组成计算机以太网，构成超声PACS；再通过交换机与医院Internet WWW服务器连接，实现超声彩色图文报告的院内发布。结果 成功实现了DICOM数字图像和高质量视频图像的获取、显示、处理和网络传送，与医院信息系统无缝连接，图像的中心存储，诊断报告书写计算机化以及共享打印等功能。结论 超声图像管理系统的应用提高了工作效率及管理水平，推动了医生工作模式的变革，方便了工作、科研和教学，提高了医疗服务层次。规范化、计算机化的诊断报告质量优于人工书写报告。     

AIUM Practice Guideline for the Performance of Ultrasound Examinations of the Head and Neck

The American Institute of Ultrasound in Medicine (AIUM) is a multidisciplinary association dedicated to advancing the safe and effective use of ultrasound in medicine through professional and public education, research, development of guidelines, and accreditation. To promote this mission, the AIUM is pleased to publish, in conjunction with the American Academy of Otolaryngology–Head and Neck Surgery, this revised AIUM Practice Guideline for the Performance of Ultrasound Examinations of the Head and Neck. We are indebted to the many volunteers who contributed their time, knowledge, and energy to bringing this document to completion. The AIUM represents the entire range of clinical and basic science interests in medical diagnostic ultrasound, and, with hundreds of volunteers, the AIUM has promoted the safe and effective use of ultrasound in clinical medicine for more than 50 years. This document and others like it will continue to advance this mission. Practice guidelines of the AIUM are intended to provide the medical ultrasound community with guidelines for the performance and recording of high‐quality ultrasound examinations. The guidelines reflect what the AIUM considers the minimum criteria for a complete examination in each area but are not intended to establish a legal standard of care. AIUM‐accredited practices are expected to generally follow the guidelines with recognition that deviations from these guidelines will be needed in some cases, depending on patient needs and available equipment. Practices are encouraged to go beyond the guidelines to provide additional service and information as needed.     

The prudent use of diagnostic ultrasound

Progress in diagnostic ultrasound is driven by the development of new technology. The place of new techniques in diagnostic algorithms has to be determined jointly by radiologists and clinicians and appropriate arrangements have to be made for training. About pounds 30 million per year is currently spent on diagnostic ultrasound in the UK. Diagnostic ultrasound depends on the information obtained as a result of ultrasonic irradiation of the patient. Biological effects, some of which are undesirable, can be produced by ultrasound but there is no evidence that the exposures used in diagnosis carry any risk. In judging whether ultrasonic scanning is appropriate in any particular situation, it is necessary to consider benefits, costs and available resources. The costs include not only the costs of the test but also the cost of any hypothetical ultrasonic hazard and the cost of misdiagnosis. The most prudent use of ultrasound is that which maximises the benefit-total-cost ratio and although this cannot presently be quantified, some of the concepts involved can be understood in terms of the health increment and the health decrement the latter apparently being equal to zero when the diagnosis is correctly made using contemporary equipment. This approach can be extended to introduce the idea of profit arising from the test. As an example, obstetric ultrasound is considered to be appropriate when there is a medical indication for it. Although routine scanning at 16 weeks of pregnancy has been shown to result in a very large profit, there is still conflicting guidance about its advisability on the grounds of safety and existing accounting systems may restrict access to the profit. In discussing the desirability of ultrasonic scanning, patients can be informed that there is no reason to believe that there are any risks related to ultrasonic exposure. The imminent availability of inexpensive ultrasonic scanners for the layman is a worrying prospect to which the medical profession should now try to develop a prudent response.     

AIUM Standard for Documentation of an Ultrasound Examination

The American Institute of Ultrasound in Medicine (AIUM) is an educational, scientific, and professional society concerned with the advancement of the art and science of ultrasound in medicine and research. To promote this mission, the AIUM is pleased to publish the Standard for Documentation of an Ultrasound Examination. We are indebted to the many volunteers who contributed their time, knowledge, and energy to bringing this document to completion, particularly to the members of the AIUM's Clinical Standards Committee. The AIUM represents the entire range of clinical and basic science interests in medical diagnostic ultrasound and, with hundreds of volunteers, the AIUM has promoted the safe and effective use of ultrasound in clinical medicine for more than 50 years. This document, and others like it, will continue to advance this mission. AIUM standards are intended to provide the medical ultrasound community with guidelines for the performance and recording of high quality ultrasound examinations. The standards reflect what the AIUM considers the minimum criteria, but are not intended to establish a legal standard of care. AIUM‐accredited practices are expected to generally follow the standards with the recognition that deviations from the standards will be needed in some cases depending on patient needs and available equipment. Practices are encouraged to go beyond the standards to provide additional service and information as needed by their referring physicians and patients.