WHO Study Group on Training in Diagnostic Ultrasonography

The WHO Study Group on Training in Diagnostic Ultrasonography (Essentials, Principles and Standards), met in Philadelphia, Pennsylvania, USA on March 22-26, 1996 to consider methods of improving the training and clinical performance of medical doctors and technologists using diagnostic ultrasound for medical applications.

The meeting was organised with the collaboration and financial support of the World Federation for Ultrasound in Medicine and Biology (WFUMB). The meeting was opened by Dr. A. Wasunna, Director, Programme on Health Technology WHO, Geneva, on behalf of the Director General of the WHO, Dr. Nakajima.

Dr. V. Volodin, from Geneva, briefly outlined the recommended procedure for the meeting. Professor B. B. Goldberg, President, WFUMB, was elected President of the Study Group. Dr. M. W. Wachira was elected Vice- President, and Dr. C. B. Merritt was elected Rapporteur.

The study group represented a wide variety of expertise on the topic. In addition to the WHO Geneva Office representatives, the group consisted of physicians, sonographers, physicists and engineers from all over the world.

Several papers highlighting currently used training procedures and needs in different countries were presented by delegates from South East Asia, including China, Japan and Indian subcontinent, Australia, North and South America, and Europe.

The ensuing discussion formed a background for a final document which was approved by the workshop participants. To prepare this document different working groups were formed; each group prepared its final draft for discussion. The drafts addressed the following topics:

world situation: training in diagnostic ultrasonography
speciality ultrasound including specific recommendations for individual specialities
ultrasound training for sonographers and other allied health personnel
curriculum for basic sciences and instrumentation
training centres and resources needed
recommendations

Recognising the importance of ultrasound as the fastest growing diagnostic imaging modality, the workshop participants emphasised the need for uniform training for sonographers and other allied health personnel such as nurses, midwives, radiographers, nuclear medicine technologists, physician's assistants and cardiac technologists. It has been stressed, however, that as proper ultrasound diagnosis is very operator-dependent, appropriate training is essential.

One of the study groups developed a basic curriculum for physics and instrumentation. As this aspect of training appears to be of particular interest to medical and biological engineers, it is briefly summarised below.

The developed curriculum highlights that understanding of the basic principles of physics and knowledge of instrumentation are essential to achieve the maximum benefit of ultrasound technology for diagnosis and to avoid possible pitfalls that may render diagnosis useless. Accordingly, the proposed curriculum focused on two main objectives.

To provide the ultrasound practitioner with sufficient knowledge of ultrasound fundamentals to effectively operate an ultrasound scanner, and to provide a diagnostically useful image with appropriate regard to issues of benefit and potential risks to patients' safety.
To provide an understanding of the nature of artefacts that may be present in images produced in order to avoid a misdiagnosis.

Basic physics, including bio-effects and safety, and imaging methods and equipment, including quality assurance, constitute the major topics of the curriculum. It was proposed that the basic curriculum will be delivered within 20 hours of lectures. The advanced curriculum will require 20 additional hours of classes.

The developed curriculum stresses that basic physical principles relating to ultrasound and its interaction with tissues should be mastered. This knowledge must include basic terminology, physical relationships involving wave pressure amplitude, intensity, attenuation, perpendicular and oblique angle of incidence, scattering and the range equation. In addition, transducer construction and the effects of the sound waves produced should be discussed, together with methods of focusing and issues associated with resolution and trade-off between the resolution and tissue penetration. Finally, artefacts , bio-effects and safety and the principles of scanning are to be included.

Level II training is to be tailored to the needs of individuals with an MD. Here the curriculum includes advanced physics of ultrasound imaging, terminology, bio-effects, safety, on-screen output display standards and their interpretation, ultrasound instrumentation, operation of the equipment, set-up and quality assurance. Instrumentation knowledge covers all B-mode imaging, pulsed wave and continuous wave Doppler, and colour and power Doppler.

The advanced level curriculum document further stresses the importance of understanding and appropriate knowledge of statistics and computer science. Finally, the document indicates the need for continuing medical education and follow-up training.

The document stresses that even established well advanced teaching centres should be encouraged to invite external lecturers to ensure fostering of new ideas and to constantly improve the quality of the curriculum. In addition, the potential advantage of using distant learning and multimedia approach was highly recommended.

As it appears from the above, implementation of these curricula will require the active involvement of biomedical engineers and the development of appropriate curricula. Biomedical engineers are well suited for this task as they usually combine excellent theoretical knowledge with hands-on practical experience.

The development of the curricula should take into account the fact that ultrasound is now considered to be the primary imaging modality for the detection of most gynaecological, hepatic, biliary, pancreatic, splenic and renal disease. Ultrasound diagnosis is also extensively used in the examination of the scrota, bladder and prostate. In addition, in many developing countries, sonography may have an important application as an epidemiological screening tool and as a diagnostic procedure in parasitic diseases such as amoebiasis, schistosomiasis and echinococcosis.

In light of the above, it appears that the delivery of the recommended curricula will generate a need for engineers who not only must possess the required professional background, but who are also able to develop exciting curricula, carefully tailored to a generally non-engineering audience.

Indeed, Chapter 4 of the workshop document stresses the need for high qualified teachers. Teachers should regularly attend ultrasound meetings and conferences to ensure that they remain in touch with this rapidly developing field.

The proposed curricula also address the issue of a basic knowledge of biology. This knowledge is essential in understanding the origin of tissue-reflecting properties and for an appreciation of the issues involved in bio-effects and safety. Again, this would create a need for biological science instructors with appropriate physical acoustics backgrounds.

At present, it appears that there is a limited number of individuals who are adequately trained to teach the proposed curricula. This indicates a need to establish training support groups, comprising individuals who would combine scientific and didactic knowledge. Such individuals would also be able to provide appropriate pedagogical assistance which would enable engineers to deliver high-quality lectures tailored to the specific audience.

The development of intensive training programmes for teachers is desirable and has already been provided in some countries, e.g. a prototype of such a programme has been produced at the Jefferson Research and Education Institute, Philadelphia, Pennsylvania. In this programme, individuals not only receive an update of the clinical and technical knowledge in the fields in which they are going to teach, but also instruction in the methods and techniques of teaching. These programmes are a model for 'teach a teacher' programmes and should be developed at major training centres throughout the world.

Regardless of their level of expertise, all teachers and practitioners of ultrasound must pursue continuing education through refresher courses, as well as updates on new technology. This is particularly important if individuals wish to expand their knowledge into new areas of interest.

In addition, (biomedical) engineers with a background in imaging instrumentation will be needed to provide appropriate technical back-up for the physicians, sonographers or other health allied personnel involved in ultrasound diagnosis.

A final version of the comprehensive report approved by the members of the Study Group will be published shortly and will be made available to all interested parties. The report concludes with a list of recommendations.

Appropriate training of the users of diagnostic medical ultrasound equipment is the most important requisite for the improvement and rational use of diagnostic ultrasound in clinical practice. The use of ultrasound by individuals with inadequate competence adds to the likelihood of unnecessary patient examination and misdiagnosis, with substantial negative impact on the healthcare system.
It is highly desirable that the purchase and use of medical ultrasound equipment is restricted to those who have acquired and passed an adequate training in diagnostic ultrasound. The Study Group reinforces the recommendation of the WHO Scientific Group on The Future Use of New Imaging Technologies in Developing Countries (TRS 723) that 'purchase of ultrasound equipment without provision for the proper training of an operator is contrary to a good healthcare practice and is unlikely to be cost-effective'.
The Study Group strongly recommends that appropriate curricula, such as those included in their document, should be adopted for general, advanced and specialised training of medical doctors and allied personnel who use diagnostic ultrasound.
The WHO, international, governmental, non-governmental organisations and professional organisations should be actively involved in the development of high quality training programmes. This can be achieved by setting high training standards, organisation and carrying out of training courses, certification of trainees, and organising continuing education programmes for both teachers and programme participants.

PETER A. LEWIN, MSc, PhD