|
|
|
| GUIDELINES FOR THE MANAGEMENT OF
SAFETY WHEN USING VOLUNTEERS & PATIENTS FOR PRACTICAL TRAINING IN
ULTRASOUND SCANNING |
|
 Introduction and scope |
| |
Practical experience of ultrasound
scanning forms an essential component of all training in clinical ultrasound.
Those in training may observe experienced and qualified practitioners carrying
out scanning, and, more importantly, use ultrasound equipment under the
guidance and supervision of a tutor, or other senior clinical colleague. During
training, they develop an understanding of the machine controls and settings
and a working knowledge of the purpose and outcome of altering the machine
settings. They also develop practical skills in carrying out a wide range of
clinical studies, obtaining images of optimum diagnostic quality and
interpreting and reporting findings.
Modern ultrasound scanners, when used in accordance with
guidelines published by BMUS, EFSUMB and WFUMB, do not give rise to substantial
concerns over safety. Nevertheless, it is possible to select operating
conditions on some equipment that are capable of warming tissue to a level
where adverse bio-effects may occur. The magnitude of the temperature rise
increases with the length of exposure and with the ultrasound output. In
addition, it is known that tissues can be damaged close to any gas bodies
exposed to high amplitude pulses of ultrasound, for example at the lung surface
or with micro-bubble contrast agents. A further aspect of safety management is
the inherent sensitivity of each type of tissue and the long-term relevance of
any adverse bio-effects. For example, exposure of embryonic tissues is critical
because they are rapidly proliferating, and because of the potential
developmental changes which may be caused. Exposure of fetal bone can result in
secondary warming of adjacent soft tissues, of particular importance to the
brain and spinal cord, especially with high-intensity Doppler beams.
It is important, therefore, to establish recommendations which, when followed,
will prevent trainee operators from using scanners at unnecessarily high output
levels, scanning for unduly long periods of time, or giving unjustifiable
exposure of critical target organs. These recommendations also ensure that the
lines of accountability for safe scanning during training are clear. They
should ensure that there is sufficient scope to enable practical scanning
skills to be developed within a managed and responsible framework.
Formal training programmes should include appropriate
teaching material on the safe use of ultrasound, the potential for bioeffects
and the rationale and means for limiting output. These guidelines do not define
a training curriculum relating to safety, but only set out to establish
operational criteria for safe practical training. |
| Overall responsibility and supervision |
| |
- Responsibility for the safety of patients and volunteers during practical
training in ultrasound scanning lies in the first instance with the tutor
supervising the scanning.
- The tutor should ensure that the trainee is competent in the safe
application of ultrasound before being allowed to scan without supervision.
- Where previously unknown pathology is detected during training scan on a
"normal" volunteer, there should be appropriate mechanisms in place
for reporting the findings and directing appropriate medical management. This
must include a clear strategy, so that if a medical problem is identified in a
volunteer that an appropriate referral system is in place. This will normally
be by contact with the general practitioner of the person concerned. This
strategy must be clear to a volunteer prior to participation in a scanning
session.
- Tutors should be aware of the particular needs for training when ultrasound
scanning is used for less common applications or research.
- The tutor should be aware of, and abide by, current BMUS, EFSUMB and WFUMB
safety guidelines.
|
| Informed consent |
| |
- The person being scanned should give informed consent for the procedure. It
is the tutor’s responsibility to ensure this is done.
- Patients being scanned for clinical reasons should be made aware that a
trainee is carrying out the examination. The patient should understand that
their quality of care would not be affected whether the trainee scans or not.
Verbal consent is acceptable.
- Healthy volunteers should give informed consent, ideally in written form.
The consent form should include a paragraph on the consequences of finding an
unforeseen abnormality and the strategy for subsequent management of the
problem.
|
| Management of acoustic output |
| |
- The tutor will ensure that the trainee avoids the use of excessive and
inappropriate exposure levels, particularly in obstetric applications and when
using spectral Doppler and colour Doppler imaging modes.
- The tutor will ensure that the time spent with an individual subject does
not exceed that necessary for the training need. It is recommended that the
total examination time is normally no more than twice that needed to carry out
a diagnostic scan.
- Wherever possible, training should be carried out using a scanner equipped
with a display of the two safety indices - Mechanical Index and Thermal Index.
The tutor should make sure the trainee is aware of the displayed safety
indices, their meaning, and their function in the management of safety.
- The trainee should be aware of the effect on machine output resulting from
changes in machine controls. This may be monitored during scanning by observing
the safety indices.
|
| Ultrasound contrast agents |
| |
- A number of ultrasound contrast agents are now available for patient use
under medical supervision and it is appropriate for ultrasound practitioners to
be trained in their use. Any such study should, however, be performed or
supervised by an experienced medical practitioner who is responsible for the
safe and appropriate use of these agents. As ultrasound contrast agents can
lower the threshold for acoustic cavitation, special attention should be paid
to the avoidance of excessive scanning at higher acoustic output, when
possible.
|
| REFERENCES: |
British Medical Ultrasound Society. Guidelines for the
safe use of diagnostic ultrasound equipment. BMUS Bulletin, August 2000.
WFUMB 1998. Conclusions and Recommendations on Thermal and Non-thermal
Mechanisms for Biological Effects. Ultrasound in Med. & Biol; 24:
Supplement 1, xv-xvi.
EFSUMB 2002, Clinical Safety Statement for Diagnostic Ultrasound (2002). |
|
|
|
|
|
|
|
Return to Safety
Statements Main Page