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Instructions For Use
EN
Appendix 2 - Ultrasound Safety Considerations
General
Diagnostic ultrasound has been in use for over 35 years with no confirmed adverse effects on patients or
instrument operators at the intensities typical of present diagnostic instruments. However, available data are
not wholly conclusive, and the possibility remains that biological effects may be identified in the future.
Because fetal tissue could be more sensitive to biological effects by reason of rapid cell division, it is
particularly desirable that ultrasound exposure of pregnant subjects be kept to a minimum.
Medical and scientific authorities therefore recommend that ultrasound procedures be performed in accordance
with the “ALARA” principle, which states that the energy delivered to the patient should always be kept As Low
As Reasonably Achievable.
The transmitted acoustic power of the Sonicaid Team3 fetal monitor is fixed and cannot be adjusted by the
operator. Therefore, the user can best observe the ALARA principle by ensuring that each examination is
medically indicated and by limiting the duration of the study to the extent appropriate for the clinical objectives.
Acoustic output data for the transducers for use with the Sonicaid Team3 fetal monitors is summarized in the
following tables. The values given are based on measurements in water using a calibrated hydrophone and are
stated as the estimated de-rated intensities. The de-rated intensity constitutes the most biologically relevant
parameter available, since true determinations of the actual absorbed dose in tissue would require invasive
measurement techniques. The de-rated intensity is, therefore, calculated mathematically using a de-rating
factor consisting of a constant (the assumed attenuation coefficient) and allowing for the frequency of the
transducer and the distance from the transducer face to the measurement hydrophone.
The calculated de-rated intensity values for the Sonicaid Team3 fetal monitors compare very favourably with
previously reported acoustic safety data for Doppler ultrasound instruments and are appropriate for all clinical
applications recommended in this manual.
At present, there is a clear consensus that the benefits to patients of prudent use of diagnostic ultrasound
outweigh the risks that may be present. See:
a)
Report No. 24, National Council on Radiation and Protection: biological effects of ultrasound, clinical
effects and observations.
b)
Ziskin M.C., in World Policies on the Use of Diagnostic Ultrasound in Obstetrics: The American Institute
of Ultrasound Policy and Statement on Safety. Ultrasound in Medicine and Biology 12: 711-714, 1986.
