Sonicaid FM800 Encore Series Instructions for Use
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19.9
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Ultrasound safety considerations
280B
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 FM800 Encore series 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 FM800 Encore series
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 FM800 Encore series 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.
Summary of Contents for Sonicaid FM800 Series
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