7.6.2011 9:31:43 MarkétaP + 4 dcerky
Re: Škodlivost ultrazvuku
Tohle je asi 10 let starý text o srovnání doptonu a zobrazovacího UZ:
The Hitachi unit ... has a trans-abdominal probe that transmits at 3.5 MHz. The industry standard for obstetrical Dopplers is either 2 or 3 MHz. Imex in fact sells both. Higher probe frequencies that we sell such as 5 and 8 MHz are used for vascular applications and are labeled "Not Designed For Fetal Use."
In addition, I would like to point out that the FDA limit for power intensity emitted by a continuous wave ultrasound for fetal use is 0.094 watts per square centimeter. The FDA power intensity limit for pulsed wave ultrasound for fetal use is 190 watts per square centimeter. The power emitted by a Doppler can be 2,000 times less than an imager! Imex 3 MHz probes emit 0.009 watts per square centimeter, a factor of ten times less than the FDA limit.
Lastly, I also would like to point out that the duration of an auscultatory Doppler exam typically lasts less than a minute. Though it is exciting to
hear your baby""s heartbeat since there is nothing to see, the exam does not take very long. At the demonstration, I understand you watched the twins
for at least 20 minutes. Taken with the above power limits, this can be analogous to watching a night light for a minute as compared to watching a photographer""s strobe light for 20 minutes.