# ULTRASOUND DOSIMETRY IN HUMAN OB/GYN EXAMINATION

> **NIH NIH R01** · UNIVERSITY OF CINCINNATI · 1994 · $151,647

## Abstract

Despite the almost universal use of diagnostic ultrasound in obstetrical
patients in the United States, critical information regarding in situ fetal
ultrasonic exposure levels, the specific sensitivity of individual organs
to ultrasound, threshold exposure levels for biologic effects, cumulative
dose-effects from multiple exposures, the effect of patient size and stage
of gestation, is at best, minimally available.  Ultrasound is a mechanical
form of radiation with direct physical/force effects on biological tissues
as well as indirect thermal effects from tissue energy absorption.  High
intensity ultrasound has well defined bioeffects and biohazards; but except
for our data obtained over the preceding three years, the relationship
between in vitro maximum values of ultrasonic field quantities measured and
in vivo exposure levels in diagnostic studies remains unknown.  We have
constructed a specialized in vivo exposimetry system, developed and tested
customized software and using specially fabricated hydrophones, determined
selected first-order and second-order ultrasonic field quantities during a
routine reproductive ultrasound examination of the ovary, embryo and fetus.
Our sonographic measurements in the "ovarian group" yielded mean ultrasound
beam path distances of 7.6 cm. in the presence of a distended bladder and
7.0 cm. in the presence of an empty bladder with an average group insertion
loss of 6.2 dB and 7.3 dB; similar values for the "embryo group" were 8.35
cm. and 6.36 cm. respectively with an average group insertion loss of 5.7
dB and 9.9 dB; and for the "fetal group" were 9.6 cm. and 8.0 cm.
respectively with an average group insertion loss of 8.7 dB and 8.9 dB.
Using a Fixed Attenuation Model, the values were 2.98 dB/MHz, 2.71 dB/MHz
and 4.17 dB/MHz for the ovarian, embryo and fetal studies respectively;
whereas for the Overlying Tissue Model the respective values were 0.72
dB/cm-MHz, 0.65 dB/cm-MHz and 0.59 dB/cm-MHz.  These data are both specific
and unique in that they have been systematically obtained in situ.
Although it is reassuring to note that these experimentally obtained human
in situ data are generally consistent with some of the mathematical models
proposed in the past, there are several major differences noted with
respect to worst-case modelling and the fundamental reasons as to why there
are similarities and differences between groups and bladder state
conditions are not yet unknown.  Using our now established methodology of
placing the specially fabricated hydrophones in the uterine cavity of
appropriate first trimester (embryo) and second trimester (fetal) pregnant
patients and customized instrumentation, we will insonate the products of
conception using commercial diagnostic ultrasound systems and:  1.
Determine the maximum values of ultrasonic quantities to which the human
embryo and fetus are exposed during a pulsed Doppler (including colorflow
Doppler) ultrasound examination, 2. Use our experimentally obtained ...

## Key facts

- **NIH application ID:** 2198302
- **Project number:** 5R01HD021687-07
- **Recipient organization:** UNIVERSITY OF CINCINNATI
- **SAM.gov UEI:** DZ4YCZ3QSPR5
- **Principal Investigator:** TARIQ A SIDDIQI
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1994
- **Award amount:** $151,647
- **Award type:** 5
- **Project period:** 1987-09-01 → 1995-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/2198302

## Citation

> US National Institutes of Health, RePORTER application 2198302, ULTRASOUND DOSIMETRY IN HUMAN OB/GYN EXAMINATION (5R01HD021687-07). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/2198302. Licensed CC0.

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