Relationship between image quality and ultrasound exposure level in diagnostic US devices.

Abstract

Ultrasonographic B-mode images were obtained at various exposure levels with three real-time diagnostic scanners. Adult human and tissue-equivalent phantom images were compared in terms of diagnostic content and depth of penetration. For the exposure level settings used, spatial-peak pulse-average intensities ranged from approximately 10 to 500 W/cm2. At the 3.50-3.75-MHz nominal frequencies used in the study, images of the human abdomen showed little discernible change in quality with varying exposure levels. However, phantom tests confirmed that depth of penetration is a function of exposure level. The results suggest that a judicious use of exposure level and receiver gain controls can be a practical means for minimizing patient exposure to ultrasound without sacrifice of diagnostic effectiveness.

Measured acoustic intensities for clinical diagnostic ultrasound transducers and correlation with thermal index

“…Although no previous study has assessed the relationship between TIB and ultrasound intensity, previous papers have pointed out various limitations of TI 22,[27][28][29] . One previous study examined the effect of output power settings on image quality, and found considerable discrepancy in I SPTA.3 values between scanners with similar output power settings 30 . That study, however, predates TI, so no direct comparisons could be made.…”

Safety Aspects of Perinatal Ultrasound

“…Der Vorteil einer sicheren und umsichtigen sonografischen Bildgebung in der Schwangerschaft besteht darin, dass der Ultraschalluntersucher und die schwangere Frau sicher sein können, dass klinisch relevante Informationen gewonnen werden, während das Risiko für mögliche negative Bioeffekte auf ein Minimum reduziert wird. Die Einschränkung besteht darin, dass eine reduzierte Leistungseinstellung die Bildqualität beeinträchtigen kann, obwohl Studien darauf hinweisen, dass dieser Effekt vernachlässigbar ist [21,22]. Eine reduzierte Ausgangsleistung sollte den Benutzer ermutigen, Frequenz, Fokus, Gain und Zoom aktiv anzupassen, um die Bildqualität zu the exposure to high-intensity modalities, such as Doppler, should be used only for as long as needed.…”

“…The advantages of safe and prudent ultrasound imaging of the neonate are that the ultrasound examiner and the parents may rest assured that clinically relevant information is being obtained while the risk for potential negative bioeffects is being kept to a minimum. The limitation is that a reduced power output setting may decrease image quality, although studies indicate that this effect is negligible [21,22]. A reduced output power may even encourage the user to actively adjust frequency, focus, gain, and zoom to optimize image quality, thus achieving better diagnostic imaging.…”

Prenatal exposure to ultrasound waves: is there a risk?

“…Fourth, there is some evidence that any positive temperature differential for any period of time may have some effect, in other words that there may be no threshold for hyperthermia‐induced birth defects29. Fifth, there is a possibility of further relaxing or completely eliminating present FDA regulations on the premise that greater acoustic outputs would improve diagnostic capability under certain circumstances30, although this, in reality, is entirely unproven31. Finally, there is disquieting data indicating that practitioners are generally unaware not only of the TI, including its meaning and utility, but also of the MI and of bioeffects and safety‐of‐ultrasound issues, in general32, 33.…”