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Chapter 24 Bioeffects

Terms in this set (33)

Bioeffects
Biophysical results of the interaction of sound waves and tissue
hydrophone
A small needle with a
Piezoelectric crystal at its end.

Can quantity amplitude, period, Pulse duration, and pulse repetition.

Measures the pressure in a sound beam.
Calorimeter
A transducer which turns acoustic energy into heat. When total heat gain is measured along with the time that it took to obtain the heat, the total power of the US beam can be calculated.
Thermocouple
A small device embedded in absorbing material. The US energy is converted into heat, and the temperature change is measured. The intensity at specific locations are measured.
liquid crystals
change in color based on change in temperature, provides insight to strength and shape of sound beam.
In vivo
In the natural setting
in vitro
Anything else
Dosimetry
science of identifying and measuring the characteristics of an US beam that are relevant to its potential for producing bioeffects.
American Institute of ultrasound in medicine (AIUM)
multidisciplinary membership organization that includes all areas of sonographic practice involved in the establishment of standards and practices
AIUM-
FDA-
-evaluates science
-regulates
Bioeffects intensity limit
SPTA (spatial peak temporal average)
Difficult to study in vivo due to
Absorption, scattering, and reflection
What has the greatest effect on patient exposure
Exam duration
exam duration has the greatest effect on
patient exposure
Lowest output intensities are with
gray scale imaging
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