Bioeffects Flashcards
A small needle with the piezoelectric crystal at it’s end. The needle is placed in the ultrasound beam. It attaches to an oscilloscope and displays acoustic signals received by the crystal. It can quantitate amplitude, period, Pulse duration and pulse repetition period. It measures the pressure in a sound beam.
Hydrophone
A transducer which turns acoustic energy into heat. When the total heat gain is measured along with the time that it took to obtain the heat, the total power of the ultrasound beam can be calculated.
Calorimeter
A small device in bedded in absorbing material. The ultrasound energy is converted into heat, and this device measures the temperature change. The intensity at specific locations are measured by this device.
Thermocouple
This means in the patient.
In vivo
This means nonliving (in-glass)
In vitro
The science of identifying and measuring those characteristics of an ultrasound field which are especially relevant to its potential for producing biological effects.
Dosimetry
Bioeffects intensity limit: SPTA
100 mW/cm ² unfocused
1 W/cm ² focused
What has the greatest effect on patient exposure?
Exam duration
What type of ultrasound interrogation has the highest intensities?
Highest output intensity’s are used with pulsed Doppler.
What type of approach to studying bioeffects is characterized by a cause-effect relationship?
Mechanistic approach
What type of approach to studying bioeffects is characterized by an exposure – response relationship?
Empirical approach
When is the mechanical index more likely to produce cavitation, higher?
Peak rarefaction pressure and lower frequency.
Cavitation is more likely to occur in lung than other tissues.
Bubbles expand during rarefactions and the bubbles burst.
Transient cavitation, also called normal cavitation and inertial cavitation
What is the greatest risk from a cracked transducer housing?
Electrical shock
