10 Questions
What frequency range is considered as ultrasound in medical applications?
20 kHz to 1 GHz
What principle is the ultrasound transducer based on?
Piezoelectric principle
What happens when an electric potential difference is applied across a piezoelectric crystal in a transducer?
The crystal vibrates to produce mechanical energy
What device uses ultrasound waves to generate an image of soft tissues in the body?
SONAR
Which of the following is NOT a type of ultrasound transducer?
Transverse
What is the role of water or jelly paste during an ultrasound scan?
To create a good impedance matching between the transducer and skin
What kind of waves does the ultrasound transducer emit into the body?
Ultrasound waves
What happens to ultrasound waves after they are transmitted into the body during a SONAR scan?
They reflect off internal structures and are received by the transducer
Which type of transducer is associated with high frequency?
Linear
In a clinical application, what does the push-pull action of the transducer cause?
Regions of compression and rarefaction
Study Notes
Ultrasound Waves
- Ultrasound frequency ranges from 20kHz to 1GHz for medical applications
- Ultrasound frequency is greater than the upper limit of human hearing
- SONAR stands for SOund NAvigation and Ranging
US Generation
Piezoelectric Principle
- The ultrasound signal is generated and detected by the sensor based on the piezoelectric principle
- The transducer converts electrical energy to mechanical (ultrasound) energy and vice versa
- Many crystals can be used to generate ultrasound waves, where AC voltage produces a vibration of the crystal
- In clinical application, the transducer acts as a piston, producing regions of compression and rarefaction when an electric potential difference is applied
Sonography
- Sonography is a device that uses US waves to generate an image of a particular soft tissue structure in the body
Transducers Types
- Transducers convert electrical energy to mechanical (ultrasound) energy and vice versa
- Different types of transducers vary in frequency and footprint, including:
- Curvilinear
- Phased Array
- Linear
- Hockey Stick
Basic Principle of SONAR
- In medical diagnosis, ultrasound pulses are transmitted into the body by placing the US transducer in close contact with the skin
- Water or a jelly paste is used to eliminate air and create good impedance matching between the transducer and skin
- The transducer sends out pulses of US, which travel through the body and reflect off internal structures
- The reflected waves are received by the same transducer, and the weak signal is amplified and displayed on an oscilloscope
Learn about ultrasound waves, their frequency range, and how they are generated using the piezoelectric principle.
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