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Transducers
Chapter 8 Edelman
| Question | Answer |
|---|---|
| Definition of transducer | Any device that converts one form of energy into another |
| Transducers have what two functions? | Transmission and reception |
| During transmission, electrical energy from the system is converted into what? | Sound |
| During reception, the reflected sound pulse is converted into what? | Electricity |
| The property of certain materials to create a voltage when they are mechanically deformed or when pressure is applied to them is called what? | The piezoelectric effect |
| Materials which convert sound into electricity (and vice versa) are called what? | Piezoelectric materials or ferroelectric |
| Synonyms for PZT | Ceramic, active element, or crystal |
| The main function of the transducer case | Protect the internal components from damage. It also insulates the patient from electrical shock |
| Electrical shield | A thin metallic barrier lining the inside of the case that prevents spurious electrical signals in the air from entering the transducer |
| Acoustic insulator | A thin barrier of cork or rubber that isolates or "uncouples" the internal components of the transducer from the case and keeps vibrations from inducing an electrical voltagein the PZT |
| PZT | The active element of the probe. It is one half wavelength thick. The shape of the active element(s) determines the characteristics of the sound beam |
| Wire | Provides an electrical connection between the PZT and the US system. |
| Matching layer | Increases the efficiency of the sound energy transfer between the active element and the human body. It protects the active element and is 1/4 the wavelength thick. |
| Backing material aka damping element | Bonded to the back of the active element, it reduces the ringing/vibrating of the PZT. It restricts the deformation of the PZT. The resulting sound pulse is shortened in duration and length. |
| Damping enhances what? | Axial resolution |
| Three consequences of using backing material are what? | 1. decreased sensitivity, 2. wide bandwidth and 3. low quality factor |
| Decreased sensitivity that occurs with dampening means what? | During reception, transducers are less able to convert low level sound reflections into meaningful electrical signals. |
| True or false, imaging probes produces pulses with wide bandwidth. | True |
| True or false, other probes such as continuous wave Doppler or therapeutic US do not use backing material and therefore produce narrow bandwidth pulses. | True |
| Bandwidth is the range of what in the pulse? | Frequencies |
| True or false, a single frequency tone is called a resonant frequency. | True |
| True or false, as a general rule, long duration events are narrow bandwidth, whereas short duration events are wide bandwidth (broadband). | True |
Created by:
gillybruursema
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