UltraSound - Technology Information PortalThursday, 27 July 2017
Info
  Sheets



Out-
      side
 




 
 'Piezoelectric Effect' 
SEARCH FOR   
 
  12345ABCDEFGHIJKLMNOPQRSTUVWZ
Result : Searchterm 'Piezoelectric Effect' found in 1 term [] and 2 definitions [], (+ 2 Boolean[] results)
1 - 5 (of 5)     
Result Pages : [1]
US Resources  
Examinations - Fetal - Research Labs - Ultrasound Guided Interventions - Ultrasound Therapy - Journals
 
Piezoelectric EffectMRI Resource Directory:<br> - UltraSound Physics -
 
Piezo means pressure, so piezoelectric means that pressure is generated when electrical energy is applied to a quartz crystal. When electrical energy is applied to the face of the crystal, the shape of the crystal changes as a function of the polarity of the applied electrical energy. As the crystal expands and contracts it produces compressions and rarefactions, and creates sound waves. When this material is struck by sound waves it creates electrical currents.
Thus, a piezoelectric crystal can produce a pulse of mechanical energy (pressure pulse) by electrically exciting the crystal (transmitter), and they can produce a pulse of electrical energy by mechanically exciting the crystal (receiver). This ultrasound physics principle is called the piezoelectric effect (pressure electricity), which was discovered by Pierre and Jacques Curie in 1880, and is used to generate ultrasound waves. Instead of quartz crystals, piezoelectric ceramics such as barium titanate or lead zirconate titanate are also used, which are crystalline materials with similar piezoelectric properties.
See also Temporal Peak Intensity.
Radiology-tip.comPhotoelectric Effect,  Air Kerma
spacer
Radiology-tip.comRelaxation Effect
spacer
• Related Searches:
    • Echo
    • Sound
    • Gray Scale
    • Ultrasound
    • Frequency

 Further Reading:
  Basics:
Physics Tutorial: Ultrasound PhysicsOpen this link in a new window
   by www.physics247.com    
US Resources  
UltraSound Technician and Technologist Jobs - Manufacturers - Rental - Abdominal - Pediatric - Pregnancy
 
History of UltrasoundMRI Resource Directory:<br> - History of UltraSound -
 
point In 1880 the Curie brothers discovered the piezoelectric effect in quartz. Converse piezoelectricity was mathematically deduced from fundamental thermodynamic principles by Lippmann in 1881.
point In 1917, Paul Langevin (France) and his coworkers developed an underwater sonar system (called hydrophone) that uses the piezoelectric effect to detect submarines through echo location.
point In 1935, the first RADAR system was produced by the British physicist Robert Watson-Wat. Also about 1935, developments began with the objective to use ultrasonic power therapeutically, utilizing its heating and disruptive effects on living tissues. In 1936, Siemens markets the first ultrasonic therapeutic machine, the Sonostat.
point Shortly after the World War II, researchers began to explore medical diagnostic capabilities of ultrasound. Karl Theo Dussik (Austria) attempted to locate the cerebral ventricles by measuring the transmission of ultrasound beam through the skull. Other researchers try to use ultrasound to detect gallstones, breast masses, and tumors. These first investigations were performed with A-mode.
point Shortly after the World War II, researchers in Europe, the United States and Japan began to explore medical diagnostic capabilities of ultrasound. Karl Theo Dussik (Austria) attempted to locate the cerebral ventricles by measuring the transmission of ultrasound beam through the skull. Other researchers, e.g. George Ludwig (United States) tried to use ultrasound to detect gallstones, breast masses, and tumors. This first experimentally investigations were performed with A-mode. Ultrasound pioneers contributed innovations and important discoveries, for example the velocity of sound transmission in animal soft tissues with a mean value of 1540 m/sec (still in use today), and determined values of the optimal scanning frequency of the ultrasound transducer.
point In the early 50`s the first B-mode images were obtained. Images were static, without gray-scale information in simple black and white and compound technique. Carl Hellmuth Hertz and Inge Edler (Sweden) made in 1953 the first scan of heart activity. Ian Donald and Colleagues (Scotland) were specialized on obstetric and gynecologic ultrasound research. By continuous development it was possible to study pregnancy and diagnose possible complications.
point After about 1960 two-dimensional compound procedures were developed. The applications in obstetric and gynecologic ultrasound boomed worldwide from the mid 60’s with both, A-scan and B-scan equipment. In the late 60’s B-mode ultrasonography replaced A-mode in wide parts.
point In the 70’s gray scale imaging became available and with progress of computer technique ultrasonic imaging gets better and faster.
point After continuous work, in the 80’s fast realtime B-mode gray-scale imaging was developed. Electronic focusing and duplex flow measurements became popular. A wider range of applications were possible.
point In the 90’s, high resolution scanners with digital beamforming, high transducer frequencies, multi-channel focus and broad-band transducer technology became state of the art. Optimized tissue contrast and improved diagnostic accuracy lead to an important role in breast imaging and cancer detection. Color Doppler and Duplex became available and sensitivity for low flow was continuously improved.
point Actually, machines with advanced ultrasound system performance are equipped with realtime compound imaging, tissue harmonic imaging, contrast harmonic imaging, vascular assessment, matrix array transducers, pulse inversion imaging, 3D and 4D ultrasound with panoramic view.
read more

Radiology-tip.comDiagnostic Imaging
spacer
Radiology-tip.comMRI History
spacer

 Further Reading:
  News & More:
Physics Tutorial: Ultrasound PhysicsOpen this link in a new window
   by www.physics247.com    
A-Mode Area RatioOpen this link in a new window
   by www.wildultrasound.com    
US Resources  
Devices Machines Scanners Systems - Non-English - Online Books - Fetal - Research Labs - Vascular
 
TransducerInfoSheet: Probes/Transducers
Intro,
Probes, 
TransducersMRI Resource Directory:<br> - Probes Transducers -
 
A transducer is a device, usually electrical or electronic, that converts one type of energy to another. Most transducers are either sensors or actuators. A transducer (also called probe) is a main part of the ultrasound machine. The transducer sends ultrasound waves into the body and receives the echoes produced by the waves when it is placed on or over the body part being imaged.
Ultrasound transducers are made from crystals with piezoelectric properties. This material vibrates at a resonant frequency, when an alternating electric current is applied. The vibration is transmitted into the tissue in short bursts. The speed of transmission within most soft tissues is 1540 m/s, producing a transit time of 6.5 ms/cm. Because the velocity of ultrasound waves is constant, the time taken for the wave to return to the transducer can be used to determine the depth of the object causing the reflection.
The waves will be reflected when they encounter a boundary between two tissues of different density (e.g. soft tissue and bone) and return to the transducer. Conversely, the crystals emit electrical currents when sound or pressure waves hit them (piezoelectric effect). The same crystals can be used to send and receive sound waves; the probe then acts as a receiver, converting mechanical energy back into an electric signal which is used to display an image. A sound absorbing substance eliminates back reflections from the probe itself, and an acoustic lens focuses the emitted sound waves. Then, the received signal gets processed by software to an image which is displayed at a monitor.
Transducer heads may contain one or more crystal elements. In multi-element probes, each crystal has its own circuit. The advantage is that the ultrasound beam can be controlled by changing the timing in which each element gets pulsed. Especially for cardiac ultrasound it is important to steer the beam.
Usually, several different transducer types are available to select the appropriate one for optimal imaging. Probes are formed in many shapes and sizes. The shape of the probe determines its field of view.
Transducers are described in megahertz (MHz) indicating their sound wave frequency. The frequency of emitted sound waves determines how deep the sound beam penetrates and the resolution of the image. Most transducers are only able to emit one frequency because the piezoelectric ceramic or crystals within it have a certain inherent frequency, but multi-frequency probes are also available.
See also Blanking Distance, Damping, Maximum Response Axis, Omnidirectional, and Huygens Principle.
Radiology-tip.comTransmitter
spacer

• View the news results for 'Transducer' (6).



 Further Reading:
  Basics:
Testing Diagnostic Ultrasound Probes For Bad CrystalsOpen this link in a new window
Saturday, 19 September 1998   by www.pamia.org    
  News & More:
Ultrasound beamforming and image formation(.pdf)Open this link in a new window
2007   by dukemil.bme.duke.edu    
Transmission Line Matrix (TLM) modelling of medical ultrasound(.pdf)Open this link in a new window
   by www.era.lib.ed.ac.uk    
US Resources  
Non-English - Hospitals - Contrast Agents - Modes - Devices Machines Scanners Systems - Kidney
 
Real-Time TransducerInfoSheet: Probes/Transducers
Intro,
Probes, 
TransducersMRI Resource Directory:<br> - Probes Transducers -
 
Transducers used for the real-time mode are different than for the A-mode, B-, or M-modes. A linear array transducer with multiple piezoelectric crystal elements that are different arranged and fired, transmits the needed larger sound beam.
A subgroup of x adjacent elements (8-16; or more in wide-aperture designs) is pulsed simultaneously; the inner elements pulse delayed with respect to the outer elements. The interference of the x small divergent wavelets generates a focused beam. The delay time determining the focus depth of a real-time transducer can be changed during imaging.
Similar delay factors applied during the receiving phase, result in a dynamic focusing effect on the return. This forms a single scan line in the real-time image. To produce the following scan line, another group of x elements is selected by shifting one element position along the transducer array from the previous group. This pattern is then repeated for the groups along the array, in a sequential and repetitive way.
spacer

 Further Reading:
  Basics:
Real-time B-mode ultrasound quality control test procedures a Report of AAPM Ultrasound Task Group No. 1Open this link in a new window
   by www.aapm.org    
US Resources  
Ultrasound Guided Interventions - Doppler UltraSound - Calculation - Education pool - - Services and Supplies
 
Ultrasound PhysicsMRI Resource Directory:<br> - UltraSound Physics -
 
Ultrasound physics is based on the fact that periodic motion emitted of a vibrating object causes pressure waves. Ultrasonic waves are made of high pressure and low pressure (rarefactional pressure) pulses traveling through a medium.

Properties of sound waves:
point wavelength;
point frequency;
point amplitude;
point velocity.
The speed of ultrasound depends on the mass and spacing of the tissue molecules and the attracting force between the particles of the medium. Ultrasonic waves travels faster in dense materials and slower in compressible materials. Ultrasound is reflected at interfaces between tissues of different acoustic impedance e.g., soft tissue - air, bone - air, or soft tissue - bone.
The sound waves are produced and received by the piezoelectric crystal of the transducer. The fast Fourier transformation converts the signal into a gray scale ultrasound picture.

The ultrasonic transmission and absorption is dependend on:
point absorption;
point reflection;
point backscattering;
point refraction.
See also Sonographic Features, Doppler Effect and Thermal Effect.
Radiology-tip.comIonizing Radiation,  X-Ray Spectrum
spacer
Radiology-tip.comMagnetic Resonance
spacer

US Resources  
Jobs - Prenatal - UltraSound Technician and Technologist Jobs - Probes Transducers - Manufacturers - Resources
 
Related Searches:
 • Piezoelectric Crystal
 • Doppler Effect
 • Ultrasound
 • Gray Scale
 • Thermal Effect
SEARCH FOR   
 
  12345ABCDEFGHIJKLMNOPQRSTUVWZ
     1 - 5 (of 5)     
Result Pages : [1]
 Random Page
 
Share This Page
FacebookTwitterLinkedIn

US-TIP    
Community   
User
Pass
Forgot your UserID/Password ?  


Look
      Ups



UltraSound - Technology Information Portal
Member of SoftWays' Medical Imaging Group - MR-TIP • Radiology-TIP • US-TIP • The-Medical-Market
Copyright © 2006 - 2016 SoftWays. All rights reserved.
Terms of Use | Privacy Policy | Advertising
 [last update: 2015-03-04 09:17:02]