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  • Ultrasound Basics

    Presented by: Matt Tomory mtomory@conquestimaging.com Conquest Imaging www.conquestimaging.com

    © 2016 Conquest Imaging

    http://www.conquestimaging.com

  • Agenda

    Introduction and Welcome

    Ultrasound Basics

    Ultrasound Types

    Building Blocks of a Diagnostic Ultrasound System

    © 2016 Conquest Imaging

  • Welcome to Ultrasound Basics training presented by Conquest Imaging. After completing this training you will:

    Understand the basic principles of diagnostic ultrasound.

    Be able to identify transducer types and their use.

    Understand the trade-offs with regard to image quality and resolution.

    Understand the different imaging modes.

    Be familiar with the basic building blocks of any ultrasound system.

    Be familiar with different systems and their intended use.

    Introduction and Welcome

    © 2016 Conquest Imaging

  • © 2016 Conquest Imaging

    Introduction to Ultrasound

    This module provides a basic review of ultrasound theory topics. After completing this module you will be familiar with the basic concepts needed to understand how ultrasound works.

    What is Ultrasound?

    Sound Types by Frequency Range

    What is the Piezoelectric Effect?

    Ultrasound Transducers

    Tissue Interactions

    Image Quality

  • © 2016 Conquest Imaging

    What is Ultrasound?

    It’s a sound wave with frequency higher than 20,000 Hz.

  • © 2016 Conquest Imaging

    What is Ultrasound?

     Humans can hear sound in the frequency range between 20 to 20,000 Hz or 20 KHz.

     Sound is a mechanical, longitudinal pressure wave that travels through a medium such as air, water or metal.

     What is the average speed of ultrasound waves in human tissue? 1540 m/s

     What is the average speed of ultrasound waves in outer space?

    Outer space has no medium for sound to travel through; it is a vacuum therefore: 0 m/s

  • © 2016 Conquest Imaging

    Frequency Range (Hertz)

    Designation Examples

    0-16 Hz Infrasound Seismic waves

    16Hz-20KHz Audible Sound Speech, music

    20KHz-10GHz Ultrasound Dolphins, medicine

    1MHz-20MHz Medical Ultrasound Ultrasound Imaging

    !0GHz-10TH Hyper sound Acoustic Microscopy

    500 Hz 1000 Hz

    20000 Hz

    22000 Hz

    Sound Types by Frequency Range

  • © 2016 Conquest Imaging

    Ultrasound Applications

    Clinical Application Imaging Modes Used For:

    Radiology 2D Gall bladder, kidney, liver, spleen breast and thyroid

    Cardiology 2D, CW, AUX CW, PW Doppler and Color Doppler

    Noninvasive evaluation of heart function

    Vascular 2D, Color Doppler and PW Doppler Detection of blood flow and evaluation of any abnormalities

    OB/GYN 2D, M, PW Doppler, and Color Doppler

    Viewing fetal structures such as heart, kidneys and maternal structures such as ovaries, fallopian tubes and uterus

  • © 2016 Conquest Imaging

    By using piezoelectric elements that generate an ultrasound wave in response to an electrical pulse.

    The ultrasound wave then travels through a medium such as the human body.

     Some of its energy gets reflected back toward the source.

    How Do We Generate an Ultrasound Wave?

  • © 2016 Conquest Imaging

     Piezoelectricity is the ability of certain materials to generate an electric potential in response to applied mechanical stress.

     The word is derived from the Greek piezo or piezein, which means to squeeze or press.

     The Curie brothers discovered piezoelectricity on quartz crystals. This material is still in use today for precise timing and resonator applications. Quartz is a naturally occurring single-crystal material.

     In 1954 the discovery of Lead Zirconate Titanate (PZT) ceramics led to a family of synthetic materials suitable for many applications. These materials are the most popular choice for ultrasound imaging transducers and arrays.

    What is the Piezoelectric Effect?

  • © 2016 Conquest Imaging

    The most important property of a piezoelectric material is how it can convert electric energy to acoustic energy and vice versa.

    What is the Piezoelectric Effect?

  • © 2016 Conquest Imaging

     Ultrasound transducers used in diagnostic imaging employ an array of piezoelectric elements.

     Each element is wired to allow the application of short high voltage pulses during the transmission of ultrasound waves and the reception of the electronic signal generated during the receive phase.

     The average 2D transducer utilizes 128 piezoelectric elements.

     Diagnostic ultrasound imaging range of frequencies is between 1 to 20 MHz.

    Ultrasound Transducers

  • © 2016 Conquest Imaging

     The higher the frequency of the ultrasound wave, the less it can penetrate, and the lower the frequency, the deeper it can penetrate.

     The higher the frequency, the higher the axial resolution resulting in better image quality.

     The lower the frequency, the lower the axial resolution resulting in lower image quality.

    Ultrasound Transducers

    Probe

    Axial

    Lateral

  • © 2016 Conquest Imaging

    Phased

    Array

    Linear

    Array

    Curved

    Linear

    Array

    Standard Array Formats

  • © 2016 Conquest Imaging

    Linear Probe Piezoelectric Linear Array

    Linear Ultrasound Transducer

  • © 2016 Conquest Imaging

    Phased Array Probe

    Piezoelectric Phased Array

    Phased Array Ultrasound Transducer

  • © 2016 Conquest Imaging

     An ultrasound beam requires focusing during transmit to improve the resolution of the acquired image.

     Transmit focus is done electronically in all modern ultrasound systems.

    Ultrasound Beam Focusing

  • © 2016 Conquest Imaging

    The timing of the transmit pulses to each element is aligned so that the wave fronts from all the piezoelectric elements arrive at a selected spatial point at the same time.

    This is accomplished by introducing a curve into the timing delays, whose center is the desired focal point.

    Electronic focus is the same as using an acoustic lens; however, using electronic instead of physical focus allows the transmit focal point to be changed simply by changing the delay pattern.

    Ultrasound Beam Focusing

  • © 2016 Conquest Imaging

     The wave fronts propagate once they leave the transducer, and there is no way to alter the transmit energy pattern.

     During the receive mode, dramatic enhancement of the focal capabilities of the system can be achieved.

     As the ultrasound wave strikes various interfaces/tissues in the body, some of its energy is transmitted and some is reflected toward the transducer.

    Ultrasound Receive Focusing

    Reflected Energy

    Transducer

  • © 2016 Conquest Imaging

    During the receive phase, an electronic lens is continuously reshaped as the focal point moves away from the array at half the velocity of ultrasound to maintain precise focus along each scan line.

    “Receive Dynamic Focus” maintains superior resolution throughout the ultrasound image, and the resolution is not limited by a small transducer aperture (number of active elements used to generate one scan line) or by a fixed focal zone.

    Receive Dynamic Focus

    Dynamic focus is achieved by controlling the delay of each signal arriving at each element through each channel, such that only signals from the computed sliding focal point arrive at a final summation point at the same time.

  • © 2016 Conquest Imaging

    Dynamic focus is achieved by controlling the delay of each signal arriving at each element through each channel, such that only signals from the computed sliding focal point arrive at a final summation point at the same time.

    Receive Dynamic Focus

  • © 2016 Conquest Imaging

     The ultrasound system applies high voltage pulses to the transducer elements. This produces ultrasound waves that travel through the human body and interact with various organs.

     The reflected energy travels back to the transducer where each of its elements acts as a receiver. The reflected ultrasound energy is converted into tiny electrical signals.

     The ultrasound system processes these signals to produce an image that represents these reflections on the monitor.

    Gray-scale Imaging / 2D Imaging Dynamic Focus

  • © 2016 Conquest Imaging

    When an ultrasound wave travels through a medium, it causes expansion and compression of the medium.

    Ultrasound waves interact with tissue in these five basic manners:

     Transmission

     Reflection

     Scattering

     Attenuation

     Refraction

    Tissue Interactions

  • © 2016 Conquest Imaging

    Transmission: Sound energy transmitted from the transducer enters the body.

    Some of the ultrasound energy continues deeper into the body.

    These waves will reflect from deeper tissue structures.

    Tissue Inter

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