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The evolution of ultrasound technology World War I's naval warfare, Spallanzani's exploration led particularly the destruction The medical industry began Dussik published the to the discovery of sound wrought by U-boats,...

The evolution of ultrasound technology World War I's naval warfare, Spallanzani's exploration led particularly the destruction The medical industry began Dussik published the to the discovery of sound wrought by U-boats, experimenting with pioneering study on the beyond the audible spurred the advancement ultrasound for medical ultrasound examination of spectrum. of SONAR technology. purposes. the brain. 1880 1917 Late 1940s 1794 1912 1930s 1942 The Curie brothers, Pierre Utilizing piezoelectric Diagnostic uses for and Jacques, identified the principles, Langevin created ultrasound started to piezoelectric effect, an early ultrasound device. emerge, marking a new era foundational for later in medical imaging. ultrasound technology. The evolution of ultrasound technology Ultrasound technology Institutions worldwide The real-time B-scan expanded with the advent of developed pulsed ultrasound ultrasound was developed three-dimensional (3D) and technology, leading to 'B and introduced in obstetric four-dimensional (4D) Mode' imaging. imaging. imaging. 1956 1980s 1994 1950 1965 1990s Clinical adoption of Advancements made real- Steven Kapral and his team ultrasound commenced in time ultrasound imaging pioneered the use of B-mode Glasgow, paving the way for feasible. ultrasound for brachial plexus broader medical applications. blockade procedures What is sound? Sound is an energy form generated through vibration, a mechanical action that transmits energy from one location to another. It displays as a mechanical or longitudinal wave, requiring a medium—solid, liquid, or gas. Unlike electromagnetic waves, sound cannot propagate through a vacuum. · i Sound waves are characterized by alternating compressions and rarefactions. · Ju Compressions signify an increase in pressure or density, while rarefactions occurs during the troughs of the sound wave, where the vibrating source of the sound wave moves away from the molecules, causing them to become less densely packed. What is sound wave? 9. l, el ji A wave is characterized as a disturbance or fluctuation that transfers energy from one location to another within a medium. This transfer occurs without the need for physical contact between the points. We refer to mechanical waves as longitudinal waves. These are · vsI waves in which the displacement of the medium is in the same direction as the direction of the wave's propagation. · 17 · j in O Wave Formation When a vibration occurs, it disrupts the particles within a medium. This disturbance leads to the - creation of waves that propagate - through the medium - - - Wave Formation All matter, including air, comprises molecules—tiny particles that are interconnected through elastic intermolecular forces. Classification of Waves Mechanical Waves: ~ 1 Defined by the disturbance of a physical medium. Examples include: Ocean waves Sound waves L Seismic waves Electromagnetic Waves (transverse wave): ~2 2 - These waves do not require a medium and can propagate through a vacuum. Examples include: Radio waves X-rays Light ~ longitudinal vs. transverse wave Longitudinal Waves: - Particle displacement occurs parallel to the wave's direction of energy movement. Transmission Mechanics: Requires an initial vibration from a source object. Requires a material for wave travel. The speed depends on the type and state of the medium. Transverse Waves: L Particle displacement occurs perpendicular to the wave's direction of propagation. Transmission Mechanics: Velocity is relatively constant at approximately 299,792.456.2 m/s in a vacuum, which is the speed of light. zu - & d Understanding Parameters in Acoustics Parameters can exhibit Directly Proportional: A parameter is a direct or inverse When one parameter quantifiable factor or proportional decreases, the other also characteristic. relationships. decreases. Inversely Proportional: In Key Parameters of Sound Waves: Important this relationship, a parameters to consider in sound waves include decrease in one parameter results in an Frequency, Period, Wavelength, Propagation increase in the other. Speed, Amplitude, Power, and Intensity Sound Wave Parameters: Frequency Frequency (f): Frequency measures the occurrence rate of an event. In sound, it refers to the number of complete cycles of pressure variation (or any other acoustic variable) in one second. Sound Wave Parameters: Frequency M & - A cycle is a full variation in pressure or another acoustic variable, encompassing both compression (increased density) and rarefaction (decreased density). - -- - Units of Frequency: Measured in hertz (Hz), kilohertz (kHz), and megahertz (MHz), where one hertz is equivalent to one cycle per second, one kilohertz equals 1,000 Hz, and one megahertz is 1,000,000 Hz. Sound Wave Parameters: Frequency Typical Frequency Values in medical The frequency is determined by the ultrasound: Ranging from 2 to 15 MHz. sound source. Y Frequency-Period Relationship: The product of frequency and period equals 1 second. Frequency X Period = 1 second Kov A, Frequency is the number of complete variations (cycles) that an acoustic variable (pressure, in this case) goes through in 1 second. - B, Five cycles occur in 1 second; thus the frequency is five cycles per second, or 5 Hz. C, If five cycles occur within one millionth of a second, also known as a microsecond (1 μs) (i.e., five million cycles occurring in 1 second), the frequency is 5 MHz. Resonance Frequency in Ultrasound Transducers 1650 P - The resonance frequency of an ultrasound transducer is primarily determined by its piezoelectric crystals. Thinner crystals in the transducer vibrate at higher frequencies compared to thicker crystals Frequency plays a crucial role in determining the resolution and penetration of sonographic images. It is adjustable based on the transducer and sonographic s instrument used. Els Sound Wave Parameters: Period - The period value The period is The period is cannot be altered determined by represented by by the the sound source. the symbol (T). - sonographer & Each cycle occurs in 0.2 μs, so the period is 0.2 μs. If one cycle takes 0.2 (or 1⁄5) millionths of a second to occur, it means that five million cycles - occur in 1 second, so the frequency is 5 MHz. Sound Wave Parameters: Wavelength W ① Wavelength (λ) is the length of a cycle in space. m Units for Wavelength: Measured in meters, millimeters, or any standard unit of length. Typical Values in Soft Tissue: Ranges from 0.1 to 0.8 mm. -. Control by Sonographer: The wavelength cannot be modified by the sonographer. - 55% Factors Influencing Wavelength: 1. Transducer Frequency. 2. Speed of Sound in the Medium.  No Sound Wave Parameters: Wavelength Wavelength is calculated as Speed divided by Frequency Wavelength (λ) (mm) = c (mm/μs) ÷ f (MHz) - - - ·- s I. I Wavelength is a crucial parameter that influences the diagnostic quality of M siggBog ultrasound images. Shorter-wavelength sound waves have superior spatial - & resolution but less penetration. - - In this figure, each cycle covers 0.31 mm. Thus the wavelength is 0.31 mm. This figure differs from for a propagation speed of 1.54 mm/μs and a frequency of 5 MHz, the wavelength is 0.31 mm. & Sound Wave Parameters: Propagation speed 561 % E Propagation speed (c) refers to the rate at which a sound wave moves through a medium. & Sus jaS Within a specific medium, sound waves travel at a consistent speed, regardless of their frequency. This means that sound waves at 20 Hz and those at 20 MHz - - - - move at the same speed in the same medium. - The speed of sound wave propagation varies across different mediums. It is generally fastest in solids, like bone, and slowest in gases or gas-containing & - - - structures, such as the lungs - - = - ad T ↓ -  - - G The average propagation speed of sound in tissues & Material speed (m/sec) Air L 330 Fat L 1450 Water W 1480 Soft tissue L 1540 Bone - 4100 Sound Wave Parameters: Amplitude & The amplitude of a sound is created by the number of molecules displaced by a vibration · j g To Amplitude is indicative of the strength or intensity of a sound wave. -a Amplitude is typically measured in units of pressure, such as Mega Pascals (MPa). - - Sound Wave Parameters: Power & O M - : ② Power is the rate at which work is performed or energy is transferred. - In ultrasound, power refers to the generation of ultrasound waves by the - transducer and their propagation through tissues. These waves carry mechanical - energy that facilitates the displacement of particles within the medium. g -I The higher the power, the greater the wave's capacity to perform this work of displacing particles Sist Sound Wave Parameters: Power O The standard unit of power is the Watt (W). > Power in diagnostic ultrasound is commonly expressed in - - milliwatts (mW). One milliwatt equates to one-thousandth of a Watt, meaning there are-1,000 milliwatts in a single Watt. ↳ & 16 %I d  z Sound Wave Parameters: Intensity ~ Intensity (I) is the rate at which energy passes through a unit area. It is equal to the - power in a wave divided by the area (A) over which the power is spread. I Ultrasound is generated by transducers in the form of beams. Beam area is expressed in centimeters squared (cm2). Chil - 6 Intensity units include milliwatts per centimeter squared (mW/cm2) and watts per - centimeter squared (W/cm2). wham mini An increase - in area decreases intensity because power is less concentrated. A - - - decrease in area (focusing) increases intensity because power is more concentrated. - I  - An ultrasound pulse is weakened (reduction of amplitude) as it travels through a medium (in this case from left to right). This weakening is - - called attenuation. - A, Amplitude is the maximum amount of variation that occurs in an acoustic variable (pressure, in this case). In this figure, the amplitude is 2 megapascals (Mpa). ud B, Intensity is the power in a sound wave divided by the area over which the power is spread (the beam area). - Pulsed wave - A pulse, by definition, must have a distinct beginning and end - Pulsed ultrasound comprises two main components: 1. The Cycle: This is the "on" or "transmit" time during which the ultrasound wave is - & > emitted. & - 2. The Dead Time: Also known as the "off" or "receive" time, this is the period during - - - which the transducer awaits the return of the echoes. Pulsed transducers are designed to generate multiple, sequential, short pulses, allowing for the simultaneous - - - use of the same crystal or group of crystals for both sound transmission and echo reception. - => & -  Pulsed wave In pulsed mode, a singular crystal or a specific group of crystals is used for both the transmission of sound and the reception of echoes. -x - S - = - A pulsed transducer emits ultrasound waves that span a variety of - - frequencies. This spectrum is referred to as the 'frequency bandwidth. => - # Pulsed wave transducers are responsible for generating all types of ultrasound diagnostic images, including both-real-time and static. - - &  E95 : Y , > - , - Contentious wave (CW) Cardios15 96 popleur Continuous wave (CW) ultrasound is It is important to note that predominantly employed continuous wave sound is in echocardiography for incapable of creating acquiring CW Doppler anatomic images information.