Ultrasound Physics and Instrumentation (Part 1) PDF

3-RAD6124 Ultrasound physics and instrumentation (part 1) Radiological Sciences Department By Dr. Ibrahim Hadadi The evolution of ultrasound technology World War I's naval warfare, Spallanzani's exploration led particularly the destruction Th...

3-RAD6124 Ultrasound physics and instrumentation (part 1) Radiological Sciences Department By Dr. Ibrahim Hadadi 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. Sound waves are characterized by alternating compressions and rarefactions. 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? 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 waves in which the displacement of the medium is in the same direction as the direction of the wave's propagation. 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: Defined by the disturbance of a physical medium. Examples include: Ocean waves Sound waves Seismic waves Electromagnetic Waves (transverse wave): 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: 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. 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 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. Frequency-Period Relationship: The product of frequency and period equals 1 second. Frequency X Period = 1 second 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 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 instrument used.