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physical ultrasound

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  1. Al-Quds university Graduate School Ultrasound Radwan Al-qasrawi Arwa Badarin

  2. Contact • Introduction • Ultrasound tissue interaction • Compound of ultrasounds • Image formation • Image display • Application of ultrasound

  3. Sound •Sound is a mechanical, longitudinal wave that trave a straight line • Sound waves are transmitted as a series of alternating pressure waves with high pressure and low pressure pulses. •The high pressure areas (compression) are where the particles have been squeezed together; the low pressure areas (rarefaction) are where the particles have been spread apart. • Sound waves cannot travel in vaccum

  4. CHARACTERISTICS OF SOUND • A sound beam is similar to x-ray beam in that both are waves transmitting energy but important difference is that x-rays pass through a vacuum where as sound require a material medium ( solid, liquid , gas ) for transmission, they will not pass through the vacuum. • Sound must be generated mechanically by vibrating body matter

  5. History •Piezoelectricity discovered by Pierre and Jacques Curie in 1880 using natural quartz • SONAR was first used in 1940s war time • Diagnostic medical applications in use since late 1950's

  6. "Ultra".......sound? Ultrasound imaging is a medical imaging technique It uses high-frequency sound waves to create images of internal body structures It is safe, painless, and non-invasive Audible range is 20 to 20,000 cycles per second • Ultrasound has frequency greater than 20,000 cycles per second

  7. Ultrasound tissue interaction : 1. Reflection 2. Refraction 3. Absorption 4. Attenuation 5. Scattering

  8. Compound of ultrasounds : 1-transducer :that produces and receives sound waves, 2-CPU:a processing unit that generates images 3-display:a display to view the images 4.control panel to adjust settings 5- power supply 6- printer: prints the image from the displayed data

  9. How is ultrasound imaging done? "From sound to image"

  10. The Transducer Converts electrical energy into sound • Components: Piezoelectric crystal • Dampening material • Matching layer covers crystals Electrodes

  11. ACOUSTIC IMPEDANCE • The ratio of the pressure over an imaginary surface in a sound wave to the rate of particle flow across the surface. • It's the fundamental properties of matter. Z= p V Z = acoustic impedance p = density V = velocity of sound

  12. How is an image formed on the monitor? • The amplitude of each reflected wave is represented by a dot • The position of the dot represents the depth from which the echo is received • The brightness of the dot represents the strength of the returning echo • These dots are combined to form a complete image

  13. Position of Reflected Echoes Position of Reflected Echoes • How does the system know the depth of the reflection? • TIMING - The system calculates how long it takes for the echo to return to the transducer - The velocity in tissue is assumed constant at 1540m/sec Velocity = Distance x Time/2 Reflected Echoes • Strong Reflections = White dots - Pericardium, calcified structures, diaphragm • Weaker Reflections = Grey dots - Myocardium, valve tissue, vessel walls, liver • No Reflections = Black dots - Intra-cardiac cavities, gall bladder

  14. The reflected signal can be displayed in four modes A-mode displays the depth of structures based on amplitude. B-mode displays a 2D cross-sectional imag. M-mode displays motion over time. 2D mode provides real-time 2D imaging.

  15. Application of ultrasound 1-Obstetrics and Gynecology: used during pregnancy to monitor fetal development and check for any abnormalities 2-Cardiology: which can be used to diagnose conditions such as heart valve disease, heart failure 3-Radiology: used to create images of various organs and tissues in the body, including the liver, kidneys 4-Vascular medicine: used to diagnose and monitor conditions affecting the blood vessels, such as deep vein thrombosis

  16. Thank you

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