1 / 16

ULTRASONOGRAPHY

ULTRASONOGRAPHY. What is Ultrasound?. High frequency, inaudible sound waves of 1-10 MHz Audible frequency is 20-20,000 Hz Reflection of ultrasound occurs between substances of different acoustic impedance Product of velocity of sound and density of substance

sweets
Download Presentation

ULTRASONOGRAPHY

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ULTRASONOGRAPHY

  2. What is Ultrasound? • High frequency, inaudible sound waves of 1-10 MHz • Audible frequency is 20-20,000 Hz • Reflection of ultrasound occurs between substances of different acoustic impedance • Product of velocity of sound and density of substance • Ultrasound waves unable to pass through vacuum and transmission in air is poor

  3. Ultrasound • Ultrasound uses high frequency sound waves and their echoes. • The ultrasound machine transmits high-frequency sound pulses. • The sound waves hit a boundary between tissues (e.g. between fluid and soft tissue, soft tissue and bone). • Some of the sound waves get reflected back to the probe, while some travel on further until they reach another boundary and get reflected.

  4. Principle of Ultrasound Electricity Transducer U/S waves Scan converter Transducer Tissue Cathode tube Image of Object

  5. Ultrasound • Transducer sends and receives high frequency sound waves • Transducer must be in contact with structure being examined • Ultrasound gel or obstetric lube used to make contact complete.

  6. How ultrasounds generated and detected? • High voltage to piezoelectric crystals generates waves of specific frequency • Higher the frequency, better the details (better differentiation), but poor penetration (depth) • Lower the frequency, poorer the details, better penetration

  7. Wave length • Higher frequency = shorter wavelength • Shorter wavelength = better resolution • Better resolution = view smaller objects with more detail • Shorter wavelength = less penetration • Less penetration = view objects close to surface • Rectal exams 5 MHz transducer

  8. Wave length • Lower frequency = Longer wavelength • Longer wavelength = less resolution • Less resolution = less detail • Longer wavelength = more penetration • More penetration = view deeper objects • Transabdominal 3 MHz transducer

  9. 7 mHz 5mHz 3mHz

  10. Transducers • Crystals vibrate at high frequency producing sound waves • The sound waves are transmitted and received by the transducer • The transducer is identified by the crystal array. • The array is the way in which the crystals are arranged • Linear array • Convex array

  11. Transducers • Piezoelectric material, Lead Zirconate Titanium • Frequency of 1 to 10 MHz is used • Linear transducers • 64-256 no of crystals • Sealed to avoid moisture

  12. Linear array

  13. Convex Array

  14. Sound wave reflection

  15. How is interpretation done? • Anechoic Black (Fluids) • Hypoechoic Grey (Soft Tissue) • Hyperechoic White (Bones)

  16. Ultrasound Wave Transmission Transducer Sends and receives ultrasound waves WATER SOFT TISSUE BONE /AIR/ METAL

More Related