Introductory Lectureb
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Oct 11, 2024 02:27 PM
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Outline
OutlineIntroduction to Ultrasound (US) Reading ListParametersPropagation of US waves in tissue ？Attenuation
Introduction to Ultrasound (US)
Reading List
Peter Hoskins, Kevin Martin, Abigail Thrush - “Diagnostic Ultrasound, Third Edition: Physics and
Equipment” (2019) CRC Press; 3rd edition (20 May 2019) – available as a digital copy via Dundee
Library
Nadine Barrie Smith, Andrew Webb -“Introduction to medical imaging: physics, engineering and
clinical applications” (2010) Cambridge University Press – chapter on Ultrasound - available as a
digital copy via Dundee Library
Parameters
Diagnostic Ultrasound (i.e. imaging/sensing) frequencies: 𝑓 1 – 20 MHz (most
common)
Average speed of sound in tissue: 𝑐 ~1540 𝑚/𝑠
US waves: 𝑐 = 𝜆𝑓 (equation valid for any wave phenomenon) gives wavelengths
in the range 0.1 – 1.5 mm.
Period: T = 1/𝑓
(Acoustic) media are characterized by three physical quantities: mass density 𝝆, speed of sound c and compressibility 𝑘 though the equation:
𝐵 = 1/𝑘 is known as the bulk modulus/stiffness.
, is
Using the SI definition of 1 Pascal (Pa) as 1 , which is equivalent to 10 , the units of compressibility are the same as inverse pressure.
, acoustic characteristic impedance, 声学特性阻抗
Propagation of US waves in tissue ？
fat - liver interface represents that is liver, is fat.
Attenuation
while , , hence
→ = 15.85, 10/15.85=0.631
两种方法
