Ultrasound Physics Fundamentals

Producing a sound wave:  Ultrasound waves are produced by a transducer. A transducer is a device that takes power from one source and converts the energy into another form eg electricity into sound waves. The sound waves begin with the mechanical movement (oscillations) of a crystal that has been excited by electrical pulses, this is called the piezoelectric effect.The sound waves are emitted from the crystal similar to sound waves being emitted from a loud speaker. The frequencies emitted are in the range of (2- 15MHz) and are unable to be heard by the human ear. Several crystals are arranged together to form a transducer. It is from the transducer that sound waves propagate through tissue to be reflected and returned as echoes back to the transducer.

 Sound is produced using Piezoelectricity which is the ability of some materials (notably crystals and certain ceramics) to generate an electric charge in response to applied mechanical stress, the reverse applies when the word is derived from the piezoelectric effect is reversible in that materials exhibiting the direct piezoelectric effectconverse piezoelectric effect (the production of stress and/or crystals will exhibit a maximum shape change of about 0.1% of the original dimension.

Precise electrical pulses from the ultrasound machine make the transducer create sound waves at the desired frequency. The sound is focused either by the shape of the transducer (Curved, Linear, Sector) or a set of control pulses from the ultrasound machine. This focusing produces the desired shaped sound wave from the face of the transducer. The wave travels into the body and comes into focus at a desired depth. On the face of the transducer a rubber material enables the sound to be transmitted efficiently into the body. This rubber coating is required for impedance matching and allows good energy transfer from transducer to patient a vice versa. To help with the transmission of sound waves a water based gel is placed between the patient’s skin and the probe.The gel establishes good acoustic contact with the body, since air is a very good acoustic reflector.

Some Videos:

Physics of Diagnostic Ultrasound – Segment # 1

Physics of Diagnostic Ultrasound – Segment # 2

Physics of Diagnostic Ultrasound – Segment # 3

Physics of Diagnostic Ultrasound – Segment # 4

Ruling Out Myocardial Ischemia in Low Risk Chest Pain Patien

Physics of Ultrasound: Transducers – Segment #1

Physics of Ultrasound: Transducers – Segment #2

Physics of Ultrasound: Transducers – Segment #3

Physics of Ultrasound: Transducers – Segment #4

Physics of Ultrasound: Transducers – Segment #5

Physics of Ultrasound: Transducers – Segment #6

Physics of Ultrasound: Pulse Echo US – Segment #1

Physics of Ultrasound: Pulse Echo US – Segment #2

Physics of Ultrasound: Pulse Echo US – Segment #3

Physics of Ultrasound: Pulse Echo US – Segment #4

Physics of Ultrasound: Pulse Echo US – Segment #5

Physics of Ultrasound: Image Artifacts – Segment #1

Physics of Ultrasound: Image Artifacts Segment #2

Physics of Ultrasound – Image Artifacts NEW Segment #2

Physics of Ultrasound: Image Artifacts Segment #3

Physics of Ultrasound – Image Artifacts NEW Segment #3

Physics of Ultrasound: Image Artifacts Segment #4

Physics of Ultrasound: Image Artifacts Segment #5

Physics of Ultrasound: Image Artifacts Segment #6

Image and Storage Display – Segment #1

Image Storage and Display – Segment #2

Image Storage and Display – Segment #3

Image Storage and Display – Segment #4

Image Storage and Display – Segment #5

Image Storage and Display – Segment #6

Quality Assurance of Medical Ultrasound Systems – Segment #1

Quality Assurance of Medical Ultrasound Systems – Segment #2

Quality Assurance of Medical Ultrasound Systems – Segment #3

Bioeffects and Safety of Diagnostic Ultrasound – Segment #1

Bioeffects and Safety of Diagnostic Ultrasound – Segment #2

Hemodynamics (Bonus Lecture pre-Doppler)

Doppler Lecture: Segment#1

Doppler Instrumentation and Color Doppler – Segment #2

Doppler Instrumentation and Color Doppler – Segment #3

CCUS (Critical Care Ultrasound Skills Session) -Video1.wmv

Tutorial:

Tutorial 1 – Basic physics of ultrasound and the Doppler phenomenon

Tutorial 2 – Modes of Ultrasound

Tutorial 3 – Setting up and acquiring images

Tutorial 4 – Volume status and preload responsiveness assessment

Tutorial 5 – Assessment of LV systolic function

Tutorial 6 – Assessment of LV diastolic function and filling pressures

Tutorial 7 – Assessment of the right heart

Tutorial 8 – Assessment of pericardial disease

Tutorial 9 – Lung ultrasound

Tutorial 10 – Vascular ultrasound

Tutorial 11 – Abdominal ultrasound

Tutorial 12 – Miscellaneous uses

Tutorial 13 – Clinical scenarios

Tutorial 14 – Infection control and legal issues

Posted on مارس 29, 2012, in English, کل مطالب, اطلس پزشکی. Bookmark the permalink. 3 دیدگاه.

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