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Basic Ultrasound Physics

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  1. Section 1

    What is Ultrasound ?
  2. How Are Images Generated ?
  3. Ultrasound Physics Videos
  4. Section 2
    Artifacts
  5. Section 3
    Probe Characteristics
  6. Knobology
  7. Imaging Modes
  8. Section 4
    Scanning & Display Orientation

Quizzes

Basic Ultrasound Physics Probe Characteristics
Lesson 5 of 8
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Probe Characteristics

Outline:

  1. Probe Components
  2. Types of Probes

Probe Components

Ultrasound transducer components

Probe components are as follows:

  1. crystal/ceramic element with piezoelectric properties
    • usually lead zirconate titanate (PZT).
  2. Electrical connection
    • positive and ground elements.
  3. Damping (backing) block
    • This serves to absorb resonant frequencies and is located behind the piezoelectric elements.
  4. Matching layer
    • interface between the transducer element and the tissue, which facillitates transmission of ultrasound from the crytals to the soft tissues with minimal loss of signal strength.
  5. housing
    • electrical insulation and protection of the element

Ultrasound transducers typically consist of 128-512 piezoelectric elements arranged in linear or curvilinear arrays. Beams can be produced linearly (sequential array) or phased array.

Types of Probes

Let’s look at ultrasound probe characteristics. All probes come with an orientation marker, located on one side of the probe. The display monitor has a corresponding marker as well. This allows the user to orientate the probe to the displayed image when scanning.

Commonly used ultrasound probes in point of care ultrasound
Fig 1.18. Image shows the 3 commonly used transducers in POCUS; a) phased array, b) linear array & c) curvilinear array. d) is a transesophageal echo probe.

Ultrasound transducers typically consist of 128-512 piezoelectric elements arranged in linear or curvilinear arrays.

phased array probe
Fig 1.19. Phased Array Probe

Characteristics: Small footprint, low frequency (1-5MHz), high frame rate. Ideal for scanning between the ribs. High frame rate allows scanning of moving structures.

linear probe
Fig 1.20. Linear Probe

Characteristics: High frequency (5-13MHz), ultrasound waves emitted in straight line. Image displayed in rectangular field. Ideal for high resolution imaging at shallow depth. Lung pleura, blood vessels, nerves & US guided procedures.

curvilinear probe
Fig 1.21 Curvilinear Probe

Low frequency probe used for imaging deeper structures such as lung parenchyma, abdominal ultrasound and OBGYN scans. Lower ultrasound frequencies have better penetration.