Ultrasound (sonography) is a noninvasive diagnostic technique that uses high-frequency sound waves to capture real-time images and videos inside the body. It operates without ionizing radiation and is highly effective for evaluating soft tissues, organs, and dynamic movements like blood flow
How Ultrasound Works
Diagnostic ultrasound typically uses sound frequencies between 2 and 15 megahertz (MHz), which are well above the threshold of human hearing. The process relies on a few key components:
- Transducer (Probe): A handheld device placed directly on the skin (or inserted into body openings) that emits short pulses of sound waves into the body.
- Gel: A thin layer of gel applied to the skin eliminates air pockets, allowing the sound waves to travel smoothly into your tissue.
- Echoes: As the sound waves pass through the body, they bounce back as echoes whenever they hit a boundary between different tissues (e.g., fluid vs. soft tissue or bone).
- Computer Processing: The transducer captures these returning echoes, and a computer calculates how far the wave travelled and its strength to map out a live, visual image on a monitor.
Key Uses and Capabilities
Images are captured live, and they produce moving views of internal structures:
- Structural Imaging: Doctors use it to visualise organs like the liver, kidneys, uterus, and heart.
- Real-Time Motion: Tracks dynamic events, such as a beating heart, heart-valve motion, or a developing fetus during an obstetric scan.
- Blood Flow (Doppler Ultrasound): By measuring the shift in frequency of the returning echoes (the Doppler effect), sonography can visualise the velocity and direction of blood cells moving through your vessels.
- Procedure guidance/management: It provides safe, real-time tracking for medical professionals performing biopsies or fluid drainage.