Medical Ultrasound Techniques

History and Definition

• Ultrasound uses high-frequency sound for medical diagnosis and treatment.
• It was discovered in the 1880s.
• Ultrasound frequencies are above the upper limit of human hearing (20,000 Hz).

Piezoelectric Effect

• The piezoelectric crystal, used in transducers, converts electrical current into ultrasound waves and vice versa.

Pulse-Echo Principle

• Ultrasound waves are generated and sent into tissues.
• Waves interact with tissues, generating echoes.
• Echoes are received back by the transducer.
• The transducer converts echoes into image data.

Ultrasound Frequencies

• Common frequencies used in medical imaging: 2 - 20 MHz.
• Lower frequencies penetrate deeper into the body.
• Higher frequencies provide better resolution and image detail.

Transducers

• Frequencies vary depending on clinical use:
  • 2.5 MHz: Deep abdomen.
  • 3.5 MHz: General abdominal and pelvic imaging.
  • 5.5 MHz: Vascular imaging.
  • 7.5 MHz: Breast and thyroid imaging.
  • 10 MHz: Superficial musculoskeletal imaging.

Ultrasound Knobology and Settings

• Power Button: Turns the ultrasound machine on.
• Probe Selection: Choose the appropriate transducer for the desired imaging area.
• Application Preset: Sets default parameters for specific imaging applications (e.g., abdomen, breast).
• Depth: Determines the section of the body being imaged.
• Gain (Overall): Amplifies the strength of the ultrasound signal.
• Near/Far Field Gain & Time Gain Compensation (TGC): Adjusts amplification of the signal at different depths to compensate for attenuation.
• Focus: Sharpens the image by focusing the ultrasound beam at a specific depth.

Ultrasound Modes

• B-mode (Brightness Mode): Displays structural information using different shades of grey.
• M-mode (Motion Mode): Captures echoes along a single line and displays them over time, showing movement.

This quiz covers the fundamental concepts of medical ultrasound, including its history, the piezoelectric effect, and the pulse-echo principle. Learn about the different frequencies used in ultrasound imaging and their clinical applications.