2. What is Sound
• Mechanical Longitudinal Wave Generated by objects vibration that travel in a
medium (like: air, water) cause compression and expansion (Rarefactions) the
particles (pressure).
• Waves have an amplitude (volume) frequency (pitch), wavelength (speed)
• Sound travel in air with average speed 345 m/s
• Sound travel through steel 5,200 m/s
4. What is Sound
• Human hearing range 20-20,000 Hz (upper limit decreases by age)
• Bat, Dolphin up o 160,000 Hz
5. Medical Ultrasound
• Diagnostic ultrasound is a non-invasive diagnostic technique used to
image inside the body.
• Pros/ advantages:
• Safe (especially in obstetric)
• No pre-operate procedure requirements
• Diagnose wide range diseases with high success rate.
• Direct visualization
• Cons/ disadvantages:
• Trained staff
• Not always efficient with deep tissues
6. Medical Ultrasound
• Thyroid and parathyroid glands.
• Scrotum (testicles)
• Infants (brain, Spine, hips)
• Heart and blood vessels
(cardiovascular system)
• Liver and gallbladder
• Spleen
• Pancreas
• Kidneys and Bladder
• Uterus, Ovaries
• Obstetrics Unborn child (fetus) in
pregnant patients
• Eyes
7. Medical Ultrasound
• Diagnostic ultrasound range (2 MHz to 20 MHz)
• 2.5 MHz: deep abdomen, obstetric and gynecological imaging
• 3.5 MHz: general abdomen, obstetric and gynecological imaging
• 5.0 MHz: vascular, breast, pelvic imaging
• 7.5 MHz: breast, thyroid
• 10.0 MHz: breast, thyroid, superficial veins, superficial masses,
musculoskeletal imaging.
• 15.0 MHz: superficial structures, musculoskeletal imaging.
8.
9. Ultrasound Transducer
Ultrasonic waves are both generated and detected by a piezoelectric
crystal. These crystals deform under the influence of an electric field and,
vice versa, induce an electric field over the crystal upon deformation. As a
consequence, when an alternating voltage is applied over the crystal, a
compression wave with the same frequency is generated. A device
converting one form of energy into another form (in this case electric to
mechanical energy) is called a transducer.
13. Ultrasound Transducer
• Attenuation: Attenuation refers to the loss of acoustic energy of the
ultrasonic wave during propagation. In tissues, attenuation is mainly
due to the conversion of acoustic energy into heat because of
viscosity.
