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Ultrasound. Spring 2009 Student Final. Ultrasound AKA:. 1)Diagnostic Medical Sonography 2)Sonography 3) 4) Vascular Sonography 5)Echocardiography. Principles of Diagnostic Ultrasound. NON- ionizing Uses high frequency sound waves By giving reflections from parts in the body ?
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Ultrasound Spring 2009 Student Final
Ultrasound AKA: 1)Diagnostic Medical Sonography 2)Sonography 3) 4) Vascular Sonography 5)Echocardiography
Principles of Diagnostic Ultrasound • NON- ionizing • Uses high frequency sound waves • By giving reflections from parts in the body • ? • Cost effective • ? • Can be imaged in sectional, coronal and oblique planes
What makes a good Sonographer? • Knowledge of detailed anatomy and Pathophysiology • 3D anatomy • Good communication • Be able to work under stress
Poor ergonomic habits Poor equipment design Poor posture 80% have muscloskeletal injuries Shoulder (rotator cuff) ? Neck Lower Back Pain ? Eyesight problems Why? Sustained pressure and force ? Assisting with patient movement ? Inadequate work breaks Overall job stress Repetitive Motion Injuries
Still a Neonate • Fairly new technology compared with x-ray • First used for navy sonar in World War II • 1940’s • US waves transmitted and returned
1947 – Through- Transmission • Used to detect tumors and intracranial lesions • With 2 transducers opposite sides of the head • Called through-transmission
Contact Compound Scanner • 1957 • Tom Brown and Ian Donald • Obstetric techniques
Present Day • Smaller machines • Increased resolution • Real time scanning • Portable • Mobile
Properties of Sound Waves • Acoustic waves • Energy that moves back and forth or vibrates at a steady rate • Audible sound waves • 16,000 – 20,000 cycles/sec • Ultrasound waves • 1- 10 million cycles/sec • _____________ mechanical vibrations through a medium • Transmitted by particles of gas, liquid or solid medium
Piezoelectric Effect • AC applied across piezoelectric crystals • Crystals grow an shrink • Conversion of electrical energy to mechanical energy • US is produced from a transducer by this effect
Acoustic Impedance • Has properties similar to light • Focused, refracted, reflected or scattered • Dependent on the density and elastic properties of medium • Velocity of sound • Sound waves are sent and received • Velocity is different among bone, air and soft tissue • Poor impedance in air • Pitch and sound waves are picked up by computer and produce images: based on depths and speeds
Elements of Transducers • Capable of sending and receiving US
Advantages of US • 1. Ultrasound examinations can be non-invasive • 2. Ultrasound methods are relatively inexpensive, quick and convenient • 3. No harmful effects have been detected • 4. Ultrasound is particularly suited to imaging soft tissues
Disadvantages of US • 1. The major disadvantage is that the resolution of images is often limited. • 2. Ultrasound is reflected very strongly on passing from tissue to gas, or vice versa • 3. Ultrasound also does not pass well through bone
Real Time, Dopplerand Color Flow Doppler • Real time: • Multiple rapid image frames per second • Ex: can see pulsative vascular, cardiac structures, diaphragm motion & peristalsis • Doppler • Frequency change in laminar or turbulent flow in vascular structures • Color Doppler • Assigns a color scale to change in frequency • Red toward transducer and blue away from transducer
