WEEK 10 (Ultrasound) Flashcards
What are the characteristics of Sound waves?
- longitudinal waves
- compressions and rarefactions are moving
- local oscillation of pressure occurs
What are the functions of ultrasound?
- used in medicine for diagnosing and therapy
- helps measure distance and velocity
What are the characteristics of ultrasound?
- non-invasive
- good visualisation characteristics
- relatively easy management
What is used to measure distance and velocity using ultrasound?
ECHO is used to measure distance
DOPPLER EFFECT is used to measure velocity
What are the two techniques used in diagnostic ultrasound?
TRANSMISSION & REFLECTION
What is the difference between Transmission and Reflection?
TRANSMISSION distinguishes tissues by different absorbance of ultrasound currently abandoned
REFLECTION registers the pulse reflected from the boundary of two tissues with different acoustic resistance
What is the function of Lithotripsy?
To treat stones in the kidney, gallbladder and liver
What is the function of the Cavitron ultrasonic surgical aspirator?
Destroys and removes brain tumours
What is the Piezoelectric effect?
Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress.
What is the Piezoelectric effect?
Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress.
What are the four modes that diagnostic ultrasound imaging uses?
- A mode
- B mode
- M mode
- Doppler mode
Describe the B Mode “Brightness modulation”/2D of A mode
- Linear array of transducers simultaneously scan a plane through the body and image is viewed as 2D image on screen
- Generally used to measure cardiac chamber dimensions, access structure of valves and function
Describe the M mode or “Movement mode”
- A rapid sequence of B-mode scans whose images follow each other in sequence on screen enables doctors to see and measure range of motion as the organ boundaries that produce reflections move relative to the probe
- Represents movement of structures
- Generally used to measure chamber dimensions
Describe the Doppler mode
- Continuous wave or spectral doppler image
- Uses different piezo crystals for sending and receiving ultrasound
- Waveform of velocities - allows to distinguish arteries and veins
What are the three different types of Doppler mode?
- Power doppler
- Color doppler
- Pulse wave doppler