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
What are the characteristics of the Power doppler?
- 5 times more sensitive than color doppler
- Used to evaluate blood flow velocity through vessels of different organs
What are the characteristics of the Color doppler?
- Red and blue display
- Provides information regarding direction and velocity of flow
What are the characteristics of Pulse wave doppler?
- Emits short pulses of ultrasound
- Uses same crystal for sending and receiving ultrasound
Upper part of an image on the screen is _______ to the probe
Lower part of an image on the screen is _________ to the probe
Near
Further
What are the different ultrasound probe positions?
- Longitudinal probe position
- Transverse probe position
- Coronal probe position
What are the differences between Axial resolution and Lateral resolution?
AXIAL RESOLUTION increases with narrowing bandwidth
LATERAL RESOLUTION increases with higher frequencies
Superficial structures require __________ frequencies
Higher
Deeper organs require ___________ frequencies
Lower
What are the different diagnostic ultrasounds?
- ABDOMINAL ULTRASOUND
- VASCULAR ULTRASOUND
- OBSTETRIC ULTRASOUND
- GYNAECOLOGICAL ULTRASOUND
- NEUROSONOGRAPHY
- ECHOCARDIOGRAPHY
- OPTHALMOGIC ULTRASOUD
What are the different diagnostic ultrasounds?
- ABDOMINAL ULTRASOUND
- VASCULAR ULTRASOUND
- OBSTETRIC ULTRASOUND
- GYNAECOLOGICAL ULTRASOUND
- NEUROSONOGRAPHY
- ECHOCARDIOGRAPHY
- OPTHALMOGIC ULTRASOUD
What are the therapeutic applications of Ultrasound?
- used to generate regional heating and mechanical changes in biological tissue
- breaking up of kidney stones by LITHOTRIPSY
- cataract treatment
- FUS (FOCUSED ULTRASOUND SURGERY) or HIFU (HIGH INTENSITY FOCUSED ULTRASOUND) can be used to generate highly organised heating to treat cysts and tumors
- clean teeth in dental hygiene
What is Cavitation?
Formation of vapour cavities and bubbles due to the force action on liquid
Cavitation is similar to boiling. When does the Liquid to Gas phase transition occur in boiling and cavitation?
BOILING - occurs if temperature of liquid reaches saturation temperature and pressure of saturated vapour becomes equal of local pressure
CAVITATION - local pressure becomes lower than pressure of saturated vapour at given temperature
