Knobology Flashcards
What is the pathway to which Echo Images are made?
- Electrical Voltage applied to crystals in the probe
- Crystals (probe) vibrate
- Vibration –> Sound pulses Made
- TEE sends out the ultrasound sound pulses
- Pulses bounce off of objects and reflect back (Echo)
- Returning echos cause 2nd vibration in crystals
- Vibrating crystals create an electrical voltage difference
- Voltage difference is used to create an image
- Image displayed on the screen
What is A mode?
Amplitude Mode
(Not used anymore but strength of echo was plotted as amplitue)
What is B-Mode?
Brightness Mode
What is M-Mode?
Motion Mode
What is 2-D grayscale imaging?
Multiple M-modes to create 2D images
What are the axis of M-mode?
X-axis = Time
Y-axis = Depth
What is the frame rate of M-Mode?
1000
What does Brightness in M-Mode reflect?
Strength
What is seen here at the Aortic Valve in M-Mode?
HOCM
- Early closure of aortic valve leaflets
- Below is another image of this
What is a 2D: Phased array?
Multiple Scan Lines
- M-Mode of an entire scan plane
Multiple Pulses frorm multiple crystals
Real 2D images on the Screen
What is the basics of ultrasound physics when referring to Sound (Wave) and Medium?
Sound = Mechanical Longitudnal Wave
- Sound waves are compressions and rarefraacations in the molecules in the medium
Medium = Vibrates left/right as sound travels L –> R
What type of wave is Sound Not? (Odd question, but often confused)
Sound is NOT a Transverse Wave (it is a longitudinal wave)
What is the velocity of sound in media?
1540 meters/sec
What is a sound wave by definition?
Compression and Rarefactions in the molecules in the medium
Rarefactions* are areas of ultrasound wave having low pressure as the distance of their particles is far while *compressions are areas having high pressure as the distance of their particles is close.
What is the period in terms of ultrasound waves?
The amount of time it takes to complete a single cycle (Single wavelength time period).
What is frequency in terms of wave properties?
The number of cycles per second
What is frequency in relationship to period in terms of ultrasound waves?
1/Period = Frequency
What is pulse duration?
The amount of time it takes to complete an entire pulse
(Period of time it takes to complete pulse cycle)
What is pulse repetition period?
Period between pulses including listening time (Blank space)
(Includes pulse duration and listening time)
What is the pulse repetition frequency?
The inverse of the pulse repetition period
AKA the number of pulses per second
(# of pulses per second)
Why is PRF important (Pulse repetition frequency) important?
*2 reasons*
- Determines temporal resolution
- Determine nyquist limit
What is the max doppler shift?
What is the max doppler shift if how it relates to pulse repetition Frequency (PFR)?
Max Doppler Shift = Nyquist Limit
1/2 (50%) of the Pulse Repitition Frequency