Ultrasound Adams Flashcards
Frequency
Number of cycles per second
Hertz
Wavelength
The length of one complete cycle
If you increase frequency, what happens to wavelength?
Decreases
The part of the ultrasound you lay against a persons skin is called what?
Footprint
SPL
Voice of the ultrasound machine
Spatial pulse length..3 bursts
This is only 1 % of the ultrasound time (most the time its listening)
Axial
How deep US goes
Lateral
How wide US goes
If wavelength decreases, what happens to SPL?
Decreases
So you have more listening time!
Why don’t we use something with a really short frequency all the time if it provides the best resolution?
LESS PENETRATION
Ex. dolphin clicks underwater dissipate quickly whereas a whales low pitched sound lasts for longer
High density in body
Ultrasound travels BETTER through high density
Ex. much better through water than air…hence we do a full bladder for pelvic ultrasounds
Flexibility…Good or bad transmission?
GOOD!
Liver is great
Bone is NOT..everything gets reflected
2 types of scanning formats
Linear (usually used for high frequency)–rectangular probe
Penetrate 2-4 inches (very superficial)–would use this to put a central line in
sector (more of a flashlight sort of beam..the farther down you go the less accurate because beams spread out)
Classic probe for sector array
Curvilinear array transducer
Square transducer to see the heart
Phased array transducer
*sector array but allows you to see the heart between the ribs
Gain
the amount of amplification added to the signal coming from the transducer to the screen
- Machine allows deeper stuff to be brightened up
- you can adjust gain on the machine..if screen image is too bright, turn gain down
Example of medium gray scale
Liver
Example of low gray scale
Bladder
*Anechoic–black because fluid filled…US goes right through water
High gray scale example
Gall bladder stone–hyperechoic…leaves a shadow since most of the US waves have been reflexted
2 types of image formatting
B mode–real time
M mode
B mode
Use this for FAST exam…most common…real time
What is M mode and why would you use it?
Looks at one spot over time…example to look at heart valve opening and closing
Colors of kidney on US
white border
Black center that is Kind of nougat
COLOR OF FLUID ON US
BLACK
Ultrasound gel: use a lot or a little?
A lot! Replenish frequently
2 rules of US orientation
The top of the viewing screen is ALWAYS where the transducer is touching the patient
The orientation marker on the transducer and on the viewing screen ALWAYS point in the same direction
*Classically green dot on left side of screen (so if you move the probe the screen moves the same direction)
*Try to keep probe at what degree to the skin?
90 degrees
Red color
Blood flow TOWARDS transducer
Blue color
Anything going AWAY from transducer
What is FAST exam for?
Focused rapid exam looking for fluid/blood in abdomen
Standard of care for appendicitis imaging?
Ultrasound!
Not CT
