Ultrasound Flashcards
Depth knob for ultrasound
As deep as needed for area of interest- if you are looking for vessels don’t want depth to go to bone
Gain knob for ultrasound
Amplification of the returning echoes.. should not generally need to change this a lot (makes images brighter or darker)
Time Gain Compensation knob for ultrasound
Changes amplification based on return time of echoes and compensates for attenuation of the ultrasound as it passes through tissue
Auto-optimize knob for ultrasound
Automatic control that adjusts gain
Focus knob for ultrasound
If entire image is important you- put it at the bottom, put focus at area of interest
Frequency knob for ultrasound
Highest possible that allows for penetration-high frequency has better resolution but less penetration, low frequency has less resolution but higher penetration
Freeze button for ultrasound
Freezes the image for a limited about of time
Store Image button for ultrasound
Patient data must be on image and then is stored to the hard drive on the machine and then moved to long term storage
Doppler shift defined
Change in reflected frequency compared to frequency sent out when there is motion between source & reflector
What will you see with vessels & doppler shift
If blood is moving TOWARD transducer- instrument displays red and is considered positive shift, blood moving away it’s considered negative shift and displays blue regardless of arterial or venous– this is due to frequency- toward moves at higher frequency (more waves/second)
Rules about doppler imaging
Must angle beam to be more parallel to the vessel (not 90 degrees), turn gain up & scale down if you can’t identify flow, identify which vessel is vein & artery
Transverse plane of scanning
Whatever probe is closest to will see that at top of screen- it’s a slice cutting in half the top from the bottom– considered off axis
Longitudinal plane of scanning
Divide body into section- long axis
Indicator on transducer
The little knob, groove or colored dot on the probe
Indicator & screen orientation
SHOULD be on left side of the screen
Will lateral/medial or superior/inferior show up with off axis
This is transverse- it will be lateral and medial
Will lateral/medial or superior/inferior show up with on axis
This is longitudinal- it will be superior and inferior
In axis, in plane
Longitudinal of anatomy, needle will be in plane of view
Off axis off plane
Transverse of anatomy, needle will be out of plane but will see little dot on screen maybe
Off axis in plane
Most popular for regional, will see transverse of anatomy but needle will be in plane
Indicator & needle
Should have needle entering on side of indicator so it comes in on left side of the screen
Echogenic
Has echoes- white
Anechoic
Without echoes, black
Hyperechoic
Having more echoes when compared to adjacent structure
Hypoechoic
Having less echoes when compared to adjacent structure
Isoechoic
Same echoes when compared to adjacent structure
What color does fluid appear to be?
Anechoic
Acoustic shadow
When structures deep to an object are missing, due to high attenuation of US by dense structures
Pulse-echo technique
US sent into body, it reflects off structures and returns to the transducer. Each pulse produces one line of information
With pulsed ultrasound what does the instrument assume
US went straight through body, reflected off different structures, reflections traveled straight back to transducer and that this path only happened once
Reflections in ultrasound
Occur when there is a change in impedance of the medium, there are specular and non-specular
Specular Reflections
From smooth surfaces- diaphragm, vessel walls, nerves- should image them perpendicular
Reverberation
US beam makes the path more than once, extra echoes on the image that do not represent true anatomy
