Ch 14 Flashcards
Transducer
Converts electrical to acoustic energy (transmission) Converts acoustic to electrical energy (reception)
Master Synchronizer
Communicates organizes and times the functions
Pulser
determines the amplitude, PRP, and PRF occurs during transmission creates and controls electrical signal sent to transducer
Beam Former
determines the firing, delay patterns for phased array system
Receiver
transform electrical signals from the transducer into a form suitable for display
Display
Monitor
Storage
archives the ultrasound studies storage devices include: computer hard drives, CD, DVD, videotape, magneto-optical discs, paper printouts, photographs, and USB
Transducer output
effects entire image use during transmission can cause exposure/ bioeffects Adjustable
Transducer Synonyms
output gain, acoustic power, pulser power, energy output, transmitter output, power or gain
Noise
random and persistent disturbance that obscures or reduces a signal’s clarity
Signal to Noise when high
signal is much stronger than the noise and the image is a high quality
Signal to Noise when low
degrades image strength is closer to strength of the noise
Signal to Noise
comparison of the meaningful info (signal) to the amount of contamination (noise)
increase output power, signal to noise ratio ______.
increase
PRP and PRF are what related
inversely
Is PRP adjustable
Yes
Shallow Imaging listening time PRP PRF
shorter listening time shorter PRP higher PRF
Deep Imaging listening time PRP PRF
longer listening time longer PRP lower PRF
Apodization
adjust electrical spikes voltage to reduce love artifacts
Order of Receiver Operations
- Amplification 2. Compensation 3. Compression 4. Demodulation 5. Reject
Amplification adjustable? singals processed Effects on image
adjustable all signals trated identically entire image gets brighter or darker
Compensation adjustable? singals processed Effects on image
adjustble signals treated differently based on reflector depth image will be uniformly bright from top to bottom
Compression adjustable? singals processed Effects on image
adjustable signals treated differently depending on strength changes gray scale mapping
Demodulation adjustable? singals processed Effects on image
not adjustable prepares electrical signals to be suitable for display none
Reject adjustable? singals processed Effects on image
adjustable only weak signals affects; strong signals remain unchanged weal echoes appear or are eliminated from image
Dynamic Frequency Tuning
uses damping material to create short pulses, which provides better axial resolution use only high frequencies
ALARA
As Low As Reasonably Achievable minimizes the patients ultrasound exposure
Output Power vs Receiver Gain Output Power
changes brightness of entire image alters signal to noise ratio alters patient exposure bioeffect concerns decrease this first if image is too bright
Output Power vs Receiver Gain Receiver Gain
changes brightness of entire image doesn’t affect signal to noise ratio doesn’t change patient exposure no bio effect concern increase this first if image is too dark
