Ultrasound Physics and Instrumentation Flashcards
7 cards from real CCI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Ultrasound Physics and Instrumentation flashcards as text
The piezoelectric effect in ultrasound transducers refers to:
Answer: Conversion of electrical energy to mechanical vibration and vice versa
Piezoelectric crystals deform mechanically when voltage is applied (transmit) and generate voltage when mechanically deformed by returning echoes (receive).
Increasing the gain on an ultrasound system primarily affects:
Answer: The amplification of returning echo signals
Gain uniformly amplifies all returning echo signals electronically without changing transmission power or depth penetration.
Which Doppler equation component must the sonographer manually align to minimize velocity measurement error?
Answer: Doppler angle (θ)
Velocity = (Doppler shift × c) / (2 × frequency × cos θ); the angle θ must be estimated and corrected by the operator to calculate true velocity.
A spectral Doppler waveform showing systolic flow above and diastolic flow below the baseline in an arterial study most likely indicates:
Answer: Bidirectional flow with forward systole and reverse diastole (triphasic pattern)
A triphasic arterial waveform shows rapid systolic forward flow, brief early diastolic flow reversal, and then slow antegrade late diastolic flow, characteristic of normal peripheral arteries.
The axial resolution of an ultrasound system is best improved by:
Answer: Shortening pulse duration (using higher frequency or damped transducers)
Axial resolution = spatial pulse length / 2; shorter pulses achieved with higher frequencies or heavy damping allow discrimination of closely spaced objects along the beam axis.
In echocardiography, the term 'frame rate' refers to:
Answer: The number of 2D images acquired per second
Frame rate is the number of complete 2D image frames acquired per second and determines the temporal resolution of real-time imaging.
Which bioeffect mechanism is most relevant to diagnostic ultrasound safety concerns at standard clinical intensities?
Answer: Cavitation (both stable and inertial)
Cavitation—oscillation and possible collapse of microbubbles in tissue—is the primary non-thermal bioeffect concern, though significant risk at diagnostic power levels is not established.