Basic Principles of Ultrasound Exam Flashcards
If amplitude is double, intensity is ____
a. doubled
b. unchanged
c. halved
d. quadrupled
d. quadrupled
A unit for intensity is ____
a. cm/MHz
b. mW/cm2
c. mHz/cm2
d. mm/cm2
b. mW/cm2
Because diagnostic ultrasound pulses are usually two or three cycles long, axial resolution is usually equal to ____ to ____ wavelengths.
a. 4,6
b. 1, 3.5
c. 1, 1.5
d. 2, 3
c. 1, 1.5
With perpendicular incidence, the reflected intensity depends on the ____.
a. density difference
b. impedance difference
c. impedance sum
d. b and c
e. a and b
d. b and c
Induced acoustic-emission effects are independent of:
a. Doppler shifts
b. microbubble size
c. contrast motion
d. all of the above
c. contrast motion
SPL is the ____ of _____ that a pulse occupies while it travels
a. amount, amplitude
b. length, space
c. length, time
d. intensity, energy
b. length, space
In harmonic-imaging mode, the echoes from the oscillating microbubbles have a:
a. low singal-to noise ratio
b. low transducer frequency
c. equal signal-to-noise ration
d. high signal-to noise ratio
d. high signal-to noise ratio
Sound travels most slowly in _____
a. liquids
b. gases
c. bone
d. tissue
b. gases
If the intensity of 40-MHz ultrasound entering soft tissue is 2 W/cm2, the intensity at a depth of 4 cm is ___________ W/cm2.
a. 0.00000002
b. 0.0000002
c. 0.00002
d. 0.000002
a. 0.00000002( attenuation 8db intensity ratio 0.16)
PD is the ____ it takes for a pulse to occur.
a. period
b. duration
c. time
d. frequency
c. time
Ultrasound transducers convert ____ energy into ___ energy, and vice versa.
a. heat, light
b. electric, light
c. heat, electric
d. electric, ultrasound
d. electric, ultrasound
If a 6 MHz transducer images to a depth of 10 cm, to avoid range ambiguity, the maximum PRF permitted is ______.
a. 7.7 kHz
b. 6.0 kHz
c. 10.0 kHz
d. 1.54 MHz
a. 7.7 kHz
How many cycles are there in 1 second of continuous wave of 5 MHz ultrasound?
a. 5
b. 500
c. 5000
d. 5,000,000
e. none of the above
d. 5,000,000
The principle on which ultrasound transducers operate is the ____
a. Acouto-optic effect
b. Acoustoelectric effect
c. Piezoelectric effect
d. Doppler effect
e. Cause and effect
c. Piezoelectric effect
If the input power is 1 mW and the output is 10,000 mW, the gain is ____dB.
a. 10
b. 20
c. 30
d. 40
d. 40
Pulsed wave Doppler has what advantage over continuous wave Doppler?
a. Two side-by-side piezoelectric elements in one transducer permit duplex scanning
b. It has range resolution and eliminates range ambiguity
c. It eliminates aliasing when measuring high velocities
d. The pulse length is infinite in length
c. It eliminates aliasing when measuring high velocities
The wavelength of 7-MHz ultrasound in soft tissues is ____mm.
a. 0.54
b. 3.33
c. 1.54
d. 0.22
d. 0.22
The piezoelectric effect describes how ____ is converted into ____ by a ____.
a. electricity, an image, display
b. incident sound, reflected sound, boundary
c. ultrasound, electricity, transducer
d. ultrasound, heat, tissue
e. none of the above
c. ultrasound, electricity, transducer
If a display has a dynamic range of 20 dB and the smallest voltage it can handle is 200 mV, then the largest voltage it can handle is ______________________ V.
a. 20
b. 2.0
c. 0.2
d. 0.02
b. 2.0
Based on the following information put together, the DF is ____. The PD in soft tissue for a two-cycle pulse of frequency 5 MHz is ___. For a 1-kHz, the PRP is ____ms.
a. 0.0004
b. 0.004
c. 0.4
d. 0.04
0.0004
