SPI Exam Review
ultrasound imaging type in which pulses are reflected and used to produce a display ️️pulsed wave
brightness of the dots on image ️️amplitude
round-trip travel time per cm in soft tissue ️️13 microseconds
A line produced on a display that represents ultrasonic ec...
ultrasound imaging type in which pulses are reflected and used to produce a display ✔️✔️pulsed wave
brightness of the dots on image ✔️✔️amplitude
round-trip travel time per cm in soft tissue ✔️✔️13 microseconds
A line produced on a display that represents ultrasonic echoes returning from the body. A sonographic
image is composed of many such lines. ✔️✔️scan line
Type of image presented in a rectangular format.
- Each pulse travels in same direction
- Different starting point for each pulse
- Yields series of parallel scan lines ✔️✔️linear
Type of image presented in a pie-slice or wedge shaped format.
- Each pulse originates from the same starting point
- Subsequent pulses go out in different directions from previous ones ✔️✔️sector
Frequency change tracking caused by motion of reflectors towards or away from the transducer
- Used extensively in vascular & cardiac ultrasound ✔️✔️Doppler Shift
The presentation of two-dimensional, real-time Doppler-shift information superimposed on a real-time,
gray-scale, anatomic, cross-sectional image. Flow directions toward and away from the transducer (i.e.,
positive & negative Doppler shifts) are presented as different colors on the display. ✔️✔️Color
Doppler
Unit of power or intensity ratio; also a unit of amplitude ratio ✔️✔️decibel
,doubled intensity in dB ✔️✔️3 dB
mathematical numerical system in which the number of 10s that are multiplied together in order to
equal the number
Log₁₀ of 100 = 10 × 10 = 100 or 10²
Log₁₀ of 100 = 2 ✔️✔️logarithm
What transports energy, not matter? ✔️✔️wave
Type of sound wave that requires a medium to travel in and, therefore, cannot propagate in a vacuum.
✔️✔️mechanical
Regions of high density and pressure in a compressional wave. ✔️✔️compression
Region of low density and pressure in a compressional wave. ✔️✔️rarefaction
What are the 3 acoustic variables? List them alphabetically. ✔️✔️density, distance, pressure
,unit of frequency, one cycle per second ✔️✔️hertz
20 → 20,000 Hz (20 kHz) ✔️✔️audible sound
2 to 15 MHz ✔️✔️What is the useful diagnostic frequency range for ultrasound in humans?
time per cycle
- Equation: If T = period in microseconds (µs) and ƒ = frequency in megahertz (MHz), then
T (µs) = 1/ƒ (Mhz)
- Reciprocal of frequency equation ✔️✔️period
As frequency increases, period _________. ✔️✔️decreases
length of space over which a cycle occurs
- Abbreviated: λ (lambda) ✔️✔️wavelength
0.1 → 0.8 mm ✔️✔️What is the typical ultrasound wavelength range?
speed with which a wave moves through a medium
Units: mm/μs, m/s
Abbreviation: c ✔️✔️propagation speed
What two properties of a medium affect its propagation speed? ✔️✔️density, stiffness
1.54 mm/μs OR 1540 m/s ✔️✔️speed of sound in soft tissue
Order the following by propagation speed from slowest to fastest:
bone, fat, air, muscle, liver ✔️✔️air, fat, liver, muscle, bone
, the resistance that sound encounters in traveling through a medium ✔️✔️impedance
unit of impedance ✔️✔️Rayl
equation that illustrates relationship between round-trip pulse travel time, propagation speed, and
distance to the reflector ✔️✔️range equation
(PW) the number of pulses that occur in 1 sec; sometimes called pulse repetition rate ✔️✔️pulse
repetition frequency
When distance (depth) increases, PRF ---------. ✔️✔️decreases
What must the sonographer change to alter the PRF? ✔️✔️depth
Interval of time from the beginning of one pulse to the beginning of the next.
** Includes pulse time & listening time **
Units: Seconds (s) ✔️✔️pulse repetition period
PRP increases because the system must listen longer for pulse to return from longer distance.
✔️✔️What happens to PRP when distance (depth) increases:
Interval of time from beginning to end of a pulse
Units: µs (microseconds) ✔️✔️pulse duration
0.5 → 3.0 µs
** NOT controlled by sonographer ✔️✔️What is the typical range for pulse duration in ultrasound?
Percent time that ultrasound is transmitting ✔️✔️duty factor
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