A
The term used to describe the effects of an ultrasound wave on living tissues.
Biologic effects
With this type of wave, the direction of particle motion is perpendicular to the direction the wave is traveling
transverse
The combination of waves when they exist at the same location and time.
interference
2-20 MHz
range of frequencies in diagnostic ultrasound
This is the reciprocal of frequency
period
The intensity of a signal declines from 1.5mW/cm^2 to 0.75mW/cm^2. How many decibels is this change in intensity?
-3 dB
What are the units of pulse duration (PD)?
units of time (sec, years, etc)
Electric ____ applied to a transducer are converted to ultrasound.
voltages
PACS stands for _______.
Picture Archiving and Communications System
What doppler angle is the most inaccurate?
less than 30 or more than 60 degrees
How long does it take for sound to make a round trip to and from the skin’s surface to a reflector depth of 1 cm in soft tissue?
13 us
This will happen to the amplitude of wave as it travels through the body
decreases
These factors determine the wavelength
sound source and medium
The fraction of time that pulsed ultrasound is on is called ______.
Duty Factor (DF)
These determine the intensity of a sound beam after it has traveled through the body
sound source and medium
If traveling through the same medium, which would have a longer wavelength, a 20 kHz pulse or a 15 MHz pulse?
20 kHz
How many decibels represents a 100 fold increase in the intensity of an acoustic pulse?
20
The pulse repetition frequency is the...
... reciprocal of pulse repetition period
Panoramic imaging expands the image ___
Beyond the normal limits of a transducer's field or view.
Which of the following frequencies is operated by the thinnest element?
10.0 MHz
What can pulsed doppler differentiate that continuous wave cannot?
location
The shorter pulse duration, the better the image. True or False?
True
If traveling through the same medium, which would have the lowest propagation speed, 2 MHz pulse or 10 MHz pulse?
neither, they're the same
Which of the following operator controls adjusts compression?
Dynamic Range
The useful frequency range for the most diagnostic applications is _______ MHz.
2-20
This term describes a doubling it's original value for the amplitude of an acoustic wave
3 dB
Which of the following pulsed-wave techniques demonstrates the lowest sonographic output?
gray-scale
A sound beam travels 9 cm in soft tissue. The attenuation coefficient is 3 dB/cm. What is the total attenuation the sound beam experienced?
27 dB
What intensity is closely related to tissue heating?
SPTA
What is attached to the rear face of the transducer element?
Damping
Ultrasound transducers operate according to ________.
The Piezoelectric Principle
What is the meaning of a thermal index =3
tissue temperature may rise 3C
Axial resolution describes the accuracy related to visualizing two structures that are ____ to a sound beams main axis.
Parallel
Which of the following has the same meaning as transducer diameter?
Aperture
Optison and Imagent are names of ultrasound ______.
Contrast Agents
Partial-volume artifact is also called _______.
Section thickness artifact
The fraction of time that pulsed ultrasound is on is called
Duty Factor (DF)
Which of the frequencies is operated by the thinnest element.
10.0 MHz
Which two properties help establish the acoustic impedance of a medium?
Density and stiffness
A relationship between two numbers
What is a decibel?
Which operator control adjusts compression?
Dynamic range
Which artifact displaces structures axially?
Speed Error
A doppler exam is performed with a 5 MHz probe and a PRF of 15 kHz. What doppler shift will create aliasing?
Any frequency OVER 7.5 kHz (1/2 the PRF)
In soft tissue, sound travels to a reflector and back to the transducer in 39us. How deep is the reflector?
3 cm
Retention of previous frames while new echo information is added in the same scanning plane is called ________.
Interpolation
The width of the sample volume is determined by the _____.
Beam width and sample volume depth
Almost al ultrasound contrast agents contain _________.
Gas Microbubbles
If the echo returns 104 us after a pulse wave was emitted by a transducer, at what depth is the structure that produced the echo located?
8.0 cm
The useful range for most diagnostic applications is?
2-20 MHz
What is the maximum permissible value for both the intensity reflection coefficient and the intensity transmission coefficient?
1
What happens to the PRF when a sonographer increases the maximum imaging depth?
decreases
What can the sonographer do to improve clutter?
reposition the transducer
Which of the following is achieved within the Fresnel zone?
Focusing on the sound beam
An ultrasound system is set at 0 dB and is transmitting at full intensity. What is the output power when the system is transmitting at 50% full intensity?
-3 dB
An ultrasound pulse has a PRP of 1.2 msec, a spatial pulse length of 2 mm, and a wavelength of 0.4 mm. what is the axial resolution of the system?
1.0 cm