Ch. 1 Foundations of Sonography (2) Flashcards
Acoustics is the study of _______, _______, and _________sound waves.
Generating, propagating, and receiving
Ultrasound is defined as sound frequencies beyond the upper limits of human hearing, that is, greater than _________.
20 Kilohertz
Name the three pioneers who made a significant contribution to ultrasound
John Wild, Dr. Hellmuth Hertz, Inge Elder
The terms ________, __________, and __________ have all been used to describe an imaging technique by which soft tissue structures of the body are visualized by recording the returning reflection of ultrasonic waves directed into the body.
Diagnostic Medical ultrasound, ultrasound, and ultrasonography
The term that applies to the ultrasound evaluation of cardiac structures is ________.
Echocardiography
One who performs ultrasound studies and gathers data under the direct or indirect dupervision of a physician is a __________
Sonographer
The qualities of a good sonographer are , , ,
- Intellectual curiosity
- Perseverance
- Ability to conceptualize two dimensional images into a three dimensional format
- Quick and analytical mind
- Technical amplitude
- Good physical health
- Independence and initiative
- Emotional stability
- Communication skills
- Dedication
As the ceramic element vibrates, it periodically presses against and pulls away from the adjacent medium with resultant particle __________ and ____________in the meduim
Compression and rarefraction
A transducer converts_________ energy into ___________ energy.
Electrical into mechanical
A propagation of energy that moves back and forth or vibrates at a steady rate is a __________
Wave
The time required to produce each cycle depends of the _________of the transducer
Frequency
The distance between two peaks over a period of time is the _________
Wavelength
Wavelength is inversely related to frequency, which means that the higher the frequency, the _________ the wavelength
Shorter
As frequencies become higher, the pulse duration ________, yielding a decrease in the depth of field
Decreases
The rate at which energy is transmitted is referred to as the _________
Power
Power per unit area is defined as __________
Intensity
If you double the power, the intensity ______
Doubles
The piezoelectric effect was first described by the ________ brothers in 1880
Curie
Air-filled structures , such as lungs and stomach, or gas-filled structures, such as bowel _______ sound transmission
Impede
Bone conducts sound at a ________speed than soft tissue
Faster
Normal transmission of sound through soft tissue travels at _________m/sec
1540
Acoustic impedance is the product of the ___________ in a medium and the density of that medium
Velocity of Sound
The angle of reflection is equal to the _______
Angle of incidence
If specular reflectors are aligned __________ to the direction of the transmitted pulse, they reflect sound directly back to the active crystal elements in the transducer and produce a strong signal
Perpendicular
The sum of acoustic energy losses resulting from absorption, scattering, and reflection is the ___________
Attenuation
Minimum reflector separation along the sound path required to produce separate echoes is _______ resolution
Axial
The __________ resolution is the ability to produce separate echoes perpendicular to the sound path; it is affected by the transducer diameter and focusing
Lateral
Lateral resolution is determined by _________
Beam width
________ resolution refers to the ability to resolve ofbjects that are the same distance from the transducer but are located perpendicular to the plane of imaging
Azimuthal
Three criteria that determine the type of transducer selected for a particular examination are . . .
- Examination
- Size of patient
- Amount of fatty or muscular tissue present
The number of pulses launched per second is the __________
Pulse repetition frequency (PRF)
If the gain is set too ________, artificial echo noise will be displayed throughout the image
High
A one-dimensional image displaying the amplitude strength of the returning echo signals along the vertical axis and the time (distance) along the horizontal axis is produced by __________
Amplitude modulation
The intensity (amplitude) of an echo attained by varying the brightness of a dot to correspond to echo strength is displayed by the ______________method
Brightness modulation
The condition of assigning each level of amplitude a particular shade of gray is referred to as the __________
Gray Scale
The __________ displays time along the horizontal axis and depth along the vertical axis to depict movement, especially in cardiac structures
Motion mode
A dynamic presentation of multiple image frames per second over selected areas of the body is provided by ________imaging
Real time
With pulse Doppler, for accurate detection of Doppler frequencies, the Doppler signal must be sampled at least ______for each cycle in the wave
Twice
When the Nyquist limit is exceeded, an artifact called __________occurs
Aliasing
