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ultrasound physics
| Term | Definition |
|---|---|
| propagation speed increases as frequency increases. True or False. | False |
| what interaction causes a change of direction in the sound beam as it moves from one medium into another | Refraction |
| what term describes the rate of flow of energy over a small area. | Intensity |
| what describes transverse wave: A) a particle of motion is a long the direction of propagation. B) Particle mothion is perpendicular to the direction of propagation, C) long wavelength over 1cm., D) dong wavelength over 1mm | B) particle motion is perpendicular to the direction of propagation |
| which is most likely to produce scatter: a. red blood cells b. skull c. diaphragm d. distilled water | A. red blood cells |
| if refraction occurs, there has to be an oblique incidence and propagation speed difference. T or F | True |
| ____is a major cellular component of blood. | erythrocyte |
| at what area of he body is hydrostatic pressure zero? | at the level of the right atrium |
| as hematocrit increases, viscosity_____ | increases |
| As you decrease vessel lumen size, ------resistance | increase in |
| _____ principle demonstrates the inverse relationship between pressure (potential energy) and velocity (kinetic energy) | Bernouilli's Principle |
| what is cardiac output | the volume of blood that is pumped out of the heart per minute |
| ____artifact is creted by small but highly reflective objects and appears multiple small bands. (seen with surgical clips/prostatic valves-metal) | comet tail |
| At what interval should quality assurance evaluations be performed? | routinely |
| zWhat is the response of the medical community to reports claiming that obstetrical scanning may be harmful. | Perform exams on all patients when the benefits outweigh the risks. |
| A surgical clip will most likely demonstrate ____artifacts | comet tail |
| If the received and transmitted frequencies are identical, ____ will not occur. | Doppler shift |
| True or False: It is common to visualize artifacts when the dimension of the sound beam is larger than the reflector's dimension. | True |
| Shadowing and enchancement are a result of which type of imaging artifact? | Attenuation |
| Normally, what happens to venous flow in the legs during inspiration? | Decreases |
| which of the following scan converters will provide the best spatial resolution: A) 256x256 B) 512x512 C) 128x128 D) 1000x1000 | D. 1000x1000 |
| an 8-bit binary number referred to as a: | Bite |
| sound with a frequency of 4 MHz is created by a transducer. What is the harmonic frequency? | 8 MH |
| In binary numbers, how many values are used for each digit? | 2 |
| Enchancement of echo reflections occur distal to a: | weakly attenuating structure |
| which of the following is a disadvantage of duplex: A) decrease in frame rate B) combines imaging and Doppler information C) allows measurement only of mean velocities D) inability to use high operating frequencies | A) decrease in frame rate |
| Nosie within the Doppler signal is known as ____ | clutter |
| Spectral thickening is also known as _______ | spectral broading |
| Power Doppler imaging displays the signal's _____ | energy |
| What standard is best used in a quality assurance program? | objective |
| ______resolves aliasing. | Decreasing the depth of the sample volume |
| smaller arteries commonly demonstrate_____flow | laminar |
| what artifact in color Doppler imaging exhibits contiguous, contrasting colors within a vessel, indicative of maximum flow in the opposite directions. | color aliasing |
| The Nyquist limit is equal to _____ the pulse repetition frequency. | one half |
| A major advantage of continuous wave Doppler is the _____ | ability to measure high velocities. |
| The Doppler equation determines the change in ____ and ____frequencies. | transmitted, received |
| observed frequency changes in moving structures most accurately defines: | Doppler effect |
| which artifacts improperly displays a true reflectors location? | range ambiguity |
| _____ ____is the technique used to perform spectral analysis on color Doppler data. | auto correlation |
| what decreases the likelihood of range ambiguity artifacts? | decreasing the PRF |
| weakening of echoes distal to a strongly attenuating structure is_____ | shadowing |
| One advantage of large packet size is______ | Increased Doppler Accuracy |
| _______ law predicts beam direction through an interface. | Snell's |
| A longitudinal wave is denoted by particle motion_____the direction of propagation. | a long |
| True or False: In a given medium, attenuation is unrelated to the speed of sound. | True |
| The higher the transducer frequency, the ______the wave length. | shorter |
| what is the wavelength in soft tissue for a 10 MHz ultrasonic wave? | 0.15 mm |
| What is the frequency range for human hearing? | 20-20,000 MHz |
| which material has the lowest acoustic velocity? A. bone B. fat C. muscle D. Air | Air |
| what term describes the distance from one cycle for a wave? | wave length |
| ______flow is a normal variation of venous blood flow, with respiratory variations. | phasic |
| ______ artifact produces an image with an incorrect number of reflectors. | side lobes |
| how are frequency and period related. | indirectly |
| how are amplitude and power related | directly |
| harmonics are created by _______behavior. | Nonlinear |
| read zoom displays only _____data. | original |
| _____flow, is arterial flow that exhibits a constant velocity across the vessel. | plug |
| code excitation allows for multiple_____zones, and ______frequencies. | focus, harmonic |
| ______ is a volume picture element | voxel |
| ______is the number of frames per second necessary for a real time image to be free of flicker. | 30 |
| true or false the gray scale display was made possible when digital scan converters replaced analog scan converters. | False |
| which of the following is most likely related to pixel density? a. log compression b. spatial resolution c. contrast resolution d. temporal resolution | spatial resolution |
| coded excitated takes place in the_____ | pulser |
| are wave length and intensity related? | they are not related |
| ______ _______ measures the resistance of sound passing through a medium. | acoustic impedence |
| analog scanners: a. function perfectly as peak deflectors b. have greater image sharpness c. store any increment of signal amplitude d. have better image quality | c. store any increment of signal amplitude |
| ______ _______ describes the reflection of ultrasound at large smooth interfaces. | specular reflections. |
| _____ is the unit for measuring acoustic impedence. | Rayls |
| how are power and intensity related? | directly |
| adaptive TGC averages local and global ____ to give ___ to all images. | gain, uniformity |
| Image update, write res, and panning are all forms of ____ processing. | pre |
| are small or large vessels more resistive to flow? | small |
| as flow increases in a large vessel, its profile is said to be ____ or ____ laminar flow. | plug or blunt |
| when a lumen is less than 1 mm in diameter, blood will act as a ____ rather than a liquid. | cell |
| _____ is the lower frequency limit for ultrasound. | 20,000 Hz |
| enhancement, shadowing, and focal banding are all types of _____ artifact. | attenuation |
| this artifact occurs when multiple structures are along the main axis of the beam but appear as one reflector on the image. | axial resolution |
| frequency and wave length are _______ related. | indirectly |
| stiffness and sound speed are _______ related. | directly |
| acoustic velocity and density are ______ related. | indirectly |
| ______ is the rate of flow of energy over a small are. | intensity |
| _______ wave, particle motion is perpendicular to the direction of propagation. | transverse wave. |
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