Physics Ultrasound Bioeffects US
BIOEFFECTS US
Questions and Answers
- 1.
Which artifact results in improper side by side positioning of reflectors
- A.
Multipath
- B.
Comet tail
- C.
Refraction
- D.
Reverberation
Correct Answer
C. RefractionExplanation
Refraction is the correct answer because it refers to the bending of light as it passes through a different medium, causing a change in its direction. When light passes through a medium with varying refractive indices, such as air and water, it can result in the improper side by side positioning of reflectors. This is because the change in direction of light can cause the reflectors to appear shifted or misaligned, leading to improper side by side positioning.Rate this question:
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- 2.
Which process causes mirror image artifact
- A.
Reflection
- B.
Refraction
- C.
Propagation speed error
- D.
Attenuation
Correct Answer
A. ReflectionExplanation
Mirror imaging is created by an unexpected and uncorrected reflection of the ultrasound pulse off of a strong reflector.Rate this question:
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- 3.
What are the characteristics of medium that produces comet tail artifact?
- A.
Weak reflectors, closely spaced, low propagation speeds
- B.
Strong reflectors, widely spaced, high propagation speeds
- C.
Strong reflectors, closely spaced, low propagation speed
- D.
Strong reflectors, closely spaced, high propagation speed
Correct Answer
D. Strong reflectors, closely spaced, high propagation speedExplanation
Comet tail artifact is a type of artifact that occurs in ultrasound imaging. It appears as a long tail-like structure extending from a strong reflector. The characteristics of the medium that produce this artifact are strong reflectors, closely spaced, and high propagation speed. Strong reflectors produce a strong echo signal, and when they are closely spaced, the echoes from adjacent reflectors overlap and create the comet tail appearance. High propagation speed refers to the speed at which sound waves travel through the medium, and a higher speed causes the echoes to be closer together, contributing to the comet tail effect.Rate this question:
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- 4.
What is a comet tail artifact's fundamental mechanism of formation?
- A.
Reflection
- B.
Rarefaction
- C.
Refraction
- D.
Attenuation
Correct Answer
A. ReflectionExplanation
A comet tail artifact is formed due to the reflection of sound waves. When sound waves encounter a boundary between two different media, such as soft tissue and a gas-filled cavity, some of the sound waves are reflected back towards the transducer. This reflection creates a bright, comet-like tail on the ultrasound image. The reflected sound waves can provide valuable information about the structure and composition of the tissues being examined.Rate this question:
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- 5.
In diagnostic imaging, how does multipath artifact affect the image?
- A.
Poor angular resolution
- B.
Creation of hyperechoic regions
- C.
Mild image degradation
- D.
Gross horizontal misregistration
Correct Answer
C. Mild image degradationExplanation
Multipath artifact in diagnostic imaging refers to the distortion or interference caused by the reflections of sound waves bouncing off multiple surfaces before reaching the transducer. This can result in a slight degradation of the image quality, affecting its clarity and sharpness. While it may not cause significant problems like poor angular resolution or gross horizontal misregistration, it does lead to mild image degradation, making the image slightly less clear and accurate.Rate this question:
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- 6.
What causes side lobe artifact?
- A.
Sound beam bending
- B.
Linear array transducers architecture
- C.
Unexplectedly low acoustic attenuation
- D.
Acoustic energy radiating in a direction other than the beam's main axis
Correct Answer
D. Acoustic energy radiating in a direction other than the beam's main axisExplanation
Side lobe artifact occurs when acoustic energy radiates in a direction other than the beam's main axis. This can happen due to various factors such as improper focusing, diffraction, or interference. When the sound beam diverges or spreads out in unintended directions, it creates additional echoes that can appear as artifacts on the ultrasound image. These artifacts can degrade the image quality and make it difficult to accurately interpret the structures being imaged.Rate this question:
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- 7.
Grating lobes are most common with which type of transducer technology?
- A.
Annular array
- B.
Continuous wave
- C.
Mechanical scanner
- D.
Linear arrays
Correct Answer
D. Linear arraysExplanation
Grating lobes are most common with linear arrays because they occur when the ultrasound beam is transmitted at an angle that is greater than the main lobe. This happens because linear arrays consist of multiple transducer elements arranged in a line, and each element produces an individual beam. When the beams from the individual elements are not perfectly aligned, grating lobes can occur, causing unwanted side lobes in the ultrasound image.Rate this question:
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- 8.
True or False Grating lobes are a result of substantial acoustic energy directed outward from a linear array transducer, but not along the main axis of the sound beam.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Grating lobes occur when there is substantial acoustic energy directed outward from a linear array transducer, but not along the main axis of the sound beam. This means that there are additional lobes or beams of energy that are emitted from the transducer in directions other than the main beam. These grating lobes can cause artifacts and affect the quality of the ultrasound image. Therefore, the statement "Grating lobes are a result of substantial acoustic energy directed outward from a linear array transducer, but not along the main axis of the sound beam" is true.Rate this question:
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- 9.
Which technique of linear array transducers design has virtually elimated the appearance of grating lobe artifact on modern ultrasound systems?
- A.
Demodulation
- B.
Subdicing
- C.
Deconvolution
- D.
None of the above
Correct Answer
B. SubdicingExplanation
Subdicing is a technique used in linear array transducer design that has virtually eliminated the appearance of grating lobe artifact on modern ultrasound systems. Grating lobe artifact refers to the appearance of additional lobes or side lobes in the ultrasound image, which can degrade image quality and make it difficult to interpret. Subdicing involves dividing the transducer elements into smaller sub-elements, which helps to reduce the occurrence of grating lobe artifact by decreasing the spacing between the sub-elements. This technique improves the focusing capabilities of the transducer and enhances image resolution, resulting in clearer and more accurate ultrasound images.Rate this question:
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- 10.
Grating lobes are attributed only to array transducers.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Grating lobes are additional lobes that occur in the beam pattern of an ultrasound transducer array. These lobes are caused by the interference of sound waves from multiple elements in the array. Grating lobes can result in image artifacts and reduced image quality. Therefore, it is correct to say that grating lobes are attributed only to array transducers, as these lobes are a specific characteristic of transducer arrays and not typically found in single-element transducers.Rate this question:
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- 11.
How is shadowing artifact expressed?
- A.
Position structures too deep on the image
- B.
Locating structures in improper lateral position
- C.
Placing reflections in multiple locations
- D.
Reflectors being absent on the image
Correct Answer
D. Reflectors being absent on the imageExplanation
Shadowing artifact is expressed when reflectors are absent on the image. This means that the ultrasound waves are unable to penetrate through the structures and create a shadow behind them. Without the presence of reflectors, there will be a lack of information about the structures behind, resulting in a shadowing artifact on the image.Rate this question:
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- 12.
Which of these produces shadowing
- A.
Reverberation
- B.
Multipath
- C.
Reflection
- D.
Attenuation
Correct Answer
D. AttenuationExplanation
Attenuation refers to the reduction in the intensity or strength of a signal as it travels through a medium or encounters obstacles. In the context of shadowing, attenuation can occur when the signal is obstructed by objects or barriers, causing the signal strength to diminish and creating areas of shadow where the signal is weakened or lost. This can happen, for example, in wireless communication systems when signals are blocked by buildings or other physical structures, resulting in areas with poor or no signal coverage.Rate this question:
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- 13.
Acoustic focusing of an ultrasound beam may create which artifact
- A.
Side lobes
- B.
Refraction
- C.
Speckle
- D.
Enhancement
Correct Answer
D. EnhancementExplanation
Acoustic focusing of an ultrasound beam can enhance the quality and resolution of the image by concentrating the energy in a specific area. This can result in improved visualization of structures and increased sensitivity to detect abnormalities. Therefore, the artifact created by acoustic focusing is enhancement.Rate this question:
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- 14.
Which artifact is created by sound moving through a medium with a propagation speed less than soft tissue?
- A.
Vertical misregistration
- B.
Horizontal misregistration
- C.
Lateral resolution
- D.
Ring down
Correct Answer
A. Vertical misregistrationExplanation
Vertical misregistration is an artifact that occurs when sound waves move through a medium with a propagation speed less than soft tissue. This means that the sound waves take longer to travel through the medium, causing a misalignment or displacement of the echoes received. As a result, the vertical position of the echoes appears to be shifted or mismatched, leading to the creation of the vertical misregistration artifact.Rate this question:
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- 15.
While imaging a test object an ultrasound system displays one image 1.8 cm deeper than another. Upon measuring the test object, it is found that it is actually 2.0 cm deeper. What conslucsion can be drawn from this?
- A.
Soeed of sound in the test object is the same as soft tissue
- B.
Speed in the test object is less than that in soft tissue
- C.
Attenuation of sound in the test object is less than in soft tissue
- D.
Speed in soft tissue is less than that of the test object
Correct Answer
D. Speed in soft tissue is less than that of the test objectExplanation
The ultrasound system displays the image 1.8 cm deeper than another, but upon measuring the test object, it is found that it is actually 2.0 cm deeper. This suggests that the speed of sound in the test object is greater than the speed of sound in soft tissue. Since the sound waves are traveling faster in the test object, it takes less time for the sound waves to reach the same depth compared to soft tissue. Therefore, the conclusion that can be drawn is that the speed in soft tissue is less than that of the test object.Rate this question:
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- 16.
If an ultrasound pulse travels through a large mass in the body at a speed of 1.2 mm/us, what happens to the position of all echoes produced from reflectors shallower than the mass?
- A.
They are placed in too shallow a location on the image
- B.
They are placed in too deep a location on the image
- C.
They are likely to be placed at the correct depth
Correct Answer
C. They are likely to be placed at the correct depthExplanation
When an ultrasound pulse travels through a large mass in the body, it causes a decrease in the speed of the pulse. As a result, the time it takes for the pulse to reach the reflectors and return back to the transducer is longer. This longer time delay is accounted for by the ultrasound machine, and the echoes produced from reflectors shallower than the mass are placed at the correct depth on the image. Therefore, the correct answer is that they are likely to be placed at the correct depth.Rate this question:
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- 17.
If a sound pulse travels through a large mass at a speed of 1.2 mm/us, what happens to the position of echoes from reflectors deeper than the mass?
- A.
They are placed in too shallow a location on the image
- B.
They are placed in too deep a location on the image
- C.
They are likelyto be placed at the correct depth
Correct Answer
B. They are placed in too deep a location on the imageExplanation
When a sound pulse travels through a large mass at a speed of 1.2 mm/us, the speed of sound is slower than normal. This means that it takes longer for the sound pulse to reach deeper reflectors and return as an echo. As a result, the echoes from reflectors deeper than the mass will be delayed and appear to come from a deeper location on the image. Therefore, the correct answer is that they are placed in too deep a location on the image.Rate this question:
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- 18.
Which artifact is not affected by the shape or dimensions of an ultrasound pulse?
- A.
Lateral resolution
- B.
Slice thickness
- C.
Mirror imaging
- D.
Longitudinal resolution
Correct Answer
C. Mirror imagingExplanation
Mirror imaging is not affected by the shape or dimensions of an ultrasound pulse because it is a phenomenon that occurs when sound waves are reflected off a strong reflector, such as a bone or air interface, and create a mirror-like image on the opposite side. The shape or dimensions of the ultrasound pulse do not impact this reflection and creation of the mirror image.Rate this question:
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- 19.
True or False. Side lobe, grating lobe and refraction artifacts all reduce lateral resoltuion.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
These 3 artifacts all degrade lateral resoltuionRate this question:
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- 20.
True or False. Artifacts are likely to appear when the dimensions of the sound beam area are larger thant the dimensions of the reflections in the body.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Some artifacts, such as slice thickenss and axial resolution, result from the beam being larger than reflectors.Rate this question:
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- 21.
True or False. It is generally believed that the effects of ultrasound of biologic media are minimal.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Ultrasound bioeffects are substantial under certain conditions, including, but not limited to therapeutic ultrasound and lithotripsy.Rate this question:
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- 22.
Which of these terms best describe the empirical investation of bioeffects?
- A.
Cause - effect
- B.
Exposure - response
- C.
Cause - response
- D.
Exposure - cure
Correct Answer
B. Exposure - responseExplanation
The term "exposure - response" best describes the empirical investigation of bioeffects. This term refers to the study of the relationship between the exposure to a certain factor or agent and the resulting response or effect on biological systems. It implies that the level or duration of exposure to a specific factor can influence the response or outcome in living organisms. This term is commonly used in scientific research to understand the cause and effect relationship between exposures and their effects on biological systems.Rate this question:
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- 23.
TRUE OR FALSE. The mechanistic approach to the study of bioeffects and safety includes the identification of a theoretical construct that could produce an effect.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The mechanistic approach to the study of bioeffects and safety involves identifying a theoretical construct that could potentially cause an effect. This means that researchers analyze the underlying mechanisms and processes that could lead to biological effects or safety concerns. By understanding these mechanisms, scientists can better assess the potential risks and develop appropriate safety measures. Therefore, the statement "True" accurately reflects the inclusion of a theoretical construct in the mechanistic approach.Rate this question:
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- 24.
True or Fales. The emprical approach to the study of bioeffects and ultrasonic safety surveys data involves the finding a relationship between exposure and toxic effects.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The empirical approach to the study of bioeffects and ultrasonic safety surveys data involves finding a relationship between exposure and toxic effects. This means that researchers collect and analyze data to determine if there is a link between exposure to ultrasonic waves and any harmful effects on living organisms. By studying real-world data, scientists can gain a better understanding of the potential risks associated with ultrasonic technology. Therefore, the statement is true.Rate this question:
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- 25.
A bioeffect identified through the mechanistic approach rather than by the empirical approach is more likely to have clinical significance.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
The most clinically relevant bioeffect would be one identified both mechanistically and empircallyRate this question:
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- 26.
True or False. The AIUM considers an ultrasound-induced biologic tissue temperature rise of less than 2 degree centigrade above normal body temperature as safe for clinical studies.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
AIUM guidelines state that an exam is considered free of the potential for thermally induced bioeffects if the tissue temperature is within 1 degree C of normal.Rate this question:
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- 27.
According to the AIUM at what in stiu tissue temperature is there danger to a fetus?
- A.
100 degree C
- B.
98.6 degree F
- C.
1 degree F over normal tempeature
- D.
41 degree C
Correct Answer
D. 41 degree CExplanation
The AIUM states that there is danger to a fetus when the in situ tissue temperature reaches 41 degrees Celsius.Rate this question:
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- 28.
Which of the following ultrasound beams has a characteristic that is most likely to cause temperature elevation in soft tissue?
- A.
Strongly focused
- B.
Medium focused
- C.
Unfocused
Correct Answer
C. UnfocusedExplanation
Ultrasound beams that are unfocused have a characteristic that is most likely to cause temperature elevation in soft tissue. This is because unfocused beams distribute the energy over a larger area, resulting in less energy being concentrated in a specific spot. As a result, the energy is dispersed and absorbed by a larger volume of tissue, leading to a higher likelihood of temperature elevation. In contrast, strongly focused beams concentrate the energy into a smaller area, reducing the chances of temperature elevation. Medium focused beams fall in between the two extremes.Rate this question:
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- 29.
Which selection has the highest mechanical index?
- A.
High frequency, high power
- B.
High PRF, high intensity
- C.
Low frequency, high pressure
- D.
High spatial pulse length, high PRF
Correct Answer
C. Low frequency, high pressureExplanation
The mechanical index (MI) is a parameter used to describe the potential for bioeffects in ultrasound imaging. It is calculated using the peak rarefactional pressure and the frequency of the ultrasound waves. The higher the MI, the greater the potential for bioeffects. In this case, the selection "low frequency, high pressure" has the highest mechanical index because low frequency ultrasound waves and high pressure result in a higher MI compared to the other options.Rate this question:
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- 30.
What is epidemilogy the study of?
- A.
Large groups
- B.
The prevlaence of disease
- C.
Acoustic bioeffects on the fetus
- D.
In vitro effects
Correct Answer
B. The prevlaence of diseaseExplanation
Epidemiology is the study of the prevalence of disease within large groups. It focuses on understanding the patterns, causes, and effects of diseases in populations. By examining the distribution and determinants of diseases, epidemiologists can identify risk factors, develop preventive measures, and improve public health strategies.Rate this question:
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- 31.
What is the highest SPTA intensity of an unfocused ultrasound wave where there have been no observed bioeffects
- A.
1 mW/cm^2
- B.
10 mW/cm^2
- C.
100 mW/cm^2
- D.
1 W/cm^2
Correct Answer
C. 100 mW/cm^2Explanation
The highest SPTA intensity of an unfocused ultrasound wave where there have been no observed bioeffects is 100 mW/cm^2. This means that at intensities below 100 mW/cm^2, there have been no reported negative effects on living tissue.Rate this question:
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- 32.
True or False. On reason focused ultrasound beams with low intensities are less likely to cause bioeffects is that a foused beam is less efficient in heating a large mass of tissue to a critical temperature.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
A focused ultrasound beam with low intensity is less likely to cause bioeffects because it is less efficient in heating a large mass of tissue to a critical temperature. This means that the energy from the ultrasound beam is not concentrated enough to cause significant heating in a large area of tissue, reducing the risk of harmful effects.Rate this question:
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- 33.
The AIUM suggest that in vitro research confirming bioeffects is valuable and valid. Their results are significant and should be directly applied to the clinical arena.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
The statement suggests that the AIUM believes in vitro research confirming bioeffects is valuable and valid, and that its results should be directly applied to the clinical arena. However, the correct answer is false, indicating that this statement is not accurate. The AIUM may value in vitro research, but it does not necessarily suggest that its results should be directly applied to the clinical arena.Rate this question:
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- 34.
Certain studies of bioeffects are performed in vitro. What is the meaning of in vitro?
- A.
Visible in a living organism
- B.
Observations based on experiments
- C.
Discernible in a test tube
- D.
Perceptible in a living human being
Correct Answer
C. Discernible in a test tubeExplanation
An in vitro experiment is performed out of the body and in an artifical environment. The observations may be described as "in a test tube."Rate this question:
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- 35.
Which artifact results in improper side by dise positioning of reflectors?
- A.
Multipath
- B.
Comet tail
- C.
Refraction
- D.
Reverberation
Correct Answer
C. RefractionExplanation
Refraction artifact results from an acoustic pulse bending and changing direction. This change of direction is not corrected by the ultrasound system and results in an improper lateral location of reflectors on the image.Rate this question:
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- 36.
The effects of soft tissue on US are called
- A.
Acoustic proliferation properties
- B.
Dynamic effects
- C.
Acoustic propagation properties
- D.
Biologic effects
Correct Answer
C. Acoustic propagation propertiesExplanation
The term "acoustic propagation properties" refers to the effects of soft tissue on ultrasound. When ultrasound waves pass through soft tissue, they are affected by various factors such as absorption, scattering, and reflection. These properties determine how the ultrasound waves propagate through the tissue and are crucial in generating high-quality ultrasound images. Therefore, acoustic propagation properties accurately describe the effects of soft tissue on ultrasound.Rate this question:
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- 37.
Which of the following sound waves is ultrasonic and least useful in diagnostic imaging?
- A.
30kHz
- B.
8MHz
- C.
8000 Hz
- D.
3000 kHz
- E.
15Hz
Correct Answer
A. 30kHzExplanation
The sound waves with a frequency of 30kHz are considered ultrasonic. Ultrasonic waves have frequencies above the range of human hearing, typically above 20kHz. Diagnostic imaging techniques such as ultrasound use sound waves in the range of 2-18MHz, which allows for detailed imaging of internal organs and tissues. Therefore, the sound waves with a frequency of 30kHz are least useful in diagnostic imaging as they are below the typical range used for this purpose.Rate this question:
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- 38.
What is the name of the receiver function that corrects for attenuation?
- A.
Compression
- B.
Compensation
- C.
Rejection
- D.
Demodulation
Correct Answer
B. CompensationExplanation
The correct answer is "compensation" because the term "compensation" refers to the process of correcting for attenuation, which is the reduction in signal strength as it travels through a medium. Attenuation can occur in various forms, such as in audio signals or in seismic waves. To counteract this reduction in signal strength, a compensation function is applied to restore the original signal strength, allowing for a more accurate and reliable transmission or measurement.Rate this question:
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- 39.
The process of reducing the difference between the smallest and largest voltages is called?
- A.
Demodulation
- B.
Compression
- C.
Compensation
Correct Answer
B. CompressionExplanation
Compression is the correct answer because it refers to the process of reducing the difference between the smallest and largest voltages. In this context, compression can be understood as a technique used in signal processing to decrease the dynamic range of a signal, making it more manageable and easier to transmit or store. By compressing the voltage range, the signal can be effectively represented with fewer bits or transmitted with less distortion, improving efficiency and quality.Rate this question:
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- 40.
If the lines per frame is increased while the imaging depth is unchanged then:
- A.
Frame rate increases
- B.
Number of shades of gray decreases
- C.
The frame rate decreases
- D.
This cannot happen
Correct Answer
C. The frame rate decreasesExplanation
If the lines per frame are increased while the imaging depth remains unchanged, it means that more lines are being captured within each frame. This requires more time to capture all the lines, resulting in a slower frame rate. Therefore, the frame rate decreases.Rate this question:
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- 41.
At the focus, the beam diameter is __________the transducer diameter
- A.
Equal to
- B.
Half
- C.
Double
- D.
One - fourth
Correct Answer
B. HalfExplanation
At the focus, the beam diameter is half the transducer diameter. This means that the diameter of the beam of ultrasound waves narrows down to half the size of the transducer diameter at the focal point. This is because the ultrasound waves converge and become more focused at the focal point, resulting in a smaller beam diameter compared to the transducer diameter.Rate this question:
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- 42.
TRUE OR FALSE The digital scan converter has a number of pixels assigned to each bit.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
The digital scan converter does not have a number of pixels assigned to each bit. In a digital scan converter, each pixel is represented by a certain number of bits, not the other way around. The number of bits determines the level of detail and color depth that can be represented for each pixel. Therefore, the statement is false.Rate this question:
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- 43.
The more bits per pixel
- A.
The better the resolution
- B.
The higher the pixel density
- C.
The more shades of gray
- D.
The hiher the reliability
Correct Answer
C. The more shades of grayExplanation
The statement suggests that as the number of bits per pixel increases, there are more shades of gray available. This implies that the image or display has a higher level of detail and more variations in color, leading to a better resolution. The increase in shades of gray also indicates a higher pixel density, which means that there are more pixels packed into a given area, resulting in a clearer and more detailed image. The reliability of the image or display is not directly related to the number of bits per pixel, so it is not a valid explanation for the given answer.Rate this question:
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- 44.
If the transducer diameter increases, the lateral resolution at it smallest dimension is:
- A.
Increased
- B.
Decreased
- C.
Unchanged
Correct Answer
A. IncreasedExplanation
When the transducer diameter increases, the lateral resolution at its smallest dimension is increased. This is because a larger transducer diameter allows for a wider beam width, resulting in a larger area of coverage. As a result, the ability to distinguish between two closely spaced objects improves, leading to an increase in lateral resolution.Rate this question:
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- 45.
What is the actual time that an US machines is creating a pulse
- A.
Duty factor
- B.
Period
- C.
Pulse period
- D.
Pulse duration
Correct Answer
D. Pulse durationExplanation
The pulse duration refers to the actual time that a US machine is creating a pulse. It represents the length of time that the ultrasound wave is being transmitted. The duty factor, period, and pulse period are all related to the timing and characteristics of the pulse, but they do not specifically represent the actual time of pulse creation. Therefore, pulse duration is the correct answer in this context.Rate this question:
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- 46.
An US wave travels through two media and has attenuation of 3dB in the first and 5 dB in the secon. What is the total attenuation?
- A.
15dB
- B.
8dB
- C.
3/5dB
- D.
5/8dB
Correct Answer
B. 8dBExplanation
The total attenuation can be calculated by adding the attenuations of the two media. In this case, the first medium has an attenuation of 3dB and the second medium has an attenuation of 5dB. Therefore, the total attenuation is 3dB + 5dB = 8dB.Rate this question:
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- 47.
Volume has which of the following units?
- A.
Cm
- B.
Cm^2
- C.
Cm^3
- D.
Cm^4
Correct Answer
C. Cm^3Explanation
The correct answer is cm^3 because volume is a measure of the amount of space occupied by an object in three dimensions. It is calculated by multiplying the length, width, and height of an object. Since each dimension is measured in centimeters, the resulting unit for volume is cubic centimeters (cm^3). This represents the amount of cubic space that an object occupies.Rate this question:
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- 48.
TRUE OR FALSE Axial resolution is affected by focusing
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Axial resolution refers to the ability of an imaging system to distinguish between two closely spaced objects along the direction of the imaging beam. Focusing, on the other hand, relates to the adjustment of the beam to converge at a specific depth within the sample. These two concepts are not directly related, and therefore, focusing does not affect the axial resolution. Hence, the correct answer is False.Rate this question:
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- 49.
TRUE OR FALSE Increasing the frequency increases the penetration depth
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Increasing the frequency does not increase the penetration depth. In fact, higher frequencies result in decreased penetration depth. This is because as the frequency increases, the energy of the wave is concentrated more towards the surface, resulting in less energy reaching deeper layers. Therefore, increasing the frequency actually reduces the ability of the wave to penetrate deeper into a material.Rate this question:
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- 50.
What is the fraction of time that sound is transmitting
- A.
Duty fraction
- B.
Pulse duration
- C.
Period
- D.
PRF spatial duration
Correct Answer
A. Duty fractionExplanation
The duty fraction refers to the fraction of time that sound is transmitting. It represents the ratio of the pulse duration (the time during which sound is being transmitted) to the period (the total time of one complete cycle). Therefore, the duty fraction is a measure of how much of the total period is occupied by the transmission of sound.Rate this question:
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