Rt Simulation Examination 2

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1. What determines the frequency of a sound beam from a pulsed transducer?

Explanation

The frequency of a sound beam from a pulsed transducer is determined by the thickness of the PZT material. The PZT thickness affects the resonant frequency of the transducer, which in turn determines the frequency of the sound beam produced.

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About This Quiz
Rt Simulation Examination 2 - Quiz

This is a Simulated Examination for Gulf RT Examinations taken from Last Month's HAAD Feedbacks.
This examination contains 100 of the most UPDATED EXAMS from Abu Dhabi,... see moreKSA, and UAE.
Take this examination for 120 minutes. You need to get 86% to pass the HAAD. 60% to pass MOH, DHA, or Prometrics.
Please text 0919-286-29-29 in the Philippines or visit our website www. Rtonline. Weebly. Com THIS IS YOUR ASSESSMENT FOR ANY GULF RT EXAMINATIONS INCLUDING HAAD RT, SAUDI PROMETRICS, DUBAI DHA, AND UAE MOH. THE QUESTIONS HERE ARE TAKEN FROM THIS ACTUAL EXAMINATIONS, SO PASSING THIS ASSESSMENT EXAM WILL GIVE YOU A HIGH PROBABILITY OF PASSING THE SAID EXAMINATIONS see less

2. Shadowing may result from high amounts of reflection of US energy.

Explanation

Shadowing can occur when there is a high amount of reflection of ultrasonic (US) energy. When US energy reflects off surfaces, it can create areas where the energy is blocked or absorbed, resulting in shadowing. This phenomenon is commonly observed in medical imaging, where certain structures or tissues may not be clearly visible due to shadowing caused by reflection of the US waves. Therefore, the given statement is true.

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3. 10000 gauss = _ Tesla

Explanation

The answer is 10000T because gauss and tesla are both units used to measure magnetic field strength. 1 tesla is equal to 10000 gauss, so 10000 gauss is equivalent to 10000T.

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4. Which has the greatest amount of attenuation?

Explanation

Bone has the greatest amount of attenuation because it is denser and contains more minerals compared to the other options. Attenuation refers to the reduction in the intensity of a signal as it passes through a medium. In this case, bone is more effective at absorbing and scattering the signal, resulting in a higher level of attenuation compared to fat, water, and muscle.

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5. True of False:  With standard diagnostic imaging instrumentation, the sonographer has the ability to vary the amplitude of a sound wave produced by the transducer.

Explanation

With standard diagnostic imaging instrumentation, the sonographer does have the ability to vary the amplitude of a sound wave produced by the transducer. This is typically done by adjusting the power output of the ultrasound machine, which controls the strength of the sound waves being emitted. By increasing or decreasing the amplitude, the sonographer can adjust the intensity of the sound waves and optimize the image quality for different types of examinations or patient conditions.

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6. What happens to venous blood flow to the heart during expiration?

Explanation

During expiration, the diaphragm and intercostal muscles relax, causing a decrease in thoracic volume. This decrease in thoracic volume leads to an increase in intrathoracic pressure. As a result, the pressure inside the thoracic cavity becomes higher than the pressure in the vena cava, causing a decrease in venous blood flow to the heart. Therefore, the correct answer is "decreases".

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7. For Doppler, which incident angle reults in no shift?

Explanation

When it comes to Doppler effect, an incident angle of 90 degrees results in no shift. The Doppler effect is the change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. When the incident angle is 90 degrees, it means that the observer is directly facing the wave source, resulting in no change in frequency or wavelength. This is because there is no component of the wave's motion along the line of sight of the observer, causing no shift to occur.

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8. Decimal uses a base of 10, binary uses a base of

Explanation

Binary uses a base of 2. In binary, there are only two digits, 0 and 1, which represent the absence or presence of a value. Each digit in a binary number represents a power of 2, starting from the rightmost digit. Therefore, the base of binary is 2.

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9. What determines the intensity of an ultrasound beam after it has traveled through the body?

Explanation

The intensity of an ultrasound beam after it has traveled through the body is determined by both the sound wave's source and the medium through which the sound travels. The source of the sound wave determines the initial intensity of the beam, while the medium through which it travels can affect the attenuation or absorption of the sound wave, leading to changes in intensity. Therefore, both factors play a role in determining the intensity of the ultrasound beam after it has passed through the body.

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10. Which of the following terms best describes the relationship between frequency and wavelength for sound traveling in soft tissue?

Explanation

The term "inverse" best describes the relationship between frequency and wavelength for sound traveling in soft tissue. Inverse means that as one variable increases, the other variable decreases, and vice versa. In this case, as the frequency of the sound waves increases, the wavelength decreases, and as the frequency decreases, the wavelength increases. This relationship is consistent with the behavior of sound waves in soft tissue.

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11. If the frequency is decreased, the numerical value of the radial resolution is

Explanation

When the frequency is decreased, the numerical value of the radial resolution is increased. Radial resolution refers to the ability to distinguish between two points in an image along the radial direction. A higher numerical value indicates a greater ability to distinguish between these points, which means that the radial resolution is increased. This is because decreasing the frequency results in a longer wavelength, which increases the distance between the points that can be resolved. Therefore, the radial resolution is directly affected by the frequency, and decreasing it leads to an increase in the numerical value of the radial resolution.

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12. Which of the following has a propagation speed closest to "soft tissue"?

Explanation

Muscle has a propagation speed closest to "soft tissue" because both muscle and soft tissue have similar physical properties and compositions. Soft tissue refers to the connective tissues in the body, including muscle tissue, which is made up of cells and fibers. The propagation speed of sound waves in muscle tissue is similar to that in other soft tissues, such as tendons and ligaments. In comparison, fat, bone, and air have different compositions and densities, resulting in different propagation speeds for sound waves.

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13. What is displayed on the y axis of an m-mode image?

Explanation

In an m-mode image, the y-axis represents the time of flight. This refers to the time it takes for an ultrasound beam to travel to a structure and back to the transducer. By measuring the time of flight, the m-mode image can display the depth or position of different structures within the body. This information is crucial in diagnosing and monitoring various conditions, as it allows healthcare professionals to visualize the movement and function of organs and tissues over time.

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14. Refraction only occurs if there is :

Explanation

Refraction occurs when light passes from one medium to another at an angle, causing it to change direction. In this case, the correct answer states that refraction only occurs when there is oblique incidence (the light ray strikes the interface at an angle other than 90 degrees) and different propagation speeds (the speed of light is different in each medium). This is because the change in angle and speed of the light ray as it enters a new medium causes it to bend, resulting in refraction.

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15. Which one of the following instruments is a component that stores digital echo signal information?

Explanation

A scan converter is an instrument that converts a video signal from one format to another. It takes input from a video source and stores the digital echo signal information in its memory. This allows the scan converter to manipulate and display the video signal in a different format, such as changing the resolution or aspect ratio. Therefore, the scan converter is the component that stores digital echo signal information.

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16. There have not been biological effects from US found in the laboratory.

Explanation

The statement suggests that there have been biological effects from US found in the laboratory. This means that there is evidence to support the claim that US (presumably ultrasound) has had an impact on biological systems in a laboratory setting. Therefore, the correct answer is False, indicating that there have been biological effects observed from US in the laboratory.

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17. The dB is defined as the _______________ of two intensities

Explanation

The dB is defined as the ratio of two intensities. It measures the relative difference between the two intensities, rather than their absolute values. This allows for a more convenient and standardized way of expressing the difference in power or amplitude between two signals.

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18. Which of the following is not a measure of area?

Explanation

Cubic meters is not a measure of area because it is a measure of volume. Area is a two-dimensional measurement that describes the amount of space an object or surface occupies, while volume is a three-dimensional measurement that describes the amount of space an object or substance occupies in all three dimensions. Therefore, cubic meters, which represents the volume of an object or substance, is not a measure of area.

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19. The wavelength of a cycle in an ultrasound wave can be reported with which units?

Explanation

Ultrasound waves are a type of mechanical wave that travels through a medium, such as air or water. The wavelength of a wave is the distance between two consecutive points that are in phase, or the distance over which the wave completes one full cycle. In the case of ultrasound waves, the wavelength is measured in units of distance, such as feet or centimeters. This is because the wavelength represents the physical length of the wave, indicating how far the wave travels in one complete cycle. Therefore, the correct answer is units of distance (feet, cm).

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20. If the frequency is decreased, the numberical value of the radial resolution is

Explanation

When the frequency is decreased, the numerical value of the radial resolution is increased. Radial resolution refers to the ability to distinguish two closely spaced objects along the radial axis. A higher numerical value indicates a greater ability to differentiate between these objects, meaning that the resolution is improved. Therefore, when the frequency is decreased, the radial resolution is increased.

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21. The more bits per pixel

Explanation

The more bits per pixel refers to the number of bits used to represent each pixel in an image. A higher number of bits allows for a greater range of shades of gray to be displayed. This means that the image will have more levels of gray between black and white, resulting in a more detailed and realistic representation of the image. Therefore, the statement "the more shades of gray" is the correct answer as it accurately reflects the relationship between the number of bits per pixel and the quality of the image.

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22. Which of the following will result in the greatest number of shades of gray in a digital image display?

Explanation

Large pixels with many bits per pixel will result in the greatest number of shades of gray in a digital image display. This is because larger pixels allow for more information to be captured and represented in each pixel, while having more bits per pixel increases the number of possible grayscale values that can be assigned to each pixel. Therefore, combining large pixels with many bits per pixel will result in a higher level of detail and a wider range of shades of gray in the image.

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23. What happens to the intensity of an ultrasound beam when the beam's cross-sectional area remains unchanged while the amplitude of the wave triples.

Explanation

When the amplitude of an ultrasound wave triples, the intensity of the ultrasound beam increases ninefold. This is because intensity is directly proportional to the square of the amplitude. Therefore, tripling the amplitude will result in the intensity being multiplied by 3^2, which equals 9.

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24. Which of the following sound waves is ultrasonic and least useful in diagnostic imaging?

Explanation

not-available-via-ai

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25. Circumferences are usually measured in:

Explanation

Circumferences are usually measured in centimeters (cm). This unit of measurement is commonly used to determine the length around the outer edge of a circular object or shape. It is a linear measurement that represents the distance around the circumference. The other options, such as cm squared (which is used for measuring area), cubic cm (which is used for measuring volume), and cubits (an ancient unit of measurement), are not typically used for measuring circumferences.

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26. The amplitude of an acoustic wave decreases from 27 pascals to 9 pascals.  If the initial power in the wave was 27 watts, what is the wave final power?

Explanation

The initial power in the wave is given as 27 watts. The amplitude of the wave decreases from 27 pascals to 9 pascals. The power of a wave is directly proportional to the square of its amplitude. Therefore, if the amplitude decreases by a factor of 3 (from 27 to 9), the power will decrease by a factor of 3 squared, which is 9. Therefore, the final power of the wave is 3 watts.

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27. What happens to an acoustic beams's intensity when the power in the beam increases by 25% while the cross sectional area of the beam remain the same?

Explanation

When the power in the acoustic beam increases by 25% while the cross-sectional area remains the same, the intensity of the beam also increases by 25%. This is because intensity is directly proportional to power, and since the power has increased by 25%, the intensity will also increase by the same percentage.

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28. _____________ is the distance covered by one cycle

Explanation

Wavelength is the distance covered by one cycle. It is a measure of the length between two consecutive points of a wave that are in phase. In other words, it represents the distance between two identical points on a wave, such as two crests or two troughs. Therefore, wavelength is the correct answer as it accurately describes the distance covered by one complete cycle of a wave.

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29. The more bits per pixel

Explanation

The correct answer is "the more shades of gray." This means that as the number of bits per pixel increases, the resolution improves, resulting in a higher pixel density. This allows for a greater range of shades of gray to be displayed, which ultimately leads to higher image quality and more accurate representation of colors and details. Additionally, having more shades of gray enhances the reliability of the image by reducing banding or color artifacts.

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30. What is the most typical Doppler shift measured clinically?

Explanation

The most typical Doppler shift measured clinically is 2kHz. The Doppler effect is used in medical imaging to measure blood flow velocity and direction. In this context, a Doppler shift of 2kHz indicates a moderate flow velocity, which is commonly observed in clinical settings. This frequency shift is within the range that can be easily detected and measured using Doppler ultrasound techniques.

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31. These substances exhibit a very slight negative or repelling effect when placed  in externally applied magnetic field.  They have low and negative suseptibility

Explanation

Diamagnetic substances are those that exhibit a very slight negative or repelling effect when placed in an externally applied magnetic field. This is due to the fact that the electrons in these substances are all paired up and their magnetic moments cancel out, resulting in a weak repulsion. Diamagnetic substances have low and negative susceptibility, meaning they are weakly repelled by magnetic fields.

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32. If we increase the frequency, the near zone length is

Explanation

When the frequency is increased, the near zone length is increased. The near zone refers to the region close to the source of the waves, where the wavefronts are not yet fully developed. As the frequency increases, the wavelength decreases, causing the wavefronts to become closer together. This results in a longer near zone length, as the waves take more time to fully develop and spread out. Therefore, increasing the frequency leads to an increased near zone length.

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33. These substances exhibit positive suseptibility , are stronger than paramagnetic substances, but are weaker than ferromagnetic substances, and are used as T2 contrast agents

Explanation

Superparamagnetic substances exhibit positive susceptibility, meaning they are attracted to a magnetic field. They are stronger than paramagnetic substances but weaker than ferromagnetic substances. Superparamagnetic substances are used as T2 contrast agents, which means they enhance the visibility of certain tissues or structures in medical imaging. Therefore, the correct answer is superparamagnetic.

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34. This type magnetic shielding uses metal, usually steel, in the scan room walls to contain the fringe field

Explanation

Passive magnetic shielding refers to the use of metal, typically steel, in the walls of the scan room to confine the fringe field. This type of shielding does not require any external power source or active control mechanisms. Instead, it relies on the inherent magnetic properties of the metal to redirect and absorb the magnetic field, preventing it from escaping the scan room. This passive approach is effective in containing the fringe field and minimizing its impact on the surrounding environment without the need for active interventions.

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35. All of the following will improve temporal resolution EXCEPT

Explanation

Increased line density refers to the number of scan lines used in an ultrasound image. The more scan lines there are, the higher the spatial resolution, which allows for better visualization of small structures. Therefore, increased line density will actually improve temporal resolution, as it allows for more frequent updates of the image over time. Therefore, the correct answer is "increased line density."

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36. All of the following statements reqarding in-vitro bioeffects are true EXCEPT

Explanation

In vitro bioeffects refer to the effects observed in biological systems outside of a living organism, such as in a laboratory setting. While in vitro bioeffects can provide valuable insights and information, the statement that "in vitro bioeffects conclusions are clinically relevant" is not entirely true. In vitro studies may not always accurately represent the complex and dynamic conditions found within a living organism, and therefore, the conclusions drawn from these studies may not directly translate to clinical settings. Clinical relevance is typically determined through in vivo studies, which involve testing in living organisms.

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37. Compare two sound waves. A and B.  The frequency of a wave A is one-third that of wave B.  How does the period of a wave A compare the period of wave B?

Explanation

The period of a wave is the time it takes for one complete cycle of the wave to occur. Since the frequency of wave A is one-third that of wave B, it means that wave A takes three times longer to complete one cycle compared to wave B. Therefore, the period of wave A is three times as long as the period of wave B.

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38. What componet of a transducer changes electrial to mechanical and mechanical back to electrical engery?

Explanation

PZT stands for lead zirconate titanate, which is a type of ceramic material commonly used in transducers. PZT is known for its piezoelectric properties, meaning it can convert electrical energy into mechanical energy and vice versa. In the context of a transducer, the PZT component is responsible for converting electrical signals into mechanical vibrations, which are then transmitted into the body or medium being imaged. These mechanical vibrations then bounce back and are converted back into electrical signals by the PZT, allowing the transducer to receive and detect echoes. Therefore, PZT is the component that changes electrical to mechanical and mechanical back to electrical energy in a transducer.

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39. Post processing occurs when the image

Explanation

Post processing occurs after the image has entered the A/D converter but before it is displayed. This means that the image goes through various adjustments and enhancements to improve its quality, such as noise reduction, color correction, sharpness, and contrast adjustments. These processes help to optimize the image for better visual perception and ensure that it appears as intended on the display device.

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40. What information does Doppler shift provide?

Explanation

Doppler shift provides information about the velocity of an object or wave. It is a phenomenon that occurs when there is a change in frequency or wavelength of a wave due to the relative motion between the source of the wave and the observer. By analyzing the Doppler shift, one can determine the velocity of the source or observer. Therefore, the correct answer is velocity.

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41. This type of magnetic shielding uses other magnets and their associated magnetic field to confine the field of the main magnet

Explanation

Active magnetic shielding refers to the use of additional magnets and their magnetic fields to contain or redirect the magnetic field of the main magnet. This technique actively manipulates the magnetic field to minimize its effects on the surrounding environment. By using active magnetic shielding, the main magnet's field can be confined and controlled more effectively compared to passive magnetic shielding, which relies on materials to block or absorb the magnetic field.

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42. What measures the output of the a transducer?

Explanation

A hydrophone is a transducer that measures the output of a transducer. It is specifically designed to detect and measure underwater sound waves, making it the most suitable option for measuring the output of a transducer in an underwater environment. A receiver is a general term and does not specifically measure the output of a transducer. A display is used to show information but does not directly measure the output. A hydrometer is used to measure the specific gravity or density of a liquid, so it is not the correct option for measuring the output of a transducer.

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43. Which type of artifact appears most commonly with highly reflective objects?

Explanation

Highly reflective objects tend to create strong contrasts between light and dark areas, resulting in the appearance of shadows. Shadowing is the process of casting shadows and is commonly observed with highly reflective objects. This occurs when the light source is blocked or partially blocked by the object, causing a shadow to be formed on the surface or surrounding area. Therefore, shadowing is the most common artifact that appears with highly reflective objects.

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44. Permanent magnets have field strengths of

Explanation

Permanent magnets have field strengths ranging from 0.06 to 0.35 Tesla (T). This means that the magnetic field produced by these magnets can have a strength between 0.06 T and 0.35 T. The range of field strengths is relatively low compared to other options, such as 1-3 T or up to 10 T, indicating that permanent magnets typically have weaker magnetic fields.

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45. Which transducer would be best to image superficial structures?

Explanation

A small diameter transducer with a high frequency would be best to image superficial structures. This is because a small diameter transducer can focus the ultrasound beam more precisely, allowing for better resolution of superficial structures. Additionally, a high frequency transducer can provide detailed images with better resolution, making it ideal for imaging shallow structures.

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46. How many decibels is related to 90% decrease in imaging power?

Explanation

this is a reduction to 1/10 of the original value

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47. The sonographer cannot change, directly or indirectly, the duty factor of an US machines.

Explanation

The duty factor of an ultrasound machine refers to the amount of time the machine is transmitting ultrasound waves compared to the total time it is on. This duty factor cannot be changed by the sonographer, either directly or indirectly. Therefore, the statement is false.

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48. Wires are aligned side by side to create magnet field

Explanation

A solenoid magnet is created by aligning wires side by side. When an electric current passes through these wires, a magnetic field is generated. The magnetic field created by a solenoid magnet is temporary and can be turned on or off by controlling the flow of electric current. This makes it different from a permanent magnet, which always produces a magnetic field, and a resistive magnet, which uses resistance to generate a magnetic field. Superconducting magnets, on the other hand, use superconducting materials to create a strong and constant magnetic field.

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49. Which of the following wave is ultrasonic and least useful in diagnotic ultrasound?

Explanation

Ultrasonic waves are sound waves with frequencies higher than the upper limit of human hearing, which is typically around 20 kHz. The given options include frequencies of 2 MHz, 2000 Hz, 24 kHz, and 7.5 MHz. Out of these options, 24 kHz is the only frequency that falls within the audible range of human hearing, making it least useful in diagnostic ultrasound. Diagnostic ultrasound typically utilizes frequencies in the range of 2 MHz to 15 MHz, which allows for better resolution and imaging of internal structures.

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50. The digital scan converter has a number of pixels assigned to each bit.

Explanation

The statement is false because a digital scan converter does not have pixels assigned to each bit. In a digital scan converter, pixels are assigned to each sample or data point, not to each bit. The number of pixels assigned to each sample or data point depends on the resolution of the scan converter.

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51. A sound wave leaves its source and travels through air.  The speed of sound in air is 330 m/sec.  One second later, an echo returns to the source.  At what distance from the source is the reflector that produced the echo?

Explanation

330/2 = 165

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52. Gadilinium is an example of a _ substance

Explanation

Gadolinium is an example of a paramagnetic substance because it has unpaired electrons in its atomic or molecular orbitals. Paramagnetic substances are weakly attracted to a magnetic field due to the presence of these unpaired electrons, which can align with the external field. This alignment causes a small magnetization in the substance, making it paramagnetic.

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53. Which of the following units are appropriate to describe the period of an acoustic wave?  More than one answer maybe correct.

Explanation

The period of an acoustic wave refers to the time it takes for one complete cycle of the wave. It is commonly measured in units of time, such as minutes and microseconds. These units are appropriate because they directly relate to the time it takes for the wave to complete a cycle. On the other hand, meters and mm/us are units of distance and velocity respectively, and do not directly describe the period of an acoustic wave.

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54. (TRUE OR FALSE) The power in the wave increases as it travels through the mass. (An ultrasound pulse propagates from soft tissue through a mass.  Sound's propagation speed in the mass is 1575 m/s.)

Explanation

False. The power in the wave does not increase as it travels through the mass. The power of a wave is determined by the amplitude of the wave, which does not change as the wave propagates through a medium. Therefore, the power of the wave remains constant regardless of the medium it travels through.

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55. Where are harmonics created?

Explanation

Harmonics are created in the tissue. When ultrasound waves pass through the tissue, they interact with the tissue structures and create harmonic frequencies. These harmonics are higher frequency waves that are multiples of the original ultrasound frequency. Harmonic imaging is used in ultrasound to improve image quality and reduce artifacts by selectively capturing and displaying these harmonics.

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56. Is Intensity an acoustic variable?

Explanation

Intensity is not an acoustic variable. Acoustic variables are properties that describe sound waves, such as frequency, wavelength, and amplitude. Intensity, on the other hand, is a measure of the power or energy carried by a sound wave per unit area. It is related to the amplitude of the wave but is not considered an acoustic variable itself. Therefore, the statement "Intensity is an acoustic variable" is false.

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57. Two waves arrive at the same location and interfere.  The resultant sound wave is smaller that either of the two original waves.  What is this called?

Explanation

Destructive interference occurs when two waves combine and their amplitudes cancel each other out, resulting in a smaller amplitude wave. This can happen when the peaks of one wave align with the troughs of the other wave, causing them to subtract from each other. In this case, the resultant sound wave is smaller than either of the two original waves, indicating destructive interference.

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58. If the frequency of US is increased from 0.77 MHz to 1.54 MHz, what happens to the wavelength?

Explanation

When the frequency of a wave increases, the wavelength decreases. This is because wavelength and frequency are inversely proportional to each other. Therefore, if the frequency of US is increased from 0.77 MHz to 1.54 MHz, the wavelength will be halved.

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59. The digital scan converter has a number of pixels assigned to each bit.

Explanation

The statement is false because the digital scan converter does not assign a specific number of pixels to each bit. A digital scan converter is a device that converts analog ultrasound signals into digital signals for display on a monitor. It does this by sampling the analog signal at regular intervals and assigning a binary value (bit) to each sample. The number of pixels in the display is determined by the resolution of the monitor, not by the number of bits in the digital scan converter.

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60. Which of the following will result in the highest mechanical index?

Explanation

A high mechanical index indicates a higher likelihood of cavitation, which is the formation and collapse of small bubbles in a liquid. Cavitation is typically desired in certain medical procedures, such as ultrasound imaging or therapy, as it can enhance the effects of the treatment. In this case, low frequency and high signal amplitude would result in the highest mechanical index because low frequency allows for better penetration into tissues, while high signal amplitude increases the likelihood of cavitation.

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61. With good images on the CRT but not on the strip chart recorder, one should

Explanation

If the images on the CRT (Cathode Ray Tube) are good but not on the strip chart recorder, it suggests that there may be an issue with the recorder itself. Adjusting the recorder may help to resolve the problem and improve the quality of the images.

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62. What may be a unit of amplitude?

Explanation

The unit of amplitude is typically measured in centimeters (cm). Amplitude refers to the maximum displacement or distance from the equilibrium position in a wave or oscillation. It is a measure of the intensity or strength of the wave and is usually represented by the height or depth of the wave. Therefore, cm is a suitable unit to measure the amplitude as it represents the distance or displacement.

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63. The frequency closest to the lower limits of US is:

Explanation

The frequency closest to the lower limits of the US is 15,000 Hz. This is because the given options include frequencies measured in kHz (kilohertz), MHz (megahertz), and msec (milliseconds), while the only option measured in Hz (hertz) is 15,000 Hz. Hertz is the standard unit for measuring frequency, and 15,000 Hz is the closest option to the lower limits of the US frequency range.

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64. Which of the following is not used to measure the output of ultrasound systems?

Explanation

A calibrated absorptiometer is not used to measure the output of ultrasound systems. An absorptiometer is a device used to measure the absorption of radiant energy by a substance, but it is not specifically designed or used for measuring ultrasound output. Ultrasound systems are typically measured using devices like hydrophones, thermocouples, calorimeters, and liquid crystals, which are specifically designed for this purpose.

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65. From a safety standpoint, which one of the following methods is best?

Explanation

From a safety standpoint, having a low transmitter output and high receiver gain is the best method. This ensures that the transmitter is not emitting a high amount of power, reducing the risk of potential hazards or interference. On the other hand, having a high receiver gain allows for better reception and amplification of the signal, improving the overall quality of communication without compromising safety.

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66. If the power in an ultrasound beam is unchanged, while at the same time, the beam area doubles, then the beams's intensity

Explanation

When the beam area doubles while the power remains the same, the intensity of the ultrasound beam is halved. Intensity is defined as power divided by area, so if the area increases while the power remains constant, the intensity decreases. In this case, since the area doubles, the intensity is halved.

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67. Magnets made of blocks or slabs or naturally occurring ferrous material.

Explanation

Permanent magnets are made of materials that retain their magnetism even after being removed from a magnetic field. These magnets can be made from blocks or slabs of ferrous material or naturally occurring magnetic materials. Unlike temporary magnets, permanent magnets do not require an external electrical current to generate a magnetic field. They are commonly used in various applications such as motors, generators, and speakers.

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68. According to the AIUM statement on bioeffects, there have been no confirmed bioeffects below intensities of __________ watts per square centimeter SPTA.

Explanation

According to the AIUM statement on bioeffects, there have been no confirmed bioeffects below intensities of 0.1 watts per square centimeter SPTA. This means that any ultrasound exposure below this intensity level has not been found to cause any harmful effects on biological tissues or organisms.

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69. Which of the following is true of all waves?

Explanation

All waves carry energy from one side to another. This is a fundamental characteristic of waves, regardless of the type of wave or the medium through which they travel. As waves propagate, they transfer energy without necessarily transferring matter. This is evident in various types of waves, such as sound waves, light waves, and water waves. The energy carried by waves can be observed through the effects they produce, such as the movement of particles, the sensation of sound or light, or the displacement of water.

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70. These coils utilize additional loops and circiutry to improve the efficiency with which the MR signal is induced in the coil, and increase SNR approximately 40% over the coil of the same size.

Explanation

Quadrature coils are designed with additional loops and circuitry to enhance the efficiency of the MR signal induction in the coil. These coils also increase the signal-to-noise ratio (SNR) by approximately 40% compared to coils of the same size. Therefore, the use of quadrature coils improves both the signal strength and quality in magnetic resonance imaging.

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71. These substances exhibit positive suseptibility, but when placed in an external magnetic field they will remain magnetized when external magnetic field is removed

Explanation

Ferromagnetic substances exhibit positive susceptibility, meaning they are attracted to a magnetic field. However, unlike paramagnetic and diamagnetic substances, ferromagnetic materials will remain magnetized even after the external magnetic field is removed. This is due to the presence of permanent magnetic domains within the material that align and create a strong magnetic field.

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72. The angle of incidence of an US beam is perpendicular to an interface.  The two media have the same propagation speeds.  What process cannot occur?

Explanation

When the angle of incidence of an ultrasound (US) beam is perpendicular to an interface and the two media have the same propagation speeds, the beam does not change direction as it passes through the interface. This means that there is no bending of the beam, which is the process of refraction. Therefore, the process that cannot occur in this scenario is refraction.

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73. Assuming a fixed frequency, what happens if the diameter of an ultrasound circular transducer is increased?

Explanation

When the diameter of an ultrasound circular transducer is increased, the beamwidth in the far field is reduced. This means that the ultrasound beam becomes more focused and narrower as it propagates further away from the transducer. This can be beneficial in applications where precise targeting or imaging is required. The reduction in beamwidth allows for improved resolution and better localization of the ultrasound energy in the far field.

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74. Substances that exhibit a slight increase in the magnetic field when placed in an externally applied magnetic field.  They have low and positive suseptibility.

Explanation

Paramagnetic substances are those that show a slight increase in their magnetic field when subjected to an external magnetic field. This behavior is due to the alignment of unpaired electrons in the presence of the external field. These substances have low and positive susceptibility, meaning that they are weakly attracted to the magnetic field. This is in contrast to diamagnetic substances, which are weakly repelled by the magnetic field, and ferromagnetic substances, which exhibit a strong attraction and can retain magnetism even after the external field is removed. Superparamagnetic is not a valid term and does not describe any specific magnetic behavior.

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75. Allow for increased area of coverage without the reduction in SNR, have multiple coils and receivers.

Explanation

A phase array allows for increased area of coverage without the reduction in SNR by having multiple coils and receivers. This means that the phase array system can receive and process signals from multiple directions simultaneously, allowing for a wider coverage area. The use of multiple coils and receivers also helps to maintain a high signal-to-noise ratio (SNR), which is crucial for accurate and reliable signal detection and processing. Therefore, a phase array system is an effective solution for achieving a larger coverage area without compromising on signal quality.

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76. How is range ambiguty artifact eliminated?

Explanation

Lowering the PRF (Pulse Repetition Frequency) eliminates range ambiguity artifact. Range ambiguity occurs when the ultrasound system is unable to distinguish between different echoes due to overlapping pulses. By lowering the PRF, the time between pulses increases, allowing for better separation of echoes and eliminating range ambiguity.

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77. If the output of an US machine is calibrated in dB and the output is increased by 20 dB, the beam intensity is increased

Explanation

When the output of a machine calibrated in dB is increased by 20 dB, the beam intensity is increased by a factor of 100. This is because the decibel scale is logarithmic, and a 20 dB increase corresponds to multiplying the intensity by 10 for each 10 dB increase. Therefore, a 20 dB increase results in a multiplication of 10^2, which equals 100.

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78. The maximum value of the density of an acoustic wave is 60 lb/in^2 while the minimum density is 20 lb/in^2.  What is the amplitude of the wave?

Explanation

The amplitude of a wave may be calculated by subracting the minimum value of the acoustic variable from its maximum and then dividing that number in half. In this case, the maximum minus the minimum is 60-20=40. Half of 40 is 20

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79. If the frame rate increases and the lines per frame is unchanged, what else must happen?

Explanation

If the frame rate increases and the lines per frame remain unchanged, it means that each frame is being displayed for a shorter duration of time. This results in a decrease in the depth perception because the brain has less time to process the visual information and create a sense of depth. Therefore, the depth decreases when the frame rate increases and the lines per frame is unchanged.

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80. Whichone of the following statements is true about a single pulse of ultrasound from a transducer?

Explanation

A single pulse of ultrasound from a transducer contains a range of frequencies. This is because the pulse is made up of different waves with varying frequencies. The transducer emits sound waves at different frequencies simultaneously, resulting in a pulse that contains a range of frequencies. This is important in ultrasound imaging as it allows for the detection of different structures and provides more detailed information about the object being examined.

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81. A force is applied to a surface.  If the force is tripled and the surface area over which the force is applied is also tripled, what is the new pressure?

Explanation

When the force applied to a surface is tripled and the surface area over which the force is applied is also tripled, the new pressure remains unchanged. This is because pressure is defined as force divided by surface area. When both the force and surface area are tripled, the ratio between them remains the same, resulting in an unchanged pressure.

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82. The power of an ultrasound wave can be reported with which of the following units? More than one answer maybe correct.

Explanation

The power of an ultrasound wave can be reported in watts because watts is the unit of power. Power is the rate at which energy is transferred or the amount of energy per unit time. Since ultrasound waves carry energy, their power can be measured in watts.

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83. What are the units of intensity?

Explanation

The units of intensity are typically measured in watts per square centimeter (watts/cm^2). Intensity refers to the amount of power per unit area, and watts/cm^2 is the appropriate unit to express this measurement. Watts alone do not account for the area over which the power is distributed, and watts/cm is not a valid unit for intensity as it does not include the squared term for area. dB (decibel) is a unit used to measure the relative intensity or power level of a sound or signal, but it is not the standard unit for intensity.

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84. Increasing the frequency increases the penetration depth.

Explanation

Increasing the frequency does not increase the penetration depth. In fact, higher frequencies result in decreased penetration depth. This is because higher frequencies have shorter wavelengths, which causes the energy to be absorbed and scattered more quickly as it interacts with the material being penetrated. As a result, lower frequencies are generally used when deeper penetration is required, such as in medical imaging or geological surveys.

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85. Ultrasound is defined as a sound with a frequency of

Explanation

Ultrasound refers to sound waves with frequencies higher than the upper limit of human hearing, which is typically around 20,000 Hz. The answer "greater than 0.02 MHz" is correct because 0.02 MHz is equivalent to 20,000 Hz. Therefore, any frequency higher than 0.02 MHz would fall within the ultrasound range.

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86. If the power of a sound wave is increased by a factor of 8 how many decibles is this?

Explanation

3dB means 2 times bigger 6dB is 3dB + 3dB. Therefore 6dB means 2 x 2 or 4 times bigger. Therefore 8 dB 2x2x2=8 or 3dB + 3dB + 3dB = 9 dB bigger

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87. Which of the following is associated with power mode Doppler?

Explanation

Power mode Doppler is a technique used in ultrasound imaging to detect and display blood flow. It is associated with poor temporal resolution because it requires multiple pulses to be transmitted and received to accurately measure blood flow. This results in a slower frame rate and reduced ability to capture rapid changes in blood flow. Additionally, power mode Doppler can produce a flash artifact, which is a bright signal that can obscure surrounding structures and make interpretation difficult. Therefore, the correct answer is poor temporal resolution and flash artifact.

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88. What is the actual time that an US machine is creating a pulse?

Explanation

The pulse duration refers to the actual time that a US (ultrasound) machine is creating a pulse. It measures the length of time that the pulse is being emitted from the machine. The duty factor, period, and pulse period are not directly related to the actual time of pulse creation, making them incorrect options.

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89. Under which circumstance is cavitation most likely to occur?

Explanation

Cavitation is most likely to occur under the circumstance of low frequency and high signal amplitude. Cavitation refers to the formation and collapse of vapor bubbles in a liquid due to rapid changes in pressure. Low frequency means that the pressure changes are occurring at a slower rate, allowing more time for the formation and collapse of vapor bubbles. High signal amplitude indicates a larger pressure difference, which can further facilitate the formation of vapor bubbles. Therefore, the combination of low frequency and high signal amplitude is the most conducive condition for cavitation to occur.

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90. A Doppler exam is performed with a 5MHz probe and a PRF of 15kHz.  Which of these Doppler shifts will create aliasing?

Explanation

not-available-via-ai

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91. As the impedances of two media become vastly different, the

Explanation

When the impedances of two media become vastly different, there is a greater difference in the way they transmit waves. This causes a larger portion of the wave to bounce back, resulting in an increase in reflection.

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92. An ultrasound system is set at 0 dB and is tranmitting at full intensity. What is the output power when the system is transmitting at 10% of full intensity?

Explanation

0 dB = full intensity 10% of full intensity would be negative or 1/10 or -10dB

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93. What is the minimum value of the duty factor?

Explanation

The minimum value of the duty factor is 0.0%. This means that the duty factor cannot be lower than 0.0%, indicating that there must be some amount of duty or activity within a given time period. A duty factor of 0.0% would imply that there is no activity or duty being performed, resulting in a complete absence of any work or task.

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94. The dynamic range of the receiver of an ultrasound instrument refers to the

Explanation

The dynamic range of the receiver of an ultrasound instrument refers to the range of echo signal amplitudes that can be processed without distortion. This means that the receiver is able to accurately detect and process a wide range of echo signal strengths without losing any important information or introducing any unwanted distortions. This is an important characteristic of the receiver as it allows for the detection and analysis of both weak and strong echo signals, providing a more comprehensive and accurate ultrasound image.

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95. Require the use of solenoid coils due to the orientation of the B0, more effiecient than linear coil, and can be combine with other coils electronically to improve signal uniformity through a region of interest.

Explanation

The use of solenoid coils is required in the vertical configuration because the orientation of the B0 magnetic field is vertical. This orientation allows for more efficient signal generation and reception compared to linear coils. Additionally, vertical coils can be electronically combined with other coils, such as phased array coils, to improve the uniformity of the signal throughout the region of interest.

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96. 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% of full intensity?

Explanation

50% of full intensity is 1/2. 0 dB is full intensity so -3dB would be half

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97. An amplifier of an ultrasound system increases the voltage of a signal from 0.0001 to 0.1 volt.  What is the amplification?

Explanation

The amplification is 60 dB. Decibels (dB) is a logarithmic unit used to express the ratio of two values. In this case, the ratio of the final voltage (0.1 volt) to the initial voltage (0.0001 volt) is calculated. By taking the logarithm of this ratio and multiplying it by 10, we get the amplification in decibels. In this case, the amplification is 60 dB.

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98. When the power in an acoustic beam is doubled and the cross sectional area of the beam is halved, then the intensity of the beam is

Explanation

When the power in an acoustic beam is doubled, it means that the amount of energy transmitted by the beam has increased. However, when the cross-sectional area of the beam is halved, it means that the same amount of energy is now spread over a smaller area. This results in a higher concentration of energy, leading to an increased intensity of the beam. Therefore, the intensity of the beam is four times larger than before.

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99. With normal incidence, what factors affect refraction of US?

Explanation

The refraction of ultrasound is not affected by any of the factors listed. Refraction occurs when a wave passes from one medium to another with a different propagation speed. However, with normal incidence, the ultrasound wave travels straight through the interface without changing direction, so the propagation speeds of the media do not come into play. Similarly, the frequency and attenuation coefficients of the ultrasound wave do not affect its refraction in this scenario. Therefore, none of the factors listed have an impact on the refraction of ultrasound with normal incidence.

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100. The final amplitude of an acoustic wave is reduced to one-half of its original value.  The final power is _______ the original power.

Explanation

Changes in the power of a wave are proportional to changes in the waves amplitude squared. 1/2 squared = 1/4 (1/2 + 1/2 = 1/4) When 1/2 of the wave's original amplitude remains, then only 1/4 of the original power remains.

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What determines the frequency of a sound beam from a pulsed...
Shadowing may result from high amounts of reflection of US energy.
10000 gauss = _ Tesla
Which has the greatest amount of attenuation?
True of False:  With standard diagnostic imaging instrumentation,...
What happens to venous blood flow to the heart during expiration?
For Doppler, which incident angle reults in no shift?
Decimal uses a base of 10, binary uses a base of
What determines the intensity of an ultrasound beam after it has...
Which of the following terms best describes the relationship between...
If the frequency is decreased, the numerical value of the radial...
Which of the following has a propagation speed closest to "soft...
What is displayed on the y axis of an m-mode image?
Refraction only occurs if there is :
Which one of the following instruments is a component that stores...
There have not been biological effects from US found in the...
The dB is defined as the _______________ of two intensities
Which of the following is not a measure of area?
The wavelength of a cycle in an ultrasound wave can be reported with...
If the frequency is decreased, the numberical value of the radial...
The more bits per pixel
Which of the following will result in the greatest number of shades of...
What happens to the intensity of an ultrasound beam when the beam's...
Which of the following sound waves is ultrasonic and least useful in...
Circumferences are usually measured in:
The amplitude of an acoustic wave decreases from 27 pascals to 9...
What happens to an acoustic beams's intensity when the power in the...
_____________ is the distance covered by one cycle
The more bits per pixel
What is the most typical Doppler shift measured clinically?
These substances exhibit a very slight negative or repelling effect...
If we increase the frequency, the near zone length is
These substances exhibit positive suseptibility , are stronger...
This type magnetic shielding uses metal, usually steel, in the scan...
All of the following will improve temporal resolution EXCEPT
All of the following statements reqarding in-vitro bioeffects are true...
Compare two sound waves. A and B.  The frequency of a wave A is...
What componet of a transducer changes electrial to mechanical and...
Post processing occurs when the image
What information does Doppler shift provide?
This type of magnetic shielding uses other magnets and their...
What measures the output of the a transducer?
Which type of artifact appears most commonly with highly reflective...
Permanent magnets have field strengths of
Which transducer would be best to image superficial structures?
How many decibels is related to 90% decrease in imaging power?
The sonographer cannot change, directly or indirectly, the duty factor...
Wires are aligned side by side to create magnet field
Which of the following wave is ultrasonic and least useful in...
The digital scan converter has a number of pixels assigned to each...
A sound wave leaves its source and travels through air.  The...
Gadilinium is an example of a _ substance
Which of the following units are appropriate to describe the period of...
(TRUE OR FALSE) The power in the wave increases as it travels through...
Where are harmonics created?
Is Intensity an acoustic variable?
Two waves arrive at the same location and interfere.  The...
If the frequency of US is increased from 0.77 MHz to 1.54 MHz, what...
The digital scan converter has a number of pixels assigned to each...
Which of the following will result in the highest mechanical index?
With good images on the CRT but not on the strip chart recorder, one...
What may be a unit of amplitude?
The frequency closest to the lower limits of US is:
Which of the following is not used to measure the output of ultrasound...
From a safety standpoint, which one of the following methods is best?
If the power in an ultrasound beam is unchanged, while at the same...
Magnets made of blocks or slabs or naturally occurring ferrous...
According to the AIUM statement on bioeffects, there have been no...
Which of the following is true of all waves?
These coils utilize additional loops and circiutry to improve the...
These substances exhibit positive suseptibility, but when placed in an...
The angle of incidence of an US beam is perpendicular to an...
Assuming a fixed frequency, what happens if the diameter of an...
Substances that exhibit a slight increase in the magnetic field when...
Allow for increased area of coverage without the reduction in SNR,...
How is range ambiguty artifact eliminated?
If the output of an US machine is calibrated in dB and the output is...
The maximum value of the density of an acoustic wave is 60 lb/in^2...
If the frame rate increases and the lines per frame is unchanged, what...
Whichone of the following statements is true about a single pulse of...
A force is applied to a surface.  If the force is tripled and the...
The power of an ultrasound wave can be reported with which of the...
What are the units of intensity?
Increasing the frequency increases the penetration depth.
Ultrasound is defined as a sound with a frequency of
If the power of a sound wave is increased by a factor of 8 how many...
Which of the following is associated with power mode Doppler?
What is the actual time that an US machine is creating a pulse?
Under which circumstance is cavitation most likely to occur?
A Doppler exam is performed with a 5MHz probe and a PRF of...
As the impedances of two media become vastly different, the
An ultrasound system is set at 0 dB and is tranmitting at full...
What is the minimum value of the duty factor?
The dynamic range of the receiver of an ultrasound instrument refers...
Require the use of solenoid coils due to the orientation of the B0,...
An ultrasound system is set at 0 dB and is transmitting at full...
An amplifier of an ultrasound system increases the voltage of a signal...
When the power in an acoustic beam is doubled and the cross sectional...
With normal incidence, what factors affect refraction of US?
The final amplitude of an acoustic wave is reduced to one-half of its...
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