1.
Attenuation rate in the human body (roundtrip)
Correct Answer
A. 1 dB/cm/MHz
Explanation
The correct answer is 1 dB/cm/MHz. This means that the attenuation rate in the human body is 1 decibel per centimeter per megahertz. Attenuation refers to the decrease in intensity or power of a signal as it travels through a medium. In this case, it is referring to the rate at which ultrasound waves are absorbed or scattered in the human body. A higher attenuation rate indicates that the ultrasound waves are being absorbed or scattered more rapidly, resulting in a decrease in their intensity.
2.
Which of the following will happen if the ultrasound wave travels through the medium at 90 degrees perpendicular to the object?
Correct Answer
B. More ultrasound echoes will be picked up by the receiver
Explanation
When an ultrasound wave travels through a medium at 90 degrees perpendicular to the object, more ultrasound echoes will be picked up by the receiver. This is because when the wave is perpendicular to the object, it will bounce back and forth multiple times between the object and the medium, creating more echoes. These echoes will then be detected by the receiver, resulting in more ultrasound echoes being picked up.
3.
It is the sound beam that comes from structures that throw back the sound beam they have intercepted.
Correct Answer
D. All of the above
Explanation
The correct answer is "All of the above". This is because all three options - reflected beam, resonating beam, and echo - can be explanations for the sound beam that comes from structures that throw back the sound beam they have intercepted. A reflected beam occurs when the sound wave bounces off a surface, a resonating beam is produced when the sound wave causes a structure to vibrate and emit sound, and an echo is the reflection of sound off a surface that is heard again. Therefore, all three options can be valid explanations for the given statement.
4.
Red Blood Cells are the major specular reflectors in the human body.
Correct Answer
B. False
Explanation
Red blood cells are not the major specular reflectors in the human body. Specular reflectors refer to surfaces that reflect light in a specific direction, like a mirror. While red blood cells do reflect some light, they are not the primary reflectors in the body. Other tissues and structures, such as bones and organs, have a higher reflectivity and contribute more to specular reflection. Therefore, the statement is false.
5.
which of the following statements describes reflection?
I.the amount of reflected energy depends on the difference in the acoustic impedance of the two media through which ultrasound passes.II.it is the bending of a wave when it passes through a medium with different densities.III. bouncing back of the wave as it interacts with structures along its path.
Correct Answer
B. I and III
Explanation
Reflection in the context of ultrasound refers to the bouncing back of the wave as it interacts with structures along its path. This is described in statement III. Additionally, the amount of reflected energy depends on the difference in the acoustic impedance of the two media through which ultrasound passes, which is described in statement I. Therefore, the correct answer is I and III.
6.
A reflector that is small compared to the wavelength of the transmitted frequency will produce,
Correct Answer
D. Rayleigh scattering
Explanation
When a reflector is small compared to the wavelength of the transmitted frequency, it will produce Rayleigh scattering. Rayleigh scattering occurs when the size of the scattering object is much smaller than the wavelength of the incident radiation. In this case, the small reflector causes the transmitted frequency to scatter in various directions, resulting in the phenomenon of Rayleigh scattering. This scattering is responsible for the blue color of the sky during the day and the reddening of the sun during sunrise and sunset.
7.
Reflection at the tissue interface depends primarily on
Correct Answer
A. Impedance
Explanation
The reflection at the tissue interface primarily depends on impedance. Impedance is a measure of the resistance to the flow of sound waves in a medium. When sound waves encounter a tissue interface with different impedance values, some of the waves are reflected back. The amount of reflection depends on the difference in impedance between the two tissues. Therefore, impedance plays a crucial role in determining the amount of reflection at tissue interfaces.
8.
Velocity times density equals
Correct Answer
A. Impedance
Explanation
The equation "velocity times density equals impedance" is a fundamental relationship in physics and acoustics. Impedance is a measure of how much a medium resists the flow of energy. In the context of sound waves, velocity refers to the speed at which the waves travel through a medium, while density refers to how closely packed the particles in the medium are. When these two factors are multiplied together, they give the impedance of the medium, which determines how much sound energy is reflected or transmitted at a boundary between different mediums.
9.
The degree of attenuation is dependent on
Correct Answer
D. Frequency and distance
Explanation
Attenuation refers to the reduction in the strength of a signal as it travels through a medium. The degree of attenuation is influenced by two factors: frequency and distance. Frequency affects attenuation because different frequencies have different levels of absorption and scattering in the medium. Higher frequencies tend to experience more attenuation. Distance also plays a role as the signal weakens over longer distances due to factors like spreading and absorption. Therefore, the correct answer is frequency and distance.
10.
What is scattering?
Correct Answer
B. Redirection of sound beam in many directions
Explanation
Scattering refers to the phenomenon where a sound beam is redirected in many directions. This means that instead of the sound beam traveling in a straight line, it is dispersed or scattered in various directions. This can occur when sound waves encounter obstacles or irregularities in the medium through which they are traveling. As a result, the sound energy is spread out and dispersed in different directions, causing the sound beam to be redirected.