Rt Simulation Examination 4
This is a Simulated Examination for Gulf RT Examinations taken from Last Month's HAAD Feedbacks.
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Take this examination for 120 minutes. You need to get 86% to pass the HAAD. 60% to pass MOH, DHA, or Prometrics.
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Questions and Answers
- 1.
The receiver gandwidth represents the range of frequencies sampled during the
- A.
Phase gradient
- B.
Slice selection gradient
- C.
Frequency encoding gradient
- D.
Gradient coils
Correct Answer
C. Frequency encoding gradientExplanation
The frequency encoding gradient is responsible for encoding the spatial information along the frequency axis in magnetic resonance imaging (MRI). It determines the range of frequencies that are sampled during the imaging process. By varying the strength and duration of the gradient, different frequencies can be encoded, allowing for the creation of a spatial map of the object being imaged. Therefore, the receiver bandwidth represents the range of frequencies sampled during the frequency encoding gradient.Rate this question:
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- 2.
The receiver bandwidth is determined by the number of
- A.
Phase steps in the martrix
- B.
Frequency samples in the matrix
Correct Answer
B. Frequency samples in the matrixExplanation
The receiver bandwidth is determined by the number of frequency samples in the matrix. This means that the more frequency samples there are in the matrix, the wider the receiver bandwidth will be. This is because each frequency sample represents a specific frequency range that the receiver can detect. Therefore, a larger number of frequency samples allows the receiver to detect a wider range of frequencies, resulting in a broader bandwidth.Rate this question:
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- 3.
If 256 frequency samples are collected and the readout or sampling period is 8 ms, the receiver bandwidth would be
Correct Answer
16 KhzExplanation
The receiver bandwidth can be calculated by dividing the number of frequency samples (256) by the sampling period (8 ms). In this case, 256 divided by 8 ms equals 32 kHz. However, since the Nyquist-Shannon sampling theorem states that the maximum frequency that can be accurately represented is half of the sampling rate, the receiver bandwidth would be half of 32 kHz, which is 16 kHz.Rate this question:
- 4.
The main purpose of the gradient subsystem is to
- A.
Select the slice plane
- B.
Select the imaging plance
- C.
Spatially encode the MR signal
- D.
All of the above
Correct Answer
D. All of the aboveExplanation
The gradient subsystem in MRI plays multiple roles. Firstly, it helps in selecting the slice plane by applying gradients in different directions. Secondly, it assists in selecting the imaging plane by applying gradients along specific axes. Lastly, it spatially encodes the MR signal by applying gradients with varying strengths across the imaging plane. Therefore, the correct answer is "all of the above" as the gradient subsystem serves all these purposes.Rate this question:
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- 5.
This gradient coil varies the intensity of the magnetic field in the head to foot direction
- A.
X
- B.
Y
- C.
Z
Correct Answer
C. ZExplanation
The gradient coil in the z direction is responsible for varying the intensity of the magnetic field in the head to foot direction. This means that the strength of the magnetic field can be adjusted along the z-axis, which is the vertical axis from head to foot. This is important in magnetic resonance imaging (MRI) as it allows for the spatial encoding of the image, enabling the differentiation of tissues and the creation of detailed images.Rate this question:
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- 6.
This gradient coil varies the intensity of the magnetic field in the right to left direction
- A.
X
- B.
Y
- C.
Z
Correct Answer
A. XExplanation
The correct answer is x because the gradient coil is responsible for creating a varying magnetic field in different directions. In this case, it specifically varies the intensity of the magnetic field in the right to left direction. The x-axis is the horizontal axis in the Cartesian coordinate system, and it represents the right to left direction. Therefore, the gradient coil along the x-axis would be able to achieve the desired variation in magnetic field intensity.Rate this question:
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- 7.
A way to express the gradient performance referring to the acceleration of the gradient magnetic field to its maximum amplitude, expressed in units of T/m/s.
- A.
Rise time
- B.
Coil configuration
- C.
Slew rate
Correct Answer
C. Slew rateExplanation
The term "slew rate" refers to the rate at which the gradient magnetic field increases to reach its maximum amplitude. It is measured in units of T/m/s, which stands for tesla per meter per second. The slew rate indicates how quickly the gradient magnetic field can change, and a higher slew rate generally implies better performance in terms of acceleration. Therefore, in the given context, the correct answer is "slew rate."Rate this question:
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- 8.
THE DIFFERENCE IN PRECESSIONAL FREQUENCY OF THE HYDROGEN IN FAT AND WATER IS KNOWN AS
- A.
FOURIER TRANSFORM
- B.
FID
- C.
SPIN DENSITY
- D.
CHEMICAL SHIFT
Correct Answer
D. CHEMICAL SHIFTExplanation
The difference in precessional frequency of the hydrogen in fat and water is known as the chemical shift. Chemical shift is a phenomenon in nuclear magnetic resonance (NMR) spectroscopy where the resonance frequency of a particular nucleus is influenced by the chemical environment it is in. In the case of hydrogen, the chemical shift is caused by the surrounding electron density and magnetic shielding effects. By measuring the chemical shift, scientists can gain valuable information about the molecular structure and composition of a sample.Rate this question:
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- 9.
WHEN IS THE SLICE SELECTION GRADIENT APPLIED
- A.
DURING THE ECHO
- B.
DURING THE 90 DEGREE RF PULSE
- C.
AFTER THE 180 DEGREE RF PULSE
- D.
DURING THE 90 AND 180 DEGREE RF PULSE
Correct Answer
D. DURING THE 90 AND 180 DEGREE RF PULSEExplanation
The slice selection gradient is applied during the 90 and 180 degree RF pulse. This is because the slice selection gradient is used to spatially encode the signal from a specific slice in the imaging plane. The 90 degree RF pulse is responsible for flipping the magnetization vector into the transverse plane, while the 180 degree RF pulse is responsible for refocusing the magnetization vector. Therefore, the slice selection gradient is applied during these RF pulses to select the desired slice for imaging.Rate this question:
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- 10.
THE PHASE ENCODING GRADIENT REPRESENTS
- A.
THE AMOUNT OF TIMES THE ECHO IS SAMPLED
- B.
THE LINE IN K SPACE ON WHICH THE DATA WILL BE PLOTTED DURING THE READOUT PERIOD
- C.
THE AMOUNT OF RESOLUTION IN THE IMAGE
Correct Answer
B. THE LINE IN K SPACE ON WHICH THE DATA WILL BE PLOTTED DURING THE READOUT PERIODExplanation
The phase encoding gradient represents the line in k-space on which the data will be plotted during the readout period. K-space is a mathematical representation of the spatial frequency domain in MRI. The phase encoding gradient is applied during the data acquisition process to encode spatial information along a specific direction. By varying the strength and timing of the phase encoding gradient, different lines in k-space are sampled, allowing for the reconstruction of the image with different levels of resolution.Rate this question:
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- 11.
IF A THICKER SLICE IS DESIRED
- A.
A LOWER AMPLITUDE OF THE Y GRADIENT IS SELECTED
- B.
A HIGHER AMPLITUDE OF THE Z GRADIENT IS SELECTED
- C.
A HIGHER AMPLITUDE OF THE X GRADIENT IS SELECTED
- D.
A LOWER AMPLITUDE OF THE Z GRADIENT IS SELECTED
Correct Answer
D. A LOWER AMPLITUDE OF THE Z GRADIENT IS SELECTEDExplanation
To obtain a thicker slice, a lower amplitude of the Z gradient is selected. The Z gradient is responsible for the slice thickness in magnetic resonance imaging (MRI). By reducing the amplitude of the Z gradient, the magnetic field variation in the Z direction is decreased, resulting in a thicker slice being excited during the imaging process.Rate this question:
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- 12.
THE ONLY WAY THE SPATIAL RESOLUTION CAN INCREASED IS TO
- A.
INCREASE THE FOV
- B.
DECREASE THE PHASE ENCODINGS OF THE MATRIX
- C.
INCREASE THE VOXEL VOLUME
- D.
REDUCE THE VOXEL VOLUME
Correct Answer
D. REDUCE THE VOXEL VOLUMEExplanation
The question is asking for the only way to increase spatial resolution. Spatial resolution refers to the level of detail that can be seen in an image. To increase spatial resolution, the voxel volume needs to be reduced. Voxel volume refers to the size of the 3D pixels that make up the image. By reducing the voxel volume, the pixels become smaller and more closely packed together, allowing for a higher level of detail and increased spatial resolution. Increasing the FOV (field of view) would not directly affect spatial resolution, and decreasing the phase encodings of the matrix would actually decrease the amount of information captured, resulting in lower spatial resolution.Rate this question:
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- 13.
Family members and ancilliary personnell accompanying the patient into the scan room :
- A.
Need not to be screened because they are not undergoing an MRI
- B.
Should be screened as if they are going through the procedure themselves
- C.
Must wear a lead apron during the procedure
Correct Answer
B. Should be screened as if they are going through the procedure themselvesExplanation
Family members and ancillary personnel accompanying the patient into the scan room should be screened as if they are going through the procedure themselves. This is because they will be in close proximity to the MRI machine, which can generate strong magnetic fields. Screening them helps to ensure their safety and identify any potential risks or contraindications that may affect their presence in the scan room. It is important to prioritize the well-being of all individuals present during the MRI procedure.Rate this question:
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- 14.
A component used to increasze the strength of a signal
- A.
Gradient coil
- B.
Equipment cabinet
- C.
Digital to analog converter
- D.
Amplifier
Correct Answer
D. AmplifierExplanation
An amplifier is a component used to increase the strength of a signal. It takes a weak input signal and boosts it to a higher level, allowing it to be transmitted or processed more effectively. Amplifiers are commonly used in audio systems, telecommunications, and many other applications where signal strength needs to be enhanced.Rate this question:
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- 15.
The link between the technologist and the computerized electronic environment of the MR system hardware
- A.
Equipment room
- B.
Equipment cabinet
- C.
Operator's console
- D.
Gradient amplifiers
Correct Answer
C. Operator's consoleExplanation
The operator's console is the link between the technologist and the computerized electronic environment of the MR system hardware. It serves as the control center where the technologist can interact with the MR system and make necessary adjustments during the scanning process. The console allows the technologist to input patient information, select scanning parameters, monitor the progress of the scan, and make any necessary changes or interventions. It provides a user-friendly interface for the technologist to effectively operate the MR system and ensure the quality and safety of the imaging procedure.Rate this question:
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- 16.
The operators may be used for:1. converting digital to analog 2. viewing images3. archiving images
- A.
1 and 2
- B.
1 and 3
- C.
2 and 3
- D.
1, 2, and 3
Correct Answer
C. 2 and 3Explanation
The correct answer is 2 and 3 because the operators can be used for viewing images and archiving images. Converting digital to analog is not mentioned as one of the uses for the operators.Rate this question:
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- 17.
The pulse sequence controller is located
- A.
Inside the magnet
- B.
In the operator's console
- C.
On an rf coil
- D.
In the equipment cabinet
Correct Answer
D. In the equipment cabinetExplanation
The pulse sequence controller, which is responsible for controlling the timing and sequence of radiofrequency pulses in an imaging system, is located in the equipment cabinet. This is where all the necessary components and electronics for the system are housed, including the pulse sequence controller. Placing it in the equipment cabinet allows for easy access and maintenance, as well as efficient communication with other system components.Rate this question:
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- 18.
The __ is located within an equipment cabinet
- A.
Magnetic shielding
- B.
RF power amplifier
- C.
Gradient coils
- D.
Rf coils
Correct Answer
B. RF power amplifierExplanation
The RF power amplifier is located within an equipment cabinet. This is because the RF power amplifier is responsible for amplifying the radio frequency signals used in various applications such as wireless communication or broadcasting. By placing it within an equipment cabinet, it helps to protect the amplifier from external interference, provides a controlled environment for operation, and allows for easy access and maintenance.Rate this question:
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- 19.
The host computer
- A.
Is the interface between the technologist and the MR system
- B.
Constrains the fringe magnetic field to a smaller space
- C.
Digitizes the MR echoes
- D.
Reconstructs the MR images
Correct Answer
A. Is the interface between the technologist and the MR systemExplanation
The host computer serves as the intermediary between the technologist and the MR system. It allows the technologist to interact with and control the MR system, providing a user-friendly interface. Additionally, the host computer is responsible for constraining the fringe magnetic field to a smaller space, ensuring the safety of the technologist and patients. It also digitizes the MR echoes, converting them into a digital format for further processing. Lastly, the host computer plays a crucial role in reconstructing the MR images, utilizing advanced algorithms to transform the digitized data into meaningful images.Rate this question:
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- 20.
The _ is responsible for telling the gradients when and at what strength to turn on
- A.
Magnetic shielding
- B.
Pulse sequence controller
- C.
Rf power amplifier
- D.
Host computer
Correct Answer
B. Pulse sequence controllerExplanation
The pulse sequence controller is responsible for telling the gradients when and at what strength to turn on. This controller is an essential component in magnetic resonance imaging (MRI) systems, as it determines the timing and sequencing of the magnetic field gradients. By controlling the gradients, the pulse sequence controller ensures that the correct spatial and temporal information is obtained during the imaging process.Rate this question:
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- 21.
The _ provides the elctrical power to the gradient coils
- A.
Pulse sequence controller
- B.
Rf power amplifier
- C.
Gradient power amplifier
- D.
Host computer
Correct Answer
C. Gradient power amplifierExplanation
The gradient power amplifier is responsible for providing electrical power to the gradient coils. These coils are an essential component of an MRI system and are used to create the gradient magnetic fields necessary for spatial encoding and image formation. The gradient power amplifier amplifies the electrical signals generated by the pulse sequence controller and supplies them to the gradient coils, allowing for precise control and adjustment of the magnetic field gradients during the imaging process.Rate this question:
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- 22.
The _ provides the electrical power to the gradient coils
- A.
Pulse sequence controller
- B.
Rf power amplifier
- C.
Gradient power amplifier
- D.
Host computer
Correct Answer
C. Gradient power amplifierExplanation
The gradient power amplifier is responsible for providing the electrical power to the gradient coils. The gradient coils are an essential component of magnetic resonance imaging (MRI) systems and are used to generate the magnetic field gradients necessary for spatial encoding of the MRI signal. The gradient power amplifier amplifies the electrical signals from the pulse sequence controller and delivers the required power to the gradient coils, allowing for precise control and manipulation of the magnetic field.Rate this question:
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- 23.
On a sagittal image which of the following would be affected if the gradient power amplifier for the x gradient coil malfuctioned and produced a gradient in the magnetic field of twice the prescribed strength
- A.
Thickness of the slice
- B.
Field of view of the slice
- C.
Image orientation
- D.
Image matrix
Correct Answer
A. Thickness of the sliceExplanation
If the gradient power amplifier for the x gradient coil malfunctions and produces a gradient in the magnetic field of twice the prescribed strength, it would affect the thickness of the slice. The gradient strength determines the thickness of the slice in magnetic resonance imaging (MRI). A stronger gradient would result in a thicker slice being imaged. Therefore, if the gradient power amplifier malfunctioned and produced a gradient twice as strong as prescribed, the thickness of the slice would be affected.Rate this question:
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- 24.
Upon installing a new MRI system, the service engineer mistakenly connects the x-gradient power amplifier to the y-gradient coil, the y-gradient power amplifier to the z-gradient coil, and the z-gradient power amplifier to the x-gradient coil. A __ image would result when the technologist runs the first transverse sequence.
- A.
Tranverse
- B.
Oblique
- C.
Coronal
- D.
Sagittal
Correct Answer
D. SagittalExplanation
When the x-gradient power amplifier is connected to the y-gradient coil, the y-gradient power amplifier is connected to the z-gradient coil, and the z-gradient power amplifier is connected to the x-gradient coil, it results in a misalignment of the gradients in the MRI system. This misalignment causes the magnetic field to be applied in the wrong direction during the transverse sequence. As a result, the image obtained will be sagittal, which refers to a slice taken from the left to right or right to left direction of the body.Rate this question:
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- 25.
The RF shielding: 1. prevents the RF energy generated by the MR system from disturbing external radio signals2. restricts external radio signals from being detected 3. prevents RF related artifacts from resulting
- A.
1and 3
- B.
1 and 2
- C.
1, 2, and 3
- D.
2 and 3
Correct Answer
C. 1, 2, and 3Explanation
The RF shielding serves multiple purposes. Firstly, it prevents the RF energy generated by the MR system from disturbing external radio signals. This is important to ensure that the MR system does not interfere with other electronic devices or communication systems. Secondly, it restricts external radio signals from being detected by the MR system. This is necessary to prevent any external interference from affecting the quality of the MR images. Lastly, the RF shielding also helps in preventing RF related artifacts from resulting in the images. These artifacts can distort the images and affect their diagnostic accuracy. Therefore, all three statements are correct and the correct answer is 1, 2, and 3.Rate this question:
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- 26.
A measure of the uniformity of the magnetic field of the system is a defintion of
- A.
Cryogen
- B.
Homogeneity
- C.
Quadrature
- D.
Precession
Correct Answer
B. HomogeneityExplanation
Homogeneity refers to the uniformity of the magnetic field in a system. A measure of homogeneity indicates how consistent the magnetic field is throughout the system. In other words, it measures the degree to which the magnetic field strength and direction remain constant across different points within the system. Therefore, homogeneity is the correct answer as it directly relates to the uniformity of the magnetic field.Rate this question:
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- 27.
Which of the following is the defintion of shimming
- A.
Adjusting homogeneity of the magnetic field
- B.
Creating a linear change in the magnetic field
- C.
Confining the magnetic field to a smaller arfea
- D.
Rapidly shutting off the magnetic field
Correct Answer
A. Adjusting homogeneity of the magnetic fieldExplanation
Shimming refers to the process of adjusting the homogeneity of the magnetic field. This is typically done in magnetic resonance imaging (MRI) to ensure that the magnetic field is uniform and stable throughout the imaging process. By making small adjustments, such as adding or removing shims, the magnetic field can be fine-tuned to minimize any distortions or variations that may affect the quality of the MRI images. Therefore, shimming plays a crucial role in optimizing the performance and accuracy of MRI scans.Rate this question:
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- 28.
__ magnets must be taken apart in order to shut off the magnetic field
- A.
Permanent
- B.
Superconducting
- C.
Electro
- D.
Resistive
Correct Answer
A. PermanentExplanation
Permanent magnets must be taken apart in order to shut off the magnetic field because they are made from materials that have their own magnetic properties. These materials, such as iron, nickel, and cobalt, are magnetized and retain their magnetic field even when not in contact with a magnetic field. This is different from other types of magnets, such as electromagnets, which require an external power source to generate a magnetic field.Rate this question:
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- 29.
Which of the following describes an electromagnet
- A.
Magnetic bricks are stacked together to form the magnet
- B.
Electrical current flows through a coil of wire and generates a magnetic field
- C.
A changing magnetic field around a coil of wire generates an electic field
- D.
A moving magnetic field induces an electrical current in a neighboring conductive material
Correct Answer
B. Electrical current flows through a coil of wire and generates a magnetic fieldExplanation
An electromagnet is created when an electrical current flows through a coil of wire, which generates a magnetic field. This magnetic field is temporary and can be turned on or off by controlling the flow of electricity. Unlike a permanent magnet, an electromagnet can be adjusted and manipulated, making it useful in various applications such as electric motors, generators, and magnetic separation devices.Rate this question:
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- 30.
__ magnets must remain connected to a power source to maintain their magnetc field.
- A.
Resistive
- B.
Permanent
- C.
Superconducting
- D.
Bar
Correct Answer
A. ResistiveExplanation
Resistive magnets must remain connected to a power source to maintain their magnetic field because they rely on the flow of electrical current through a resistive material to generate the magnetic field. Once the power source is disconnected, the flow of current stops, and the magnetic field dissipates. In contrast, permanent magnets have a built-in magnetic field that does not require an external power source, and superconducting magnets can maintain their magnetic field even without a continuous power supply due to the unique properties of superconducting materials. A bar magnet is a type of permanent magnet.Rate this question:
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- 31.
Which of the following is a disadvantage of resistive magnets?1. high energy consumption2. high cooling requirements3. not easy to shut off magnetic field
- A.
1 and 2
- B.
1 only
- C.
1 and 3
- D.
2 only
Correct Answer
A. 1 and 2Explanation
Resistive magnets have a disadvantage of high energy consumption because they require a constant supply of electricity to maintain the magnetic field. Additionally, they have high cooling requirements because the electrical current flowing through the resistive material generates heat, which needs to be dissipated to prevent damage to the magnet. Therefore, options 1 and 2 are both disadvantages of resistive magnets.Rate this question:
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- 32.
The material in the coil of wire which makes up a superconducting magnet exhibits no electrical resistance when it is
- A.
Cooled to extremely low temperatures
- B.
Attached to a battery
- C.
In an air conditioned room
- D.
Heated to extremely high temperatures
Correct Answer
A. Cooled to extremely low temperaturesExplanation
Superconducting magnets are made using a coil of wire that contains a material with superconducting properties. When this material is cooled to extremely low temperatures, usually close to absolute zero, it exhibits no electrical resistance. This means that electric current can flow through the wire without any loss of energy. This property is crucial for the functioning of superconducting magnets, as it allows them to generate strong magnetic fields without overheating or wasting energy. Therefore, the correct answer is "cooled to extremely low temperatures".Rate this question:
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- 33.
__ magnets require the use of cryogens
- A.
Bar
- B.
Resistive
- C.
Superconducting
- D.
Permanent
Correct Answer
C. SuperconductingExplanation
Superconducting magnets require the use of cryogens because they operate at extremely low temperatures. Cryogens, such as liquid helium, are used to cool down the superconducting material below its critical temperature, at which it exhibits zero electrical resistance. This allows the magnet to generate a strong and stable magnetic field without any energy loss. The use of cryogens is necessary to maintain the superconducting state and ensure the proper functioning of the magnet.Rate this question:
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- 34.
_ magnets are not availabe in clinical MR systems to produce a magnetic field of 3.0T1. resistive 2. permanent3. superconducting
- A.
3 only
- B.
1 and 2
- C.
2 only
- D.
1 only
Correct Answer
B. 1 and 2Explanation
Clinical MR systems use both resistive and permanent magnets to produce a magnetic field of 3.0T. Resistive magnets are made of coils of wire that generate a magnetic field when an electric current is passed through them. Permanent magnets, on the other hand, have a fixed magnetic field that does not require an electric current. Superconducting magnets, which rely on the property of superconductivity, are not used in clinical MR systems. Therefore, the correct answer is 1 and 2.Rate this question:
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- 35.
_ magnets use the most electrical power to create their magnetic field
- A.
Permanent
- B.
Resistive
- C.
Superconducting
- D.
Bar
Correct Answer
B. ResistiveExplanation
Resistive magnets use the most electrical power to create their magnetic field because they rely on the flow of current through a resistive material, such as a coil of wire, which generates heat and consumes energy. This resistance leads to a higher power requirement compared to permanent magnets, which do not require any power input, or superconducting magnets, which have zero resistance and can maintain a magnetic field without power once they are initially energized. Bar magnets are also permanent magnets and do not require electrical power to create a magnetic field.Rate this question:
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- 36.
_ magnets can be shut off most quickly in the case of an emergency
- A.
Permanent
- B.
Superconducting
- C.
Resistive
- D.
Bar
Correct Answer
C. ResistiveExplanation
Resistive magnets can be shut off most quickly in the case of an emergency because they rely on the resistance of the material to generate a magnetic field. By cutting off the power supply, the flow of current can be stopped almost instantly, resulting in the rapid deactivation of the magnet. In contrast, permanent magnets have a constant magnetic field and cannot be easily turned off, while superconducting magnets require a complex process to cool down and switch off. A bar magnet is not mentioned in the question and therefore not relevant to the explanation.Rate this question:
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- 37.
Which of the following is a disadvantage of resistive magnets?1. high energy consumption2. high cooling requirements3. not easy to shut off magnetic field
- A.
1 and 2
- B.
1 only
- C.
1 and 3
- D.
2 only
Correct Answer
A. 1 and 2Explanation
Resistive magnets have a disadvantage of high energy consumption because they require a continuous flow of electrical current to maintain their magnetic field. Additionally, they have high cooling requirements because the electrical current passing through them generates heat, which needs to be dissipated to prevent overheating. Therefore, options 1 and 2 correctly identify the disadvantages of resistive magnets.Rate this question:
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- 38.
Which of the following statements is true regarding the magnets used in MR systems1. some superconducting magnets can produce magnetic fields up to 10 T2. resistive magnets may only have horizontal magnetic fields3. permanent magnets are ideal for use in mobile MR systems
- A.
1 only
- B.
1 and 2
- C.
3 only
- D.
1 and 3
Correct Answer
A. 1 onlyExplanation
Superconducting magnets used in MR systems can produce magnetic fields up to 10 T, which makes statement 1 true. However, statement 2 is false as resistive magnets can have both horizontal and vertical magnetic fields. Statement 3 is also false as permanent magnets are not ideal for use in mobile MR systems. Therefore, the correct answer is 1 only.Rate this question:
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- 39.
MR guided _ is an application of interventional MRI1. biopsy2. surgery3. ablation therapy
- A.
2 and 3
- B.
1, 2, and 3
- C.
1 and 2
- D.
1 and 3
Correct Answer
B. 1, 2, and 3Explanation
MR guided surgery, biopsy, and ablation therapy are all applications of interventional MRI. Interventional MRI combines real-time imaging with minimally invasive procedures, allowing for precise targeting and monitoring of the treatment. MR guided surgery involves using MRI to guide surgical procedures, improving accuracy and reducing invasiveness. MR guided biopsy uses MRI to guide the placement of a needle or probe to obtain tissue samples for diagnosis. MR guided ablation therapy uses MRI to guide the delivery of thermal or non-thermal energy to destroy tumors or abnormal tissue. Therefore, options 1, 2, and 3 are all correct answers.Rate this question:
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- 40.
The fringe magnetic field:
- A.
Is eliminated by using magnetic shielding
- B.
Is eliminated by shimming
- C.
Poses no safety risk if magnetic shielding is used
- D.
Can cause other nearby medical devices to malfuntion
Correct Answer
D. Can cause other nearby medical devices to malfuntionExplanation
The fringe magnetic field generated by medical devices can cause nearby medical devices to malfunction. This is because the magnetic field can interfere with the functioning of these devices, leading to incorrect readings or improper operation. Magnetic shielding is used to eliminate the fringe magnetic field and prevent such malfunctions. By containing the magnetic field within the device, shielding ensures that it does not extend beyond its intended area of influence, thereby reducing the risk of interference with other medical devices.Rate this question:
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- 41.
The magnetic shielding
- A.
Reconstructs the images using the Fourier transform
- B.
Makes the magnetic field more uniform
- C.
Liearly varies the magnetic field along the axis of the magnet
- D.
Constrains the fringe magnetic field to a smaller space
Correct Answer
D. Constrains the fringe magnetic field to a smaller spaceExplanation
The correct answer is "constrains the fringe magnetic field to a smaller space." Magnetic shielding refers to the use of materials that can redirect or absorb magnetic fields. In the context of this question, the purpose of magnetic shielding is to limit the spread or influence of the fringe magnetic field to a smaller area. By doing so, it helps to minimize interference or unwanted effects caused by the fringe magnetic field.Rate this question:
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- 42.
The __ gradient coils are wrapped on the top and bottom of the gradient cylinder
- A.
Z
- B.
X
- C.
X and z
- D.
Y
Correct Answer
D. YExplanation
The correct answer is "y". In MRI machines, gradient coils are used to create a magnetic field that varies in strength across different regions of the body. This allows for spatial encoding of the signals received during imaging. The gradient coils are typically wrapped around the gradient cylinder, with coils on the top and bottom. Therefore, the coils are present in the y-direction.Rate this question:
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- 43.
The __ encodes frequencies and phases into the MR echoes
- A.
Gradient coils
- B.
Host computer
- C.
RF coils
- D.
Analog to digital convertor
Correct Answer
A. Gradient coilsExplanation
Gradient coils are responsible for encoding frequencies and phases into the MR echoes. These coils produce magnetic field gradients, which are used to spatially encode the MRI signal. By applying different gradients in different directions, the MRI scanner can distinguish between different tissues and create detailed images. The host computer, RF coils, and analog-to-digital converter are all important components of an MRI system, but they do not directly encode frequencies and phases into the MR echoes.Rate this question:
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- 44.
_is the definition of Faraday's law
- A.
A moving electron that will induce an electric field in a neighboring conductor
- B.
A moving electron that will induce a magnetic field in a neighboring conductor
- C.
A changing magnetic field that will induce an electrical current in a neighboring conductive material
- D.
A changing electric field that will induce a magnetic field in a neighboring conductor
Correct Answer
C. A changing magnetic field that will induce an electrical current in a neighboring conductive materialExplanation
Faraday's law states that a changing magnetic field will induce an electrical current in a neighboring conductive material. This means that when the magnetic field surrounding a conductor changes, it creates an electric current in the conductor. This phenomenon is the basis for many electrical devices and technologies, such as generators and transformers.Rate this question:
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- 45.
Which of the following is an example of Faradays law of induction?1. precessing net magnetization of protons inducing an electrical current in a surface coil2. precessing net magnetization of protons emitting an echo in response to RF pulses3. net magnetization of protons precessing at a rate governed by the strength of the magnetic field they are exposed to
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1 AND 2
Correct Answer
A. 1 onlyExplanation
Faraday's law of induction states that a changing magnetic field induces an electromotive force (EMF) in a conductor. In option 1, the precessing net magnetization of protons (changing magnetic field) induces an electrical current in a surface coil (conductor), which aligns with Faraday's law. Option 2 is not an example of Faraday's law as it describes the emission of an echo in response to RF pulses, which is not related to the induction of an EMF. Option 3 describes the precession of net magnetization, but it does not mention the induction of an EMF. Therefore, the correct answer is 1 only.Rate this question:
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- 46.
Which of the following is the function of the RF coils?1. transmission of the RF pulses2. digitizing the received MR echoes3. reception of the MR echoes
- A.
1 and 2
- B.
1 and 3
- C.
2 and 3
- D.
1, 2, and 3
Correct Answer
B. 1 and 3Explanation
The RF coils have two main functions: transmission of the RF pulses and reception of the MR echoes. The transmission of RF pulses is necessary for creating the magnetic field required for the imaging process. The RF coils then receive the MR echoes, which are the signals generated by the interaction between the magnetic field and the tissues in the body. Therefore, the correct answer is 1 and 3.Rate this question:
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- 47.
A _ coil is preferable when a very uniform signal intensity level must be achieved throughout a cross section of anatomy
- A.
Volumetric
- B.
Linear
- C.
Flat array
- D.
Surface
Correct Answer
A. VolumetricExplanation
A volumetric coil is preferable when a very uniform signal intensity level must be achieved throughout a cross section of anatomy because it is designed to provide consistent signal reception and transmit power over a larger volume of tissue. This type of coil is able to cover a larger area and capture signals from a wider range of angles, resulting in a more uniform signal intensity throughout the entire cross section of the anatomy being imaged.Rate this question:
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- 48.
Which of the following is true regarding function of RF coils1. The same coil may be used to transmit and receive the MR echoes2. seperate coils may be used to transmit the RF pulses and to receive the MR echoes3. a surface coil would be optimal for imaging structures deep within the brain
- A.
1 only
- B.
2 only
- C.
1 and 2
- D.
1 and 3
- E.
1, 2, and 3
Correct Answer
C. 1 and 2Explanation
Both statements 1 and 2 are true regarding the function of RF coils. Statement 1 states that the same coil may be used to transmit and receive the MR echoes, which is true as RF coils are used for both transmitting and receiving radiofrequency signals in MRI. Statement 2 states that separate coils may be used to transmit the RF pulses and to receive the MR echoes, which is also true as some MRI systems use separate coils for transmission and reception to optimize the performance of each function. Therefore, the correct answer is 1 and 2.Rate this question:
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- 49.
An RF coil geometry which links together several small surface coils in order to image a larger field of view is called _ coil
- A.
An array coil
- B.
A volumetric coil
- C.
A circularly polarized
- D.
A quadrature
Correct Answer
A. An array coilExplanation
An RF coil geometry that links together several small surface coils in order to image a larger field of view is called an array coil. This configuration allows for improved signal reception and coverage over a larger area. By combining the signals from multiple smaller coils, an array coil can provide higher resolution and sensitivity in the imaging process.Rate this question:
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- 50.
A quadrature RF coil:1. uses two sets of coils oriented perpendicular to each other2. requires more power than an otherwise identical linear coil when transmitting3. has a higher signal to noise ratio than an otherwise identical linear coil
- A.
1 and 2
- B.
1 and 3
- C.
2 and 3
- D.
1, 2, and 3
Correct Answer
B. 1 and 3Explanation
A quadrature RF coil uses two sets of coils oriented perpendicular to each other, which allows for the generation of a rotating magnetic field. This configuration helps in achieving a higher signal to noise ratio compared to an otherwise identical linear coil. However, there is no mention of power requirements in the given information, so it cannot be concluded that a quadrature RF coil requires more power than a linear coil. Therefore, the correct answer is 1 and 3.Rate this question:
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