Mri Equipment

1. A measure of the uniformity of the magnetic field of the system is a defintion of

Cryogen

Homogeneity

Quadrature

Precession

2. The link between the technologist and the computerized electronic environment of the MR system hardware

Equipment room

Equipment cabinet

Operator's console

Gradient amplifiers

3. Which of the following is the defintion of shimming

Adjusting homogeneity of the magnetic field

Creating a linear change in the magnetic field

Confining the magnetic field to a smaller arfea

Rapidly shutting off the magnetic field

4. Which of the following is a disadvantage of resistive magnets?
1. high energy consumption
2. high cooling requirements
3. not easy to shut off magnetic field

1 and 2

1 only

1 and 3

2 only

5. Which of the following is not a function of a PACS system

Image display for the radiologists

Digital distribution of images

Long term data storage

Reconstruction of the image from the raw data

6. The __ is located within an equipment cabinet

Magnetic shielding

RF power amplifier

Gradient coils

Rf coils

7. The _ provides the electrical power to the gradient coils

Pulse sequence controller

Rf power amplifier

Gradient power amplifier

Host computer

8. Which of the following describes an electromagnet

Magnetic bricks are stacked together to form the magnet

Electrical current flows through a coil of wire and generates a magnetic field

A changing magnetic field around a coil of wire generates an electic field

A moving magnetic field induces an electrical current in a neighboring conductive material

9. The magnetic shielding

Reconstructs the images using the Fourier transform

Makes the magnetic field more uniform

Liearly varies the magnetic field along the axis of the magnet

Constrains the fringe magnetic field to a smaller space

10. The host computer

Is the interface between the technologist and the MR system

Constrains the fringe magnetic field to a smaller space

Digitizes the MR echoes

Reconstructs the MR images

11. The array processor

Constrain sthe magnetic field within a smaller space

Lineraly varies the magnetic field along an axis of the magnet

Makes the magnetic field more uniform

Reconstructs the images using the Fourier transform

12. The fourier transform is performed by which MRI system component

Receiver amplifier

DAC

Array processor

Host computer

13. The _ provides the elctrical power to the gradient coils

Pulse sequence controller

Rf power amplifier

Gradient power amplifier

Host computer

14. A component used to increasze the strength of a signal

Gradient coil

Equipment cabinet

Digital to analog converter

Amplifier

15. _ magnets can be shut off most quickly in the case of an emergency

Permanent

Superconducting

Resistive

Bar

16. __ magnets must remain connected to a power source to maintain their magnetc field.

Resistive

Permanent

Superconducting

Bar

17. The operators may be used for:
1. converting digital to analog
2. viewing images
3. archiving images

1 and 2

1 and 3

2 and 3

1, 2, and 3

18. The RF shielding:
1. prevents the RF energy generated by the MR system from disturbing external radio signals
2. restricts external radio signals from being detected
3. prevents RF related artifacts from resulting

1and 3

1 and 2

1, 2, and 3

2 and 3

19. An RF coil geometry which links together several small surface coils in order to image a larger field of view is called _ coil

An array coil

A volumetric coil

A circularly polarized

A quadrature

20. The _ is responsible for telling the gradients when and at what strength to turn on

Magnetic shielding

Pulse sequence controller

Rf power amplifier

Host computer

21. __ magnets must be taken apart in order to shut off the magnetic field

Permanent

Superconducting

Electro

Resistive

22. Which of the following is true regarding function of RF coils
1. The same coil may be used to transmit and receive the MR echoes
2. seperate coils may be used to transmit the RF pulses and to receive the MR echoes
3. a surface coil would be optimal for imaging structures deep within the brain

1 only

2 only

1 and 2

1 and 3

1, 2, and 3

23. Which of the following is the function of the RF coils?
1. transmission of the RF pulses
2. digitizing the received MR echoes
3. reception of the MR echoes

1 and 2

1 and 3

2 and 3

1, 2, and 3

24. MR guided _ is an application of interventional MRI
1. biopsy
2. surgery
3. ablation therapy

2 and 3

1, 2, and 3

1 and 2

1 and 3

25. 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

Thickness of the slice

Field of view of the slice

Image orientation

Image matrix

26. The fringe magnetic field:

Is eliminated by using magnetic shielding

Is eliminated by shimming

Poses no safety risk if magnetic shielding is used

Can cause other nearby medical devices to malfuntion

27. Which of the following is a disadvantage of resistive magnets?
1. high energy consumption
2. high cooling requirements
3. not easy to shut off magnetic field

1 and 2

1 only

1 and 3

2 only

28. 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.

Tranverse

Oblique

Coronal

Sagittal

29. The pulse sequence controller is located

Inside the magnet

In the operator's console

On an rf coil

In the equipment cabinet

30. The echoes received from the patientgo through an amplifier to:

Close the RF recevier coil

In the operator's console

Close to the gradient power cabinet

In the pulse sequence controller

31. The __ gradient coils are wrapped on the top and bottom of the gradient cylinder

Z

X

X and z

Y

32. The __ encodes frequencies and phases into the MR echoes

Gradient coils

Host computer

RF coils

Analog to digital convertor

33. A quadrature coil is also known as a

An array coil

A circular polarized coil

A surface coil

A cardiac array coil

34. Which of the following statements is true regarding the magnets used in MR systems
1. some superconducting magnets can produce magnetic fields up to 10 T
2. resistive magnets may only have horizontal magnetic fields
3. permanent magnets are ideal for use in mobile MR systems

1 only

1 and 2

3 only

1 and 3

35. _is the definition of Faraday's law

A moving electron that will induce an electric field in a neighboring conductor

A moving electron that will induce a magnetic field in a neighboring conductor

A changing magnetic field that will induce an electrical current in a neighboring conductive material

A changing electric field that will induce a magnetic field in a neighboring conductor

36. A _ coil is preferable when a very uniform signal intensity level must be achieved throughout a cross section of anatomy

Volumetric

Linear

Flat array

Surface

37. A quadrature RF coil:
1. uses two sets of coils oriented perpendicular to each other
2. requires more power than an otherwise identical linear coil when transmitting
3. has a higher signal to noise ratio than an otherwise identical linear coil

1 and 2

1 and 3

2 and 3

1, 2, and 3

38. 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 coil
2. precessing net magnetization of protons emitting an echo in response to RF pulses
3. net magnetization of protons precessing at a rate governed by the strength of the magnetic field they are exposed to

1 only

2 only

3 only

1 AND 2

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MRI Equipment