10) Siting and Environment

When the distance from the center of an MRI unit doubles, the strength of the magnetic field decreases by which approximated factor?

A) 2

B) 4

C) 8

D) 16

E) 32

C) 8

Since the fringe field decays approximately with the 3^rd power of distance (r ) from the magnet’s isocenter (e.g. it is inversely proportional to r³) the shield placed farther away from the magnet does not need to be as heavy as the shield located close to it.

Which of the following is the most common method of magnetic field shielding for MRI installations?

A) actively shielded magnets

B) passively shielded magnets

C) unshielded magnets with shielded magnet rooms

D) actively shielded magnets with shielded magnet rooms

E) none, no magnetic shielding is needed

A) actively shielded magnets

The leakage of RF radiation into the magnet room most frequently occurs at:

A) the seals of the room window

B) the seams of the room door

C) the RF penetration panel

D) the filters and waveguides of electrical, HVAC, and plumbing services

E) the seams of the RF shield panels

B) the seams of the room door

Which materials are used to shield the MRI unit from parasitic RF signals?

A) copper

B) ClearPb (acrylic impregnated with Pb)

C) gypsum board

D) lead

E) plywood

A) copper

All of the following factors play a critical role in designing an MRI facility EXCEPT

A) fringe magnetic fields of the magnet

B) parasitic RF signals entering the magnet room

C) mechanical vibrations in the building

D) spikes, brownouts, and other variations in the electrical power lines

E) LCD computer monitors in an adjacent room

The FDA mandates that patients with electronic implants be kept away from magnetic fields in excess of:

A) 1 gauss

B) 2 gauss

C) 5 gauss

D) 10 gauss

E) 50 gauss

C) 5 gauss

Fire suppression system in the magnet room:

A) requires special design to prevent artifacts in acquired MR images

B) must not be used because it will damage the magnet

C) requires hand held fire extinguishers

D) requires fire hydrant with hose installed outside magnet room door

E) can dump halon into the room in case of fire.

A) requires special design to prevent artifacts in acquired MR images

Which of the following is useful in reducing the fringe field from an MR magnet?

A) active shield coils

B) shim coils

C) lead shielding

D) copper shielding

E) concrete walls around the magnet room

A) active shield coils

The use of telephones in the MRI scanner room:

A) is strictly forbidden due to patient safety

B) is discouraged due to possible negative impact on image quality

C) is permitted if a wireless cell phone is used

D) is strongly advised for access to emergency networks

E) is required by federal safety regulations in case of emergency

A) is strictly forbidden due to patient safety

5.0 mT or less: MR RF power amplifier, main disconnect device (electrical equipment used to connect MR hardware to building power), telephones, metal detector devices

10.

Television sets inside the MRI scanner room:

A) cannot be used because they will compromise the RF shielding

B) are not used because the patient cannot see outside the magnet bore

C) are sometimes used at the patient’s request

D) are employed to distract claustrophobic patients

A) cannot be used because they will compromise the RF shielding

In some ways this is not a sporting question. Presumably they mean CRT TV? Then they will not funstion as noted.

0.1 mT or less: PET scanners, cyclotrons, linear accelerators, CRT color TV sets, video display (color), CRT monitors, CT scanners, ultrasound machines, lithotripters

Certainly there are commercial products that get video images to pts. in the scanner for claustrophobia, functional paradigms, etc.

11.

Transmission of audio signals into the magnet room:

A) is strictly forbidden due to negative impact of the signals on image quality

B) is possible but headphones and special equipment must be used to overcome the noise created by the MRI hardware

C) is possible as long as speakers are positioned at a distance from the magnet

D) is rare due to the high cost related to the special requirements in the MRI environment

B) is possible but headphones and special equipment must be used to overcome the noise created by the MRI hardware

12.

The boiling point of liquid helium (LHe) under normal atmospheric pressure is equal to:

A) 4.2 K

B) 15 K

C) 22 K

D) 77 K

E) 211 K

A) 4.2 K

13.

Large windows in the walls of the MRI magnet room:

A) must be made from dual-pane, tempered glass panes, to prevent foreign metallic object from being sucked in by the magnet;

B) must be made using the special E-coating on glass surfaces to provide adequate RF shielding;

C) must be semi-transparent to ensure patient privacy;

D) have to include additional RF mesh screens to ensure adequate RF shielding;

E) must be avoided because they don’t allow adequate climate control in the magnet room.

D) have to include additional RF mesh screens to ensure adequate RF shielding;

14.

Most mobile MRI scanners are transported among imaging sites in the following condition:

A) the magnet is kept energized (i.e. at field) but the electronics are turned off;

B) the magnet is ramped down (i.e. without a field), but left filled with cryogens;

C) the magnet is ramped down and the cryogens are removed to separate storage that’s safe for transportation;

D) the magnet is energized and the electronics are turned on with power provided by a generator located in the undercarriage of the trailer;

E) the magnet is deliberately quenched, all electronics is turned off, no electrical power is available.

A) the magnet is kept energized (i.e. at field) but the electronics are turned off;

Could not find reference in the module.

15.

Who is responsible for maintaining the adequacy of the RF shield around the MRI magnet during clinical operation?

A) the vendor of the RF shield;

B) the installer of the shield;

C) the vendor of MRI equipment;

D) the MRI service engineers;

E) the owner of the MRI facility.

16.

The loud noise, heard during MR scanning, is produced by:

A) the magnet's cryoventing system

B) the RF transmit coil and the gradient(MFG)coils

C) the magnet’s cold head

D) the eddy currents in the RF shield

E) the patient

B) the RF transmit coil and the gradient(MFG)coils

17.

Which components of an MRI scanner have the longest useful service lifespan?

A) the magnet

B) the RF electronics

C) the computers

D) the software

E) the RF shielding enclosure

18.

Installation of a water faucet and sink inside the magnet room:

A) is not possible, it will compromise the integrity of RF shield

B) requires use of sterilized water to prevent biological contamination of the room

C) requires use of demineralized water

D) requires use of deionized water

E) does not require any special measures

C) requires use of demineralized water

19.

Detachable patient table that can be undocked from the MRI scanner and wheeled out of the room:

A) is required for all MRI scanners due to patient safety regulations

B) is required only for MRI scanners used for inpatient procedures in hospital installations

C) is required for high-field (3T and above) MRI systems

D) is an optional feature available on some scanners

E) is not used in MRI facilities

D) is an optional feature available on some scanners

20.

Wireless RF (WiFi) technology used for patient monitoring:

A) can be used on patients undergoing MRI examinations without restrictions

B) is prohibited inside the magnet room

C) can be used inside the magnet room if specifically designed for MRI installations

D) is required for inpatient MRI procedures in hospital installations

E) is not used in MRI facilities

C) can be used inside the magnet room if specifically designed for MRI installations