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53 Cards in this Set
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- Back
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family members and ancillary personnel accompanying the patient into the scan room a. need not be screened because they are not undergoing the exam b. can enter the scan room to check on the patient but cannot stay during scanning c. should be screened as well just as if they are undergoing the exam d. must wear a lead apron during the procedure |
c have to be screened as well |
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in preparation for the exam, patients should be encouraged to a. wear their own clothing so as to feel at home with the study b. wear a wrist watch so they are aware of the length of the exam c. keep their hearing aid in so as to hear the commands d. change into a hospital gown or a scrub suit provided by the imaging department without snaps |
d gown |
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According the "white papers" on MRI safety, persons are identified into levels, whereby level 2 personnel include a. persons with NO mri training b. persons with limited training c. persons with extensive training d. there are no level 2 personnel in the white papers |
c extensive training. the white paper on MRI safety states that there are levels of expertise associated with MRI safety wherby -non mr personnel have little or not training in mri safety -level 1 personnel have limted training -level 2 personnel have extensive training in MRI training |
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the accepted standard of care for the detection of intraocular ferrous foreing bodies is a. CT b. MRI c. plain film d. visual exam |
c plain film |
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if monitoring is to be achieved by electrical and/or mechanical devices, it is important that compatibility with the MR system be demonstrated by a. clearance by FDA b. prior testing c. manufacturer declaration d. all of the above |
d. all of the above |
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the following items are usually allowed to enter the scan room in high magnetic field systems a. surgical steel hemostats b. surgical steel scissors c. copper tools d. laryngoscopes |
c copper tools |
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When used for MRI, cables from RF coils and ECG leads should be a. braided and placed straight through the imager b. laid along the patient's right arm, along the bore c. formed into loops with the imager d. neatly coiled and ready for use |
a braided and placed through the imager |
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surface coil cables can potentially cause damage to the patient when a. they are not frayed and rest along the arm of the patient b. they are slightly touching the patient and are frayed c. they are looped and not touching the patient d. all of the above e. none of the above |
d none. even though cables may look to be in excellent condition, any cable loops within the imager can potentially receive induced voltage. therefore, cables that touch the patient are automatically looped, given that the human body is conductive and the patient completes the loop |
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a quench can be used to a. improve image quality in MRI b. rapidly remove superconductivity and the magnetic field c. maintain magnetic field homogeneity d. satisfy the thirst of the tech e. lubricate the magnet coils |
b rapidly remove superconductivity and the magnetic field
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during a quench, patients and operators should be evacuated from the room to avoid a. asphyxiation and frostbite b. subarachnoid hemorrhage c. ruptured tympanic membranes d. a and c e. a, b and c |
all of the above during a quench, asphyxiation can result from the loss of oxygen, frostbite from the low temperatures of cryogens, and ruptured tympanic membranes from the increased pressure in the scan room that occurs as the liquid cryogen (He) returns to gas |
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what is regulated by the FDA a. length of the bore b. diameter of the bore c. acoustic noise d. scan time |
c acoustic noise |
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the unit of measure of RF absorption is a. watts per pound b. volts per pound c. watts per Kg d. volts per Kg |
c watts per Kg |
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for optimum operation of MRI systems, the ambient temperature and relative humidity should remain between a. 30-50 degrees/30-50% b. 65-75 degrees/50-70% c. 70-90 degrees/70-100% d. no specific temperature or humidity range |
b. 65-75 degrees with 50-70% humidity lowish temp lowish humidity |
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the acceptable safe level for exposure to magnetic fringe fields with respect to patients with cardiac pacemakers has been reported to be a. between 5 gauss and 15 gauss b. between 5T and 15T c. between 15g and 30g d. below 5g |
d below 5g |
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magnetic field shielding can be achieved either actively or passively. passive shielding can be achieved by lining the MRI scan room with a. copper b. steel c. lead d. none of the above |
b steel |
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RF shielding can be achieved by lining the MRI room with a. copper b. steel c. lead d. none of the above |
a copper |
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it is acceptable for the general population to be exposed to a field strength of a. 2 T b. 4 T c. 8 T d. 5 gauss |
d. general population assumed to not be screened and therefore not to be exposed to any magnetic field |
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MR imagers are magnetic field shielded such that: a. any metallic object can enter the scan room b. the fringe field is confined to/within the bore c. the fringe field is confined to/within the scan room d. there is not fringe field |
c shielding is used to confine fringe fields |
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fringe fields are less of a concern for a. mid-field superconducting imagers b. low field resistive imagers c. high field superconductive images that are shielded d. low field vertical field permanent magnet systems |
d low field vertical field permanent magnet systems |
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In july of 2003, the FDA's Center for Devices and Radiological Health (CDRH) modified the limit of RF absorption (dose) to __________for the head a. 2W/Kg for 5 mins b. 3W/Kg for 10 mins c. 4 W/Kg for 15 mins d. 12 W/Kg for 5 mins |
c 4 W/Kg for 15 mins |
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The FDA limits the allowable RF absorption to a. .2 W/Kg averaged over the body b. .4 c. 2.0 d. 4.0 |
d 4.0 W/Kg averaged over the body |
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the term used to describe RF absorption is a. Sensitive acquisition rate (SAR) b. Specific absorption rate (SAR) c. Susceptibility attack region (SAR) d. none of the above |
b Specific Absorption Rate (SAR) |
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The predominant biologic effect of RF fields is a. induced voltages b. tissue heating c. hypothermia d. magnetic hemodynamic effect |
b tissue heating. RF effects include increase to the body temperature due to tissue heating. induced voltages come from gradients, magnet hemodynamic effects come from the static magnetic field. Hypothermia results from exposure to cryogen during a quench |
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RF antenna effects can cause a. better reception on your car radio b. RF interference artifacts c. thermal injury and flames d. b and c |
d RF interference artifacts and thermal injury and flames |
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the FDA limits the effect of RF absorption to an increase in core body temperature of a. .1 degree Celsius b. 1 degree Celsius c. 10 degree Celsius d. there is no limit |
b 1 degree celsius |
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the increase in body temperature as the result of RF absorption is a. barely detectable b. greatest on the outside, becoming less at the center c. greatest at the center, becoming less on the surface d. evenly distributed throughout the body |
b greatest on the outside becoming less at the center |
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RF energy used in MRI is classified as a. high energy, ionizing radiation b. high energy, nonionizing radiation c. low energy, nonionizing radiation d. low energy, ionizing radiation |
c low energy, nonionizing radiation |
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as the flip angle is doubled, RF deposition increases by a factor of a. one b. two c. three d. four |
d four times |
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RF heating is more of a concern in imaging sequences such as a. gradient echo b. echo planar c. spin echo d. fast spin echo |
d fast spin echo. because fast spin echo uses a train (determined by the echo train length) of RF pulses to fill several lines of Kspace per TR and acquire images faster, tissue heating increases with increased RF. as flip angle increases, RF power deposition increases. as flip angle doubles (from 90 degrees to 180 degrees) RF power increases by a factor of 4 (four) |
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areas of the body that are most sensitive to the head (from SAR) are a. brain and spinal cord b. vertebral bodies c. globes of the eyes and testicles d. pancreas and liver |
c globes of the eyes and testicles |
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for adult imaging in MRI, the FDA guidelines limit the field strength of clinical imagers to a. 1.5T and below b. 2T and below c. 4T d. 8T |
d 8.0T |
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a magnetic field strength of 1T is equal to a. 1000g b. 10000g c. 100000g d. 10g |
b 10,000g |
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all of the following are regulated by the FDA EXCEPT a. field strength of the main magnet for clinical imaging b. RF absorption (SAR) c. gradient strength d. acoustic noise |
c gradient strength |
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No biologic effects have been reported in humans as the result of exposure to: A. Static magnetic fields above 2 T B. Time varying magnetic fields C. RF fields D. Static fields below 2T |
D Static fields below 2T |
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The field strength at is center is measured in units of: A. Gauss B. Tesla C. Watts D. SAR |
B Tesla |
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Magnetic field strength outside the image is usually measured in units of: A. Gauss B. Tesla C. Watts D. SAR |
A. Gausd |
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The attractive force that an object will experience at a distance of 7 feet from isocenter is dependent on: A. The ferro magnetic properties of the object B. The mass of the object C. The field strength of the system D. All of the above |
D All of the above |
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As a conductive medium (e.g. blood) moves across a magnetic field, an effect known as the magnetic he modena mic effect occurs, resulting in: A. Increased blood pressure B. Increased temperature C. Elevated T wave D. No noticeable effect |
C Elevated T wave |
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It is __________for all patients to be provided with hearing protection in the former of________. A. Required/headphones or earplugs B. Recommended/headphones or earplugs C. Required/head coil D. Recommended/helmet |
B Recommended/headphones or earplugs |
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The gradient magnetic fields: A. Produce heat in the gradient coils during the scan B. Can produce noise to cause temporary hearing loss C. Change rapidly during the scanning process D. All of the above |
D All of the above |
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When a patient is placed within the bore, an effect can be noted on the ECG whereby there is an elevated T wave. This effect is known as all EXCEPT: A. Magnetohydrodynamic effect B. Magnet-hydodynamic effect C. Magnet-hydodynamic effect D. Magnetophosphenes |
D Faraday law of induction states that if a conductor moves through a magnetic field, a voltage is induced within the conductor...blood is the conductor |
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The effect whereby the patient experiences a visual impression of seeing stars in their eyez, is known as: A. Magnetohydrodynamic B. Magnet-hydrodynamic C. Magnet-hemodynamic D. Magnetosphenes |
D Faraday law of induction states that if a conductor moves through a magnetic field, a voltage is induced within the conductor. In this case as the gradient fields are switched on and off during image acquisition, a voltage is induced within the retinal phosphenes |
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The FDA limit on time varying magnetic fields is: A. 10G/cm B. 6T/so C. 1G/cm D. Until the patient experiences peripheral nerve stimulation |
D Until patient has peripheral nerve stimulation |
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Time varying magnetic field (TVMF) effects include all of the following EXCEPT a. heat and increased body temperature B. Acoustic damage and hearing loss C. Peripheral nerve stimulation and tingling D. Magnetosphenes |
A Heat and increased body temperatures |
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TVMF effects are of greater concern for which scan sequences: A. FSE B. EPI C. GE D. SE
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B Epi |
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The strength of the gradient magnetic fields is measured in A. Millitesla per meter kilogram of body weight B. Watts per kilogram of body weightC. Watts per timeD. Gauss per cmE. A and d C. Watts per time D. Gauss per cm E. A and d |
E Gradient strength is measured in field strength over distance (m/Tm or G/cm) whereby 10mT/m=1g/cm |
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time varying magnetic fields have been reported to have caused: a. mild cutaneous sensations and images of flashing lights in patients b. involuntary muscle contractions and cardiac arrhythmias in patients c. neither of the above d. a and b |
d mild cutaneous sensations and images of flashing lights and involuntary muscle contractions and cardiac arrhythmias in patients |
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the FDA limit for the static magnetic field for clinical imaging for patients over 1 month of age is a. 1.0 b. 1.5 c. 4.0 d. 8.0 |
c 4.0T |
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The FDA limit for the static magnetic field for clinical imaging (including any and all patients) is a. 1.0 b. 1.5 c. 4.0 d. 8.0 |
c 4.0, 8.0T for patients over 1 month of age |
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The imaging sequence that is of most concern for time varying magnetic field effects is a. spin echo b. gradient echo c. fast spin echo d. echo planar |
d echo planar. Echo planar imaging uses gradients with very rapid rise times because all of the K space is filled in one TR time by changing the amplitude of the gradients as many as 128, 256, 512 times per TR period |
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gradient rise time is a. the time it takes for a gradient to get to full amplitude b. the time it takes for the cake to rise c. the time it takes for one TR to occur d. the time it takes for one acquisition to be complete |
a the time it takes for a gradient to get to full amplitude |
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The duty cycle is a. the time it takes for the gradient to reach its full amplitude b. the time it takes for one TR to occur c. the time the gradients are on during a TR period d. how much the gradient changes the magnetic field over a specific time |
c the time the gradients are on during a TR period |
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to avoid auditory damage during MRI, all patients should be offered a. headphones b. earplugs c. antinoise devices d. a and b e. a, b and c |
e all of them |
