Biological Considerations

There will be five questions on biological considerations in the advanced-level examination for MRI. These will be drawn from the following subject areas

Radio frequency

– FDA guidelines

– Specific absorption rate

– Potential biological effects

Static field strength

– FDA guidelines

– Tesla

– Potential biological effects

Gradient fields

– FDA guidelines

– Time varying magnetic fields

– Potential biological effects

Radio Frequency

(Check box for correct answer)

Q26 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

Q27 In the United States, the FDA limits the allowable amount of RF absorption to:

(a)	0.4W/kg
(b)	4 W/kg
(c)	2 W/kg
(d)	There is no FDA limit

Q28 The term used to describe RF absorption is:

(a)	Sensitive Acquisition Range (SAR)
(b)	Specific Absorption Rate (SAR)
(c)	Susceptibility Attack Region (SAR)
(d)	None of the above

Q29 The unit of measure of RF absorption is:

(a)	Watts per pound
(b)	Volts per pound
(c)	Watts per kilogram
(d)	Volts per kilogram

Q30 The predominant biological effect of RF fields is:

(a)	Induced voltages
(b)	Tissue heating
(c)	Hypothermia
(d)	Magnetic hemodynamic effect

Q31 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

Q32 The FDA limits the effect of RF absorption to an increase in core body temperature of:

(a)	0.1°C
(b)	1°C
(c)	10°F
(d)	There is no limit

Q33 As the result of RF absorption an increase in body temperature 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