MRSO - Static Field - Module 2 Text Review |Question and Answers| 100% Correct

MRSO - Static Field - Module 2 Text Review |Question and Answers| 100% Correct Static field metrics *Ans* 1T = 10,000G (0.5mT = 5G) Who published guidelines titled "Criteria for Significant Risk" that specifies what qualifies as significant risk of exposure to magnetic field associated with MRI. *Ans* FDA FDA guidelines state EXPOSURE to a static field that does not pose a significant risk is: *Ans* Limited to 8T for adults and infants 1 month Limited to 4T for infants 1 month Forces related to static field *Ans* -Torque/rotation -Translation/Displacement -Lenz magnetic saturation *Ans* The point where an increase in magnetic force produces no further magnetic effect in a magnetic material. . magnetic saturation depends on: *Ans* -material -size and shape -temperature Most ferromagnetic items are going to saturate at: *Ans* 0.3T - 2.2T Torque *Ans* force exerted on elongated ferromagnetic object so it aligns with the direction of the magnetic field Torque will cause an item to align in the _____________ axis in a horizontal field magnet. *Ans* z Torque will cause an item to align in the _____________ axis in a vertical field magnet. *Ans* y Torque is dependent on: *Ans* -length (longer=greater) -shape (elongatedsperical) -texture (soft/flexiblehard)(leads/wiresplate) -location in magnet (greatest at isocenter) Torque is greatest at *Ans* isocenter Translational / Displacement (missile effect) *Ans* attractive force on a ferromagnetic object in a spatial gradient magnetic field Translational force increases when *Ans* the field change over distance increases (dB/dx) Spatial gradient magnetic fields are expressed in *Ans* T/m or G/cm (1 T/m = 100 G/cm) Displacement force = *Ans* B0(dB/dx) Maximum translational force is at *Ans* point of maximum dB/dx At isocenter, translation force is *Ans* zero Highest spatial gradient for a VERTICAL field system is at *Ans* pole faces (item is more likely to attach to sides of poles rather than being drawn toward isocenter) Where do you obtain a spatial gradient map? *Ans* System vendor Highest spatial gradient for a HORIZONTAL field system is at *Ans* entrance to the bore near the magnet walls Magnetic shielding is used to *Ans* reshape/confine the field and bring 5G line int