What are principle issues that produce safety concerns as determined by the standards
developed by the ASTM? - Answer -displacement
-artifacts from passive implants
-RF Induced heating near passive implants
-torque
-marking medical devices for safety
What are principle issues that produce safety concerns as determined by the standards
developed by the ASTM? - Answer -displacement
-artifacts from passive implants
-RF Induced heating near passive implants
-torque
-marking medical devices for safety
All testing is designed for - Answer cylindrical bore MR systems only
Scanning a patient in a vertical field system who has an implant or device is considered -
Answer off-label (device was not tested)
Elongated objects are preferentially magnetized along the ________ dimension -
Answer longest
Torque is - Answer an item's tendency to align along the direction (axis) of B0 as it is
magnetized
Maximum torque is at - Answer isocenter
, At isocenter, B0 is - Answer homogenous and at maximum
The torque force of an item will scale approximately with - Answer B02 (square of B0)
Therefore, torque at 1.5T will be 4 times greater at 3T
The acceptance criteria for ASTM testing for torque requires - Answer the torque force
exerted on an item by B0 should be less than the force of gravity
Regarding translation, ferromagnetic objects tend to be pulled to - Answer region where
the dB/dx is stronger
Translational force= - Answer B0(dB/dx)
Magnetically saturated: - Answer at given field strength, items are as magnetically
saturated as they will become
Translational force at isocenter - Answer zero
Maximum dB/dx is at - Answer edge of magnet bore
The acceptance criteria for ASTM testing for translational force requires - Answer
magnetically induced force is less than the object's weight (force due to gravity)
Deflection angle is measured by the ASTM using - Answer protractor placed at entrance
of the bore near the bore wall. If the deflection angle measures less than 45 degrees,
the magnetically induced force is less than the force of gravity
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