Meeting Banner
Abstract #2823

A Whole-Body RF Dosimeter for Independent SAR Measurement in MR Scanners

Di Qian1, 2, AbdEl-Monem M. El-Sharkawy3, Paul A. Bottomley, 23, William A. Edelstein1

1Radiology, Johns Hopkins School of Medicine, Baltimore, MD, United States; 2Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, United States; 3Radiology, Johns Hopkins University, Baltimore, MD, United States

We have developed an RF dosimeter for independent measurement of average whole-body RF exposure at 3T. The dosimeter includes an RF transducer with two tuned, orthogonal resistive loops and a lossless phantom. The loop impedances are adjusted so that the power deposited in the transducer is equivalent to that for an average human subject while minimizing B1-interference with the scanner. The deposited RF power is measured by sampling the current in the transducer loops. The dosimeter is tested on multiple GE, Philips, and Siemens MR systems, and can be used independent of make or model for a given MR frequency.

Abstract PDF

Keywords

achieve adjusted algebraic analytically analyzed applied assembled assessing attenuators audience ball body calculation calibration capacitors causing changing channel coil comprises computer connected consistent contour contribution copper correct correlated couplers curve curves deposited deposition derived desired determination determine determined developed devices directional distributed disturbance divided dosimeter dosimetry dynamic eight electrical engineering engineers ensuring equal equivalent essential established field final findings fixed forward frame frequency function give highly human important incorrectly independent induced initial inputs involve johns keeps leads length linear loading loop loops lossless lossy magnitude maintain make measure measured medical medicine mimics mineral minimal minimize model models monitor needed normalized operating optimization original orthogonal otherwise output particular phantom phys physicists plot polycarbonate positioned power powers prescribed previously produce produces property protection radiology rectangular reflected required researchers resistance resistor resistors resultant retuning safety scanner scanners school series service solution strip subject subjects systems target transducer transducers tuned tuning varied various whole width