A prototype RF dosimeter for independent measurement of the average specific absorption rate (SAR) during MRI.
A prototype RF dosimeter for independent measurement of the average specific absorption rate (SAR) during MRI.
复制标题
原型射频剂量计，用于在 MRI 期间独立测量平均比吸收率 (SAR)。
DOI：
10.1002/jmri.21141
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Bottomley,PaulA
中科院分区：
文献类型：
--
作者：
Stralka,JohnP;Bottomley,PaulA
PurposeTo develop a scanner‐independent dosimeter for measuring the average radio frequency (RF) power deposition and specific absorption rates (SAR) for human MRI exposure.Materials and MethodsA prototype dosimeter has a transducer with orthogonal conducting loops surrounding a small signal‐generating MRI sample. The loops contain resistors whose values are adjusted to load the scanner's MRI coils equivalent to an average head or body during MRI. The scanner adjusts its power output to normal levels during setup, using the MRI sample. Following calibration, the total power and average SAR deposited in the transducer are measured from the root‐mean‐square (rms) power induced in the transducer during MRI.ResultsA 1.5 Tesla head transducer was adjusted to elicit the same load as the average of nine adult volunteers. Once adjusted, the transducer loads other head coils the same as the head does. The dosimeter is calibrated at up to 20 W total deposited power and 4.5 W/kg SAR in the average head, with about 5% accuracy.ConclusionThis dosimeter provides a simple portable means of measuring the power deposited in a body‐equivalent sample load, independent of the scanner. Further work will develop SAR dosimetry for the torso and for higher fields. J. Magn. Reson. Imaging 2007;26:1296–1302. © 2007 Wiley‐Liss, Inc.
