Study of temperature distribution in agar agar phantom heated by 8MHz RF

概要

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The experimental system to obtain two - dimensional temperature distribution in a phantom was developed. The changes of thermal distribution during and after heating and the dependence of distribu-tion upon the volumes of phantom were investigated. The phantoms were heated with an 8 MHz RF capacitive heating unit with a pair of electrodes of 15 cm in diameter.<BR>1. The temperature distribution tended to become rather uniform due to thermal diffusion with the increase of the heating time and the time after the end of heating. To approximate temperature distribution to SAR (specific absorption rate) distribution, the heating time and the interval between heating and thermometry must be short.<BR>2. The temperature distribution got inhomogeneous with the increase of volume of phantoms heated with similar size electrodes. The standard phantom is necessary to evaluate the equipments and methods of heating.<BR>3. The coefficient of variation of temperature in the phantom was used to express the inhomogeneity of temperature distribution. The values agreed with the visual estimation.<BR>4. For the display of temperature distribution, it is necessary to define the reference point for normalization according to heating methods and equipments. In our paper, the center of a phantom where only a littele effect of thermal diffusion was observed, was defined as the reference point.
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