超音波加温における骨と筋肉の境界面での発熱原因の研究

酒本 勝之, 根岸 聡, 戸田 康永, 藤井 麻美子, 金井 寛

doi:10.11239/jsmbe1963.35.44

Unwanted temperature rise at muscle-bone interface has been one of the major problems during ultrasound hyperthermia treatment. In this study, we examined the alteration of temperature distribution caused by the existence of this interface from both computer calculation and model experiment. It has been said that this heat generation at the surface has a close relationship with the beam's incident angle. Ultrasound penetrates inside of a bone in two different waveforms, longitudinal wave and transversal wave. And the transmission factor of these two waves differ in great deal with the alteration of the incident angle. We first calculated the transmission factor as a function of incident angle from equation which was derived from the interrelationship of particle velocity and stress inside of a bone. Then, we obtained the sound pressure, SAR distribution and the tempeature rise distribution. From both theoretical and experimental results, the incident angle dependency of the interface heat was confirmed. And it is found that the mechanism of the heat generation relies to the incident angle, too. When the incident angle is less than the critical angle of the longitudinal wave, the main cause of the temperature elevation is due to the absorption of the longitudinal wave in the bone. As the angle gets larger, the reflection wave becomes the general origin of this unwanted heat. When the incident angle is larger than the critical angle of longitudinal wave, transversal wave becomes the major factor of the heat generation. Incident angle larger than the critical angle of the transversal wave produce no temperature rise due to the absorption of the bone.

超音波加温における骨と筋肉の境界面での発熱原因の研究

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収録刊行物

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超音波加温における骨と筋肉の境界面での発熱原因の研究

書誌事項

この論文をさがす

説明

収録刊行物

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書き出し

問題の指摘

詳細情報詳細情報について