| Project/Area Number |
07557104
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Urology
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| Research Institution | Tohoku University |
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Principal Investigator |
IORITANI Naomasa Tohoku Univ.Hospital, Reserach Associate, 医学部・附属病院, 助手 (50232145)
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| Co-Investigator(Kenkyū-buntansha) |
AIDA Satoshi Toshiba medical equipment and system research center, chief researcher, システム技術研究所, 主査(研究職)
HOSHI Senji Tohoku Univ.Urology, Associate Professor, 医学部, 助教授 (80107200)
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥21,100,000 (Direct Cost: ¥21,100,000)
Fiscal Year 1997: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1996: ¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 1995: ¥11,900,000 (Direct Cost: ¥11,900,000)
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| Keywords | HIFU / Cancer treatment / phase difference driving / cavitation suppression / frequency modification / CAST / 空洞形成 / Cavitation Suppression Technique / 加熱 / 癌治療 / キャビテーション抑制 / 超音波 / 癌 / 治療 / 高温 |
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| Research Abstract |
In order to establish the cancer therapy system, effect of the high intensity focused ultrasound heating was studied on the normal tissue and the experimental cancer tissue. The ultrasound source was a spherical piezo-ceramic peace that was applied to the tissue through water cushion. At first step, we used the conventional single frequency wave (SFW) driving, whose single burst for one second at 400 watts was effective enough to raise the temperature of focus area up to 100 degrees centigrade. The focused area showed an oval-shaped coagulation necrosis. The tissue structure of the focus was relatively preserved. However, this area was surrounded by a thin (0.5 - 1mm) annular zone with massive deformity of tissue structure. This zone was sharply demarcated by the normal surrounding area. However, when the bursts were given in a series to heat a certain volume, the focus temperature of later bursts could not achieve that of the first burst. The coagulation area also shifted to the sound source. These phenomena were due to cavitation of the ultrasound pass. we then interposed the frequency modulated wave between SFWs. This modification (Cavitation Suppression Technique : CAST) was so effective that posterior wall of rabbit bladder was effectively coagulated in contrast to subtle change by SFW.We also tried the focus size modification by using phase difference driving, in which the piezoceramic elements were divided into twelve pieces. The focus size increased to 10 mm with this device. This enlarged and attenuated focus was also effective to prevent the bumping in tissue which was frequently observed in liver with SFW without and with CAST.Using these devices, some tumors of mice and rabbits were effectively treated, however, tumor recurrence on peripheral area of tumors and in blood vessels were frequently observed. We are also working on the combination of chemotherapeutic agents and tumor immunology.
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