1999 Fiscal Year Final Research Report Summary
Thermal Ablation and Free Radicals induction by Focused Ultrasound as tool for Cancer Therapy
Grant-in-Aid for Scientific Research (A)
|Allocation Type||Single-year Grants |
|Research Institution||Chiba University |
ASANO Takehide Chiba University, School of Medicine Professor -> 千葉大学, 医学部, 講師 (80143311)
TAKAYAMA Wataru Chiba University, University Hospital Assistant, 医学部・付属病院, 助手 (60292702)
KENMOCHI Takashi Chiba University, University Hospital Lecturer, 医学部・付属病院, 講師 (50215133)
NAKAGORI Toshio National Cancer Center, 外科, 医師
JINGU Kazuhiko Chiba University, University Hospital Fellow, 医学部・付属病院, 医員
MIYAUCHI Hideaki Chiba University, University Hospital Fellow, 医学部・付属病院, 医員
|Project Period (FY)
1996 – 1999
|Keywords||High Intensity Focused Ultrasound / Active Oxygen / Photo Sensitizer / Thermal Ablation / Liver Tumor / Minimally Invasive Therapy / Liver Surgery / Acoustic Surgery / 位相差駆動 / 位相差駆動 / 低侵襲治療 / 低侵襲治療 / 肝臓外科 / 肝臓外科 / 超音波外科 / 超音波外科|
Focused Ultrasound has the potential ability to ablate selective tissue targets without damaging the intervening tissues between the transducer and target areas.
We have studied this technique from the following two point of view.
1) Fundamental studies on cancer therapy utilizing active oxygen that arises in ultrasonic field.
The measurement by ESR proved the production of hydroxyl radical and singlet oxygen by the ultrasonic cavitation. The ultrasound field with the radical productivity activated pre-medicated photo sensitizer, and that it strengthens the tumoricidal effect in does dependent fashion. This tumoricidal effect was suppressed by the ascorbic acid, which has potential of radical scavenger. The tumor growth of the mouse experimental model was also suppressed by this combination. The combined use of photo sensitizer and focused ultrasound can be expected as a new minimally invasive therapy for the tumor which is not adequate photo-dynamic therapy since it located further depth than photo can reach.
2) Thermal ablation by High intensity Focused Ultrasound (HIFU) as a tool for cancer therapy
When the focusing ultrasonic energy is further strengthened focused area become thermal ablation. Continuous irradiation of focused ultrasound causes cavitation in the targeted region, creating microbubbles. It impairs the ultrasound to reach on the target area. We have developed an irradiation device with a new technique called the CAST, aimed at controlling the occurrence of microbubbles, which combined single frequency waves and frequency modulation. A devise with CAST can be more correctly conducted ablation with predetermined size and spatial location without damaging to surrounding tissues. It could also ablate the target area of rabbit and pig liver, precisely.
An attractive thermal ablation method, HIFU would become a main therapeutic modality for liver, pancreas, and breast cancers in 21 century.
Research Products (18 results)