1989 Fiscal Year Final Research Report Summary
DEVELOPMENT OF A PORTABLE EXTRACORPOREAL LITHOTRIPTER USING A NEW PIEZOCERAMICS
| Project/Area Number |
63870065
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
Urology
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
KUWAHARA Masaaki Sch. Med., Urology, Assoc.Prof., 医学部, 助教授 (50006780)
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| Co-Investigator(Kenkyū-buntansha) |
OKAZAKI Kiyoshi Toshiba Med.Engn.Lab.Supervisor, 主査
AIDA Satoshi Toshiba R&D Center, Researcher, 研究員
ISE Hideo Sch.Med.1st Surg., Lecturer, 医学部, 講師 (10150260)
YOSHIKAWA Kazuyuki Sch.Med., Urology, Assis.Prof., 医学部, 助手 (10133977)
TAKAYAMA Kazuyoshi Inst.Fluid.Sci, Prof., 流体科学研究所, 教授 (40006193)
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| Project Period (FY) |
1988 – 1989
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| Keywords | Shock wave / Pizoceramics / Lithotripter / Clinical use / Animal experiment / Stone treatment |
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| Research Abstract |
In order to develop an original extracorporeal lithotripter using piezoceramics following subjects have been systematically investigated. A newly developed prototype machine is at present under clinical trial and its preliminary results shows satisfactory for future practical use.
1) In vitro basical experiments: As a first step a large-piece piezoceramic element was developed as a shock wave generator. However, a peak pressure in the focus was too small (200 bar) to destruct the stone. Following several improvements, a 24-piece element was finally developed (peak pressure 1500 bar, focal area 2x19 mm). For stone targeting an ultrasonic diagnostic system was adopted. Under ultrasonic observation a hyperechoic region developed in the focal region. Origin of the hyperechoic region was investigated and results indicated that acoustic cavitaion bubbles was probably responsible for its generation. The relationship between the applied shock waves (peak pressure and exposure rate) and the stone destructibility was also investigated.
2) Animal experiment: The human renal calculi or a model calculi was implanted in a dog kidney and the stone was extracorporeally disintegrated. The stone was satisfactorily distracted with reliable safety. microscopic observation revealed that the renal tissue injury occurred in the focal region, when exposed to focused shock waves. The injury was mainly attributable to the arterial damage.
3) Clinical application of a prototype lithotripter: The stone was easily detected by the ultrasonic diagnostic system as usual manner. Preliminary result showed that a stone-free rate was 52%, and spontaneous passage was expected in 24%. Therefore, total effectiveness was 76% in 33 patients, As a complication 3 to 5 times of hematuria were always observed postoperatively, but no other major complications. The results indicated that the machine was applicable to the practical use with satisfactory destructiveness and safety.
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Research Products
(12 results)
