DEVELOPMENT OF THERMOACOUSTIC FREEZING TECHNIQUE FOR LIVER CANSER

2002 Fiscal Year Final Research Report Summary

• Project/Area Number: 13680942
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Biomedical engineering/Biological material science
• Research Institution: EHIME UNIVERSITY
• Principal Investigator: TAKAHASHI Manabu EHIME UNIVERSITY, ENGINERING, ASSOCIATE PROFESSOR, 工学部, 助教授 (20274334)
• Co-Investigator(Kenkyū-buntansha): WATANABE Yuji EHIME UNIVERSITY, MEDICINE, Assistant Professors, 医学部, 講師 (20210958) ; OKABE Nagatoshi EHIME UNIVERSITY, ENGINERING, PROFESSOR, 工学部, 教授 (20281181) ; NOMURA Shinfuku EHIME UNIVERSITY, ENGINERING, ASSOCIATE PROFESSOR, 工学部, 助教授 (20263957) ; TSUTSUMI Mitsuyoshi EHIME UNIVERSITY, ENGINERING, Assistant Professors, 工学部, 講師 (70293925)
• Project Period (FY): 2001 – 2002
• Keywords: LIVER CANSER / LOCAL FREEZING / THERMO ACAUSTIC COOLING / NEEDLE FOR COOLING / EXCISION RESISTANCE / TEMPERATURE FOR EXCISION / PARTIAL FREEZING / COOLING VELOSITY

Research Abstract

To excise a cancer along a free-designed resection curve, the formulation of the cooling phenomenon was conducted through the experiments using a liver of a pig. The physical properties were estimated by the reverse-analysis using the finite element method based on the heat transfer characteristic data of a liver. In addition, the proposed equation can express the relation among arbitrary cooling time and distance and temperature.
Isolation of the liver was conducted using a scalpel attached to the end-effector of a three-axes vertical revolute robot. Excision force showed minimum at a liver freezing temperature of 1.5 to - 2.0℃ in the experiments ; therefore, it is preferable that the liver be excised in this temperature range. By changing cooling velocity, the excision force becomes reduced when the cooling velocity is small even if the temperature of the liver remains the same. The lower the temperature of the liver is, the larger the increment rate of excision force is with regard t o cooling velocity.
The cooling experiment by thermo acoustic freezing in a brass tube was investigated experimentally. This thermo acoustic apparatus is composed of a brass tube used as the acoustic resonant tube and "stuck" inserted to this tube. The brass tube has 2 mm thick, with a inner diameter of 26 mm and a length of 1500 mm, which is equal to about 1/4 wavelengths. The stuck was made by bundling 100 tubes insulating tubes with an inner diameter of 1mm. A standard audio speaker adopted as the acoustic driver. The cooling experiment was carried out under the normal temperature normal pressure. The air and the helium gas were used as the working fluid. The temperature difference at both ends of the stack in the helium gas was three times larger than that in the air. The stack surface area, the internal local pressure, and the pressure amplitude of the speaker have a dominant role on the cooling capacity. It is possible to freeze the hepatocyte of about 1mm3 by using the present conventional (or simple) refrigeration system.