[in Japanese]

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Japan is an oceanic and archipelagic state and all big cities are located near the sea shore line. So importance of hospital ship and disaster relief ship had been pointed in Japan. After the Great East Japan Earthquake in March 2011, usefulness and needs for hospital ship were strongly proposed again. There exist many application fields of computer aided surgery for medical and humanitarian support activities in the hospital ship. Outlines and problems of hospital ship are presented in this paper.

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Objective: To investigate the feasibility and accuracy of a newly-developed surgical marking system using gastrointestinal clip with radio-frequency identification (RFID) tag. Method: RFID is a technology for near field communication. The band, 13.56 MHz, is one of the open-bands for medical use and is suitable for the marking system in biological tissues because of its linear signal decay properties. The proposed system consists of four parts: (1) 13.56 MHz RFID reader and writer, (2) Gastrointestinal clip with RFID-tag, (3) Sensor antenna, (4) and Signal processing units with indicator. In the experiments using canine model, two or three clips were endoscopically applied in the esophagus of six dogs. During the subsequent operation, the clips were localized by the detection of RFID signal from the tag, and the detected sites were marked on adventitia by ablation. Longitudinal distance between the clips and the (metal) pin-needle which were pierced from ablated adventitia were measured with X-ray radiographs of the resected specimen. Result:All clips (14/14) were successfully detected and the detection time was 15.0 ± SD11.6 seconds. Longitudinal distance was 3.0 ± SD2.3 mm. Conclusions: Gastrointestinal clips with RFID-tag were localized by our system with substantial accuracy in the experimental setting using canine esophagus.

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High-intensity focused ultrasound (HIFU) relies on the absorption of ultrasound irradiation to non-invasively cause thermal ablation of a tumor. We developed the cavitation suppression technique (CAST) to minimize the risks of non-target tissue damage during HIFU. This study examined the accurate focusing of the ultrasound beam to achieve precise locational targeting. In excised livers, HIFU was used to ablate specific areas of tissue. Although the theoretical volume of the ablated tissue was 1000 mm3, the volume without CAST use was 2641 ± 671 mm3; using CAST, the volume was 1148 ± 356 mm3. The deviation of the focal points in the direction of the ultrasound transducer, without CAST, was 5.0 ± 1.7 mm, but was reduced to 1.2 ± 1.5 mm when CAST was used. The technique was used to ablate hepatic tumors in rabbits, resulting in the ablated area being clearly demarcated from the adjacent, normal liver tissue. The tumor was completely ablated and necrotized. Thus, the new technique CAST may enable more accurate clinical use as a next-generation HIFU therapy for liver tumors.

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