Recently, a, number of studies on the 3-D reconstruction of the ultrasound echography are described and published. 3-D Ultrasound echography, compared with other three dimensional medical images, e. g., MR(magnetic resonance)imaging, computed tomography(CT)and positron emission tomography(PET), is effective as an intraoperative use. However, the reconstruction requires computational power and that makes this study not applied to the sufficient clinical use. The authors developed a compact, mobile and less costly ultrasound computer reconstruction system for stereotactic neurosurgery. The system consists of sector probe(Aloka, 20mm in diameter)actuator for its rotation, ultrasound imaging system and personal computer for reconstruction. The probe is guided through a burr hole and automatically rotates in half circle and images gained among this movement are transferred to the personal computer. Then the computer reconstructs the four transverse images and displays on the extension monitor. With the us age of this system, the operator can obtain an ultrasound image on planes perpendicular to a trajectory; they are effective as an guidance for the surgical operation. Computational time scale is enough short(20 sec.)for the usage during the operation. The most attractive feature is that the cost is lower because the system needs only existing ultrasound imaging system and personal computer.

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Exact focusing in microscopic photography is sometimes difficult even at low magnification, because the depth of focus of the focus-detecting system including the human eye is longer than that of the photographing system. We have devised a focus-aid system to improve the focusing accuracy of microscope photography. The standard deviation of the focus position error with the present system is 1.1 μm in 100 trials, which is 1/9 of 9.5μm for manual focusing.

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The electrode-lead system for an ambulatory electrocardiographic system should be less sensitive to the noise interference than those of a standard ecg system because the patient under observation lives his normal daily life in his home and office where lots of inducing noise sources such as television sets and personal computers are in use.In an ambulatory ecg recorder the shielding effect of the conventional shield cables is not always sufficient to suppress the noise interference, because the lowest impedance of the electrodelead assembly is limited by the contact resistance between the electrode and the human skin. In this paper we report the immunity for noise interference of the electrode-lead system, in which a preamplifier is incorporated at the back of each electrode attached to the patient's body. With this configuration the level of the induced noise was reduced by 30db.

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