Importance

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Abstract

A device for guiding a surgical needle (N) carried by a mount (30) into a blood vessel comprises receiving and transmitting ultrasonic transducers (26, 28). The transducers are positioned so that there is a point of convergence between the axis of the ultrasonic beam produced by the transmitting transducer and the axis of the line of sight along which the receiving transducer receives reflected waves. The mount (30) can perform both rotational and translational movements and the path along which the needle (N) moves when pushed into the patient intersects said point of convergence. The transducers (26, 28) and the mount (30) are interconnected so that movements of the needle mount (30) result in the transducers (26, 28) moving towards or away from one another so as to shift the point of convergence so that it remains coincident with the path along which the needle moves. In a further form the position of the needle mount is determined optically or magnetically and an output signal produced. The output signal is used to excite a phased array of ultrasonic transducers the outputs of which are arranged to interfere constructively along a specific axis. This axis is shifted as the needle mount is moved thereby to maintain the desired point of intersection between the line of sight of the receiving transducer, the axis along which the needle moves during insertion, and the axis along which constructive interference is occurring.

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