Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1998-09-30
2001-06-19
Jaworski, Francis J. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C128S916000, C600S117000
Reexamination Certificate
active
06248074
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ultrasonic diagnosis system for producing an ultrasonic image with high positional precision. In the ultrasonic diagnosis system, the periphery of a magnetic sensor in a distal part of an ultrasonic probe, which has an ultrasonic transducer for producing an ultrasonic tomographic image and the magnetic sensor for detecting a position, is made of a non-conductive material in order to reduce an eddy current developing in the periphery of the magnetic sensor and to thus improve the precision in detecting the position of the distal part.
2. Description of the Related Art
In recent years, ultrasonic diagnosis systems for irradiating ultrasonic waves to the inside of a living body, extracting information of an intracorporeal state from echoes, and thus diagnosing a lesion have prevailed widely. Above all, an ultrasonic diagnosis system including an ultrasonic probe for irradiating ultrasonic waves intra-corporeally suffers less decay of ultrasonic waves than a type of ultrasonic diagnosis system that irradiates ultrasonic waves extra-corporeally. High-frequency ultrasonic waves of a high resolution can therefore be employed.
Japanese Unexamined Patent Publication No. 6-261900, describes prior art for detecting the position of an ultrasonic transducer by moving the ultrasonic transducer spirally and utilizing a magnetic field, and constructing a three-dimensional image.
FIG. 1
shows the structure of a prior art distal part
102
of an ultrasonic endoscope
101
serving as an ultrasonic probe. The distal part
102
consists of a distal body
105
attached to the distal end of a casing
104
outlining an insertion unit
103
, and a housing
106
. An illumination window
107
and objective window
108
are juxtaposed on an inclined surface formed near the center of the distal body
105
. A passage hole
110
through which a flexible shaft
109
lies is bored in the distal body
105
. The housing
106
communicating with the passage hole
110
is mounted on the distal end of the distal body
105
.
A holder
112
having an ultrasonic transducer
111
is located at the distal end of the flexible shaft
109
. The ultrasonic transducer
111
is placed in the housing
106
. A sealing member
113
for sealing the housing
106
is attached to the proximal end of the holder
112
. The housing
106
is filled with an ultrasound propagation fluid (for example, water)
114
. A magnetic sensor
115
serving as a position sensor is located at the distal end of the housing
106
.
Due to the foregoing structure, the flexible shaft
109
is rotated by a rotation unit that is not shown. This results in radial scanning. Spiral scanning is achieved by advancing or withdrawing the insertion unit
103
, that is, advancing or withdrawing the ultrasonic transducer
111
. A magnetic field generator is installed extra-corporeally. A magnetic field is detected by the magnetic sensor
115
, and sent to a position detector that is an external apparatus. Based on position data computed by involving the position detector, a three-dimensional image is constructed using numerous two-dimensional images resulting from spiral scanning by means of an external apparatus. The image is then displayed on a monitor.
As for the foregoing position sensor-inclusive ultrasonic endoscope, all components thereof including the distal body are made of a conductive material such as a metal. In a magnetic field generated by the magnetic field generator, an eddy current develops on each conductor to consume magnetic energy. This leads to a phenomenon that a magnetic field reaching the magnetic sensor
115
is disordered. Consequently, position detection is not achieved correctly, and a measurement error occurs.
SUMMARY OF THE INVENTION
The present invention provides an ultrasonic diagnosis system for producing an ultrasonic image with high positional precision by reducing an eddy current that develops around a magnetic sensor and by improving precision in position detection.
According to a preferred embodiment, the ultrasonic diagnosis system comprises an ultrasonic endoscope to be inserted into an object of observation, an ultrasonic transducer included in a distal part of the ultrasonic endoscope for producing an ultrasonic tomographic image, and a magnetic sensor included in the distal part for detecting the position of the ultrasonic transducer. The periphery of the magnetic sensor in the distal part of the ultrasonic diagnosis system is made of a non-conductive material. Consequently, an eddy current developing in the periphery of the magnetic sensor is reduced, and precision in position detection is improved. This enables provision of an ultrasonic diagnosis system capable of producing an ultrasonic image with high positional precision.
REFERENCES:
patent: 4802487 (1989-02-01), Martin et al.
patent: 5199437 (1993-04-01), Langberg
patent: 5353354 (1994-10-01), Keller et al.
patent: 5398691 (1995-03-01), Martin et al.
patent: 5997473 (1999-12-01), Taniguchi et al.
patent: 62-68442 (1987-03-01), None
patent: 4332544 (1992-11-01), None
patent: 6030937 (1994-02-01), None
patent: 6261900 (1994-09-01), None
Kawashima Tomonao
Kishi Kenji
Odachi Ichiro
Ohno Masahiro
Jaworski Francis J.
Olympus Optical Co,. Ltd.
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