Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2001-04-27
2003-06-03
Smith, Ruth S. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S427000
Reexamination Certificate
active
06574498
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to remote manipulation of a probe such as a catheter and, more particularly, to a method for determining the position and orientation, with respect to a coordinate system external to an opaque body, of a probe within the opaque body. Typically, the opaque body is a patient undergoing a medical procedure and the probe is a catheter.
It is known to navigate a catheter through body cavities of a patient by electromagnetic means. See, for example, U.S. Pat. No. 5,558,091, to Acker et al., PCT Application WO 96/05768, to Ben-Haim et al., and PCT Application IL99/00371. In particular, PCT Application IL99/00371, which is incorporated by reference for all purposes as if fully set forth herein, teaches devices and methods for navigating a catheter through body cavities of a patient while simultaneously obtaining, in real time, images of the portion of the patient through which the catheter is inserted, and superposing on the images a representation of the catheter in true position and orientation.
FIG. 1
illustrates a C-mount fluoroscope
80
modified according to the teachings of IL99/00371 for simultaneous real-time image acquisition and intrabody navigation. Fluoroscope
80
includes the conventional components of a C-mount fluoroscope: an x-ray source
82
and an image acquisition module
84
mounted on opposite ends of a C-mount
78
, and a table
86
whereon the patient lies. Image acquisition module
84
converts x-rays that transit the patient on table
86
into electronic signals representative of a 2D image of the patient. C-mount
78
is pivotable about an axis
76
to allow the imaging of the patient from several angles, thereby allowing the reconstruction of a 3D image of the patient from successive 2D images. In addition, either a three-component electromagnetic field receiver
114
or a three-component electromagnetic field transmitter
24
is rigidly mounted on C-mount
78
. Receiver
114
or transmitter
24
serves to define a coordinate system that is fixed relative to C-mount
78
. Transmitter
24
, and another three-component electromagnetic field transmitter
24
′ that is not rigidly mounted on C-mount
78
, are driven by driving circuitry
32
. The electromagnetic waves generated by transmitter
24
or by transmitter
24
′ are received by receiver
114
and by another receiver
14
inside a probe
10
. The signals from receiver
14
that correspond to the electromagnetic waves generated by transmitter
24
or by transmitter
24
′ are sent to reception circuitry
34
. The signals from receiver
114
that correspond to the electromagnetic waves generated by transmitter
24
or by transmitter
24
′ are sent to reception circuitry
134
. Reception circuitries
34
and
134
and driving circuitry
32
are controlled by a controller/processor
36
that directs the generation of transmitted signals by driving circuitry
32
and the reception of received signals by reception circuitries
34
and
134
In addition, controller processor
36
implements the algorithm of PCT IL99/00371 to infer the position and orientation of probe
10
relative to transmitter
24
or to infer the positions of probe
10
and receiver
114
relative to transmitter
24
′. Controller/processor
36
also directs the acquisition of an image of the patient by image acquisition module
84
of fluoroscope
80
.
By determining the position and orientation of probe
10
relative to the coordinate system defined by transmitter
24
, controller/processor
36
determines the position and orientation of probe
10
relative to each acquired 2D image. Alternatively, the electromagnetic signals are transmitted by transmitter
24
′, and controller/processor
36
determines the position and orientation of probe
10
relative to the 2D images by determining the positions and orientations of receivers
14
and
114
relative to transmitter
24
′. Controller/processor
36
synthesizes a combined image that includes both the 3D image of the patient acquired by fluoroscope
80
and an icon representing probe
10
positioned and oriented with respect to the 3D image of the patient in the same way as probe
10
is positioned and oriented with respect to the interior of the patient. Controller/processor
36
then displays this combined image on a monitor
92
.
As noted in PCT IL99/00371, the methods taught therein for intrabody navigation are suitable for use in conjunction with a wide variety of devices for acquiring 2D or 3D images of the interior of the patient, in modalities including CT, MRI and ultrasound in addition to fluoroscopy.
Another family of systems, for determining the location of a probe such as a catheter within the body of a patient, uses a plurality of transducers on the surface of the patient's body and at least one similar transducer in the tip of the probe. The surface transducers define a reference system of coordinates. The signals produced by the various transducers are distinguishable from one another, and the character of the signals is diagnostic of the position on or within the patient's body at which the signals are received. Typically, either signals from the surface transducers are received by the probe transducers, or, exploiting the principal of reciprocity, signals from the probe transducers are received by the surface transducers. From these signals, the position of the tip of the probe relative to the reference coordinate system is determined. It should be noted that in this family of systems, the reference coordinate system, with respect to which the position of the probe is determined, is defined only with reference to the patient's body itself. This family of systems is incapable of determining the location of the probe with respect to a coordinate system external to, or independent of, the patient's body.
One example of such a system is taught by Smith et al. in U.S. Pat. No. 5,515,853, which is incorporated by reference for all purposes as if fully set forth herein. Ultrasonic signals are broadcast by a transducer (a piezoelectric crystal) at the tip of a catheter. These signals are received by a plurality of similar transducers on the patient's body, to measure the acoustic travel time from the tip of the catheter to the surface transceivers. The location of the tip of the catheter within the patient's body is determined by triangulation.
Another example of such a system is taught by Wittkampf in U.S. Pat. No. 5,697,377, incorporated by reference for all purposes as if fully set forth herein. Three substantially orthogonal alternating electrical currents, each of a different frequency, are applied through the patient's body via six electrodes mounted on the surface of the patient's body. A measuring electrode at the tip of a catheter measures the local electrical potential at each of the three frequencies. The displacement of the measuring electrode relative to lines connecting the pairs of surface electrodes is assumed to be linear in the three measured potentials. The surface electrodes define a (not necessarily orthogonal) reference coordinate system, and the three measured potentials are proportional to the coordinates of the measuring electrode in this coordinate system.
One drawback of the teachings of IL99/00371 is the relatively high cost and complexity of electromagnetic receivers
14
and
114
relative to the ultrasonic transceivers of Smith et al. and to the electrical transceivers of Wittkampf. It would be highly advantageous to have a method of intrabody navigation that relies on an electromagnetic technique to determine the position and orientation of the patient relative to the imaging device, while using some other technique, such as the ultrasonic technique of Smith et al. or the electrical technique of Wittkampf to determine the position and orientation of the probe relative to the patient's body.
DEFINITIONS
The term “transducer” usually is used to refer to a device that can interact with a physical
Friedman Mark M.
Smith Ruth S.
Super Dimension Ltd.
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