Surgery – Instruments – Stereotaxic device
Reexamination Certificate
2000-02-24
2002-04-09
Kamm, William E. (Department: 3762)
Surgery
Instruments
Stereotaxic device
Reexamination Certificate
active
06368331
ABSTRACT:
FIELD OF THE INVENTION
The present invention is generally in the field of the diagnosis and treatment of ailments such as cancer, and relates to a method and system for guiding a diagnostic or therapeutic instrument towards a target region inside the patient's body.
BACKGROUND OF THE INVENTION
Diagnostic and therapeutic techniques aimed at diagnosing and treating cancerous tumors are known and widely used. Some of them involve the insertion of an instrument such as a needle, from outside the patient into a tumor that is suspected of being cancerous. For example, a biopsy needle commonly is inserted into a tumor to withdraw a tissue sample for biopsy. In brachytherapy, a radioisotope is placed at the tip of a needle, and the tip of the needle is inserted into the tumor to deliver radiation to the tumor with minimal irradiation of the surrounding healthy tissue. Although not common in medical practice, chemotherapeutic agents also may be injected into the tumor using a needle. Such needles are often inserted into the patient utilizing a series of structural images of the patient, such as ultrasound images, images obtained with Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) techniques. These images are acquired before and during the insertion of the instrument, to verify that the instrument is being directed towards the correct target and is bypassing organs such as blood vessels, which should not be penetrated by the instrument.
Since a tumor may include both cancerous tissue and non-cancerous tissue, it is important to be able to direct an instrument specifically to a cancerous portion of a tumor, and to avoid misdiagnosis from the non-cancerous portion of a tumor. In the case of a biopsy, the needle should be directed towards the portion of the tumor that is most likely to be cancerous. In the case of brachytherapy, the needle should be directed towards the cancerous portion of the tumor. Structural imaging modalities, such as CT and MRI, that have enough spatial accuracy and resolution to distinguish and resolve tumors, are nevertheless unable to differentiate cancerous tissue from non-cancerous tissue. Functional imaging modalities, including tomographic nuclear imaging modalities, such as Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET), can distinguish cancerous tissue from non-cancerous tissue, but lack the spatial accuracy and resolution that is needed for the accurate positioning of instruments such as biopsy needles and brachytherapy needles.
Techniques for registering a functional image with a structural image to produce a combined image have been developed, and are disclosed, for example in the following publications: M. W. Vannier and D. E. Gayou, “Automated registration of multimodality images”,
Radiology
, vol. 169 pp. 860-861 (1988); J. A. Correia, “Registration of nuclear medicine images,
J. Nucl. Med.
, vol. 31 pp. 1227-1229 (1990); J-C Liehn, A. Loboguerrero, C. Perault and L. Demange, “superposition of computed tomography and single photon emission tomography immunoscinigraphic images in the pelvis: validation in patients with colorectal or ovarian carcinoma recurrence”,
Eur. J. Nucl. Med.
, vol. 19 pp. 186-194 (1992); F. Thomas et al., “Description of a prototype emission transmission computed tomography imaging system”,
J. Nucl. Med.
, vol. 33 pp. 1881-1887 (1992); D. A. Weber and M. Ivanovic, “Correlative image registration”,
Sem. Nucl. Med.
, vol. 24 pp. 311-323 (1994); and Hasegawa et al. U.S. Pat. No. 5,376,795. All six of these prior art documents are incorporated herein by reference for all purposes as if fully set forth herein. In principle, a sequence of such combined images could be used to direct an instrument to the cancerous portion of a tumor. In practice, the multiple imaging sessions and registrations that this would require make this solution impractical and possibly dangerous.
Stereotaxis is a known technique for localizing a region inside the body of a patient from outside the body of the patient, and for directing an instrument such as a needle, or a narrow beam of therapeutic radiation, to the target region. The degree of accuracy obtained from stereotaxis is relatively high, so this technique has been considered useful mainly on the brain and the breast. In stereotactic surgery of the brain, a CT localization frame is attached rigidly to the head of a patient and a CT image of the patient's brain is acquired with the CT localization frame in place. The position of the CT localization frame in the CT image is used to position the patient with respect to a surgical instrument utilizing a source of radiation so that the beam or beams of radiation intersects the desired target. Note that the CT localization frame is removed from the patient's head before the therapeutic irradiation commences.
Additionally, in order to access a correct location inside a patient's body with a diagnostic or therapeutic instrument, it is desirable to have exact information on the physical dimensions of the instrument. Using existing tools, such information can be obtained by one of the following means: prompting the user to enter all relevant physical dimensions; keeping a software library of known instruments and prompting the user for a specific model type; or prompting the user to perform a series of actions with a calibration device. Needless to say, these are cumbersome and time-consuming procedures, and require caregiver assistance.
SUMMARY OF THE INVENTION
There is accordingly a need in the art to facilitate the technique of accessing a correct target region inside the patient's body with a diagnostic or therapeutic instrument, aimed at diagnosis and therapy purposes, by providing a novel method and system for guiding the instrument towards the target region, which is not necessarily located in the head or breast.
It is a major feature of the present invention to provide such a method that utilizes a combined image of at least a portion of the patient's body including a target region, which image is obtained by registering a high-resolution structural image and a relatively low-resolution functional image of this portion of the patient's body.
It is a further feature of the present invention to provide such a system that utilizes a guiding device having an indicator associated with a diagnostic or therapeutic instrument for presenting data indicative of a position of the indicator relative to any other point in the chosen portion of the patient's body.
The main idea of the present invention consists of the utilization of a combined image, obtained by registering structural and functional images of at least a portion of the patient's body including a target region, for guiding an instrument (diagnostic or therapeutic) towards the target. The structural and functional images are obtained using, respectively, structural and functional modalities, namely suitable known techniques, and the combined image is obtained by using any known suitable technique, for example, those disclosed in the above publications.
As used herein, the term “target” refers to a structurally discrete portion in the patient's body, such as an organ or a tumor, that is suspected of containing diseas (e.g., cancerous tissue). This diseased tissue (target) is surrounded by healthy tissues (e.g., non-cancerous tissue).
As used herein, the term “instrument” refers to a diagnostic or treatment instrument that can access and, if desired, be inserted into the target from outside the patient for the purpose of either diagnosis or treatment of a disease. Typical examples of such instruments include biopsy needles and needles for brachytherapy and chemotherapy.
According to one broad aspect of the present invention, there is provided a method for guiding an instrument towards a correct target inside the patient's body, the method comprising the steps of:
(i) providing an image of at least a portion of the patient's body including said target, wherein said image presents a comb
Ben-David Gal
Front Yaron
Kamm William E.
V-Target Ltd.
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