Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-04-30
2002-12-03
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S417000, C600S424000, C600S414000, C600S426000, C606S130000
Reexamination Certificate
active
06490477
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an imaging modality, including an imaging system for forming an image of an object to be examined, and an image guided surgery system, including: a position measuring system for measuring positions within the object, and a data processor for deriving a transformation between positions in the image of the object and corresponding positions within the object. The invention also relates to a method of forming an image of an object to be examined by means of an imaging system wherein a position and/or orientation in the object to be examined is measured. The invention further relates to a method of determining the position of a slice in an imaging system which forms slice images of an examination zone.
2. Description of Related Art
Imaging systems of this kind, capable of forming a slice image of an examination zone for medical purposes, are, for example X-ray computer tomography apparatus, MR apparatus or ultrasound apparatus. Since recently systems of this kind are also used for image guided surgery in order to reproduce or track surgical instruments during an intervention in the body of a patient. The exact position of the surgical instruments can then be determined by means of a position measuring system which measures the position of markers, for example light-emitting diodes (LEDs), provided on the instruments.
An imaging modality of this kind is particularly suitable for use in conjunction with image guided surgery. The image guided surgery system is used to show a position and/or orientation of a surgical instrument in an operating zone within the body of the patient to a user, such as a surgeon, during a surgical intervention. For these applications the object to be examined is a patient to be examined. The patient is examined notably so as to enable a surgical operation to be carried out as well as possible. Such a surgical operation is, for example a (radiological) intervention during which a surgical instrument is introduced into the body of the patient. The surgical instrument introduced into the body of the patient can be used to examine or treat the patient. For the introduction of the surgical instrument use is made of images made before and/or during the operation or intervention, for example X-ray images, computer tomography images or magnetic resonance images. The image guided surgery system includes the position measuring system for measuring the position and/or orientation of the surgical instrument. The image guided surgery system also includes the data processor which is provided with a computer for deriving corresponding positions in a relevant image from the measured positions of the surgical instrument. During the operation the position measuring system measures the position and/or orientation of the surgical instrument relative to the patient and the computer calculates the position and/or orientation corresponding to the measured position and/or orientation of the surgical instrument in such a previously made image. Said previously made image is displayed on a monitor, the actual position and/or orientation of the surgical instrument also being shown therein. The surgeon can observe the image on the monitor so as to see the position of the surgical instrument in the operating zone without having a direct view thereof. For example, the surgeon can observe the image on the monitor so as to determine how to move the surgical instrument in the operating zone without high risk of unnecessary damaging of tissues and notably without risk of damaging vital parts.
An image guided surgery system of this kind is employed, for example in neurosurgery to show the surgeon the exact position of the surgical instrument in the brain during a brain operation.
The imaging modality includes an imaging system. In case the imaging modality is formed by a computer tomography device, the imaging system includes an X-ray source and a detector system. The X-ray source and the detector system are arranged in a number of orientations relative to a patient to be examined in order to acquire a plurality of density profiles. Such density profiles represent the X-ray absorption in the patient to be examined in the respective orientations of the X-ray source and the detector system. One or more images of cross-sections of the patient to be examined are derived from the density profiles. In case the imaging modality is formed by a magnetic resonance device, the imaging system includes receiving coils for receiving magnetic resonance signals. The magnetic resonance signals are generated by spin polarization of nuclei in the patient by means of magnetic fields, followed by excitation of the nuclei. The decay of the nucleus from the excited state is accompanied by the emission of RF magnetic resonance signals. The signal levels of said magnetic resonance signals represent densities of notably protons in the patient to be examined. One or more images of cross-sections of the patient to be examined are derived from the magnetic resonance signals.
An imaging modality used in conjunction with an image guided surgery system is known from European patent application EP 0 600 610.
The known imaging modality includes an ultrasonic position measuring system. Such a position measuring system measures the actual position and/or orientation of a surgical instrument, notably an indicator pen. Furthermore, the patient to be examined is provided with markers which are screwed into the skull of the patient. The imaging modality also reproduces the markers in the image of the patient as formed by the image pick-up system. The position measuring system measures the positions of the markers. The transformation which converts the positions in the co-ordinate system relative to the patient into corresponding positions in the co-ordinate system in the image is derived from the measured positions of the markers and the positions of the images of the markers in the image of the patient. This transformation enables the corresponding position and/or orientation in the image to be derived from the actually measured position and/or orientation of the surgical instrument. The position and/or orientation of the surgical instrument can be reproduced in a rendition of the image of the patient. For example, a rendition of this kind is the image on the monitor showing the image of the patient together with the current position and/or orientation of the surgical instrument.
It is a drawback of the known imaging modality that it is necessary to provide the patient with markers which are screwed into the skull. Providing the markers is a time-consuming operation which is also quite painful to the patient.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an imaging modality which is suitable for use in conjunction with image guided surgery and does not necessitate the use of separate markers in or on the patient.
This object is achieved by means of an imaging modality according to the invention which is characterized in that the position measuring system is also arranged to measure the position and/or orientation of the imaging system, and that the data processor is also arranged to derive the transformation from the measured position and/or orientation of the imaging system.
The location of the region being imaged by the imaging modality is directly linked to the actual position and/or orientation of the imaging system. Furthermore, the image formed by the imaging system is also determined by the adjustment of the imaging system. It has been found that it is possible to derive the transformation between positions in the imaged region and in the image from the position and/or orientation of the imaging system with different adjustments of the imaging system. It is then no longer necessary to use images of separate markers. The adjustment of the imaging system concerns, for example the projection direction and the magnification with which the image is formed. The imaged region contains the part of the object to be examined which
Proksa Roland
Van Der Brug Willem P.
Zylka Waldemar
Qaderi Runa Shah
Vodopia John
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