Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2001-09-12
2004-08-03
Sykes, Angela D. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S407000, C600S417000, C600S424000
Reexamination Certificate
active
06772002
ABSTRACT:
The present invention relates to a method and a device for navigation, in particular in intra-operative data capture. In general, the invention relates to a method and a device for localising a specified object, located for example in an external body such as for example a tumour, in a defined system of co-ordinates, such that it is possible to detect the spatial location of the tumour or of another area of interest exactly, continually and dynamically at any time, for example when a person in whom a tumour has been localised moves.
A method and a device for calibrating a navigation system with respect to image data from a magnetic resonance device for positioning a patient in a magnetic resonance device is known from DE 198 05 112 A1. In this respect, positions of at least three markers arranged in an image volume of a magnetic resonance device are determined in a first system of co-ordinates using a navigation system and in a second system of co-ordinates by means of magnetic resonance, whereby the position and orientation of the two co-ordinate systems relative to one another are determined from the positions of the markers in the two systems of co-ordinates, such that co-ordinate data from the first system of co-ordinates can be transformed into co-ordinate data of the second system of co-ordinates on the basis of a co-ordinate transformation matrix determined in this way. This method enables a patient to be positioned as exactly as possible in a magnetic resonance device, such that a specified area of the patient in which, for example, a tumour is suspected can be marked with an indicator instrument in order to produce a cross-sectional image in a plane given by the indicator instrument. If the patient is taken out of the magnetic resonance device again after imaging, then only the data of specified cross-sectional images are known, however an object of interest cannot be localised spatially, i.e. after the person has been taken out of the magnetic resonance device, the exact current spatial position of objects of interest in a person cannot be directly or precisely determined.
A method for comparing images recorded over a specified period of time with one another by means of nuclear spin resonance is known from the article “Motion Compensation by Gradient Adjustment” by H. Eviatar et al., Institute for Biodiagnostics, National Research Council Canada, Winnipeg, Manitoba, Canada; ISMRM Procedures 1997. To this end, reference elements are firmly attached to a head, said elements determining a recording area, such that it can be determined, in relation to these reference elements and independent of possible other positioning of a head to be examined relative to a magnet, whether certain areas of for example the brain have shifted due to relative movements. According to this method as well, it is not possible to continuously directly determine the position of an area of interest if a person to be examined has been taken out of the nuclear spin resonance device again.
It is the object of the present invention to propose a method and a device for determining the position of an object, such as for example a tumour in the cerebral tissue, which enable the relative position of the object of interest to be continually and precisely determined in a reference system of co-ordinates. In particular, a method and a device are to be proposed with which intra-operative images of a body containing the object can be taken, wherein the exact position of the object or of areas of interest or areas recorded with respect to a system of co-ordinates can be continually determined even if the body, for example a person to be examined, is taken out of, for example, a nuclear spin resonance or computer tomography apparatus, enabling precise navigation to be provided as a support in examining or treating a person.
This object is solved by a method and a device comprising the features of the independent claims. Advantageous embodiments arise from the sub-claims.
In the method in accordance with the invention for determining the position of an object in a navigation system of co-ordinates, wherein in general one or more geometric points can also be seen as an object, one or more reference points which are also designated as markers and which exhibit a specific reaction or reflex behaviour with respect to a signal detecting device employed are connected to the object in a defined positional relationship. It is not necessary for the reference points or markers to be directly arranged on the object, which is not possible when the object is surrounded by an external body. In general, firmly attaching or fixing markers in a positional relationship which is as stable as possible, i.e. not easily shifted by the effect of external forces, for example to the external body, is sufficient. For example, one or more markers can be provided on a head to be examined via a special clamp arranged on the head. Such clamps are widely known and are designated as skull clamps or Mayarea™ clamps. In such an application, the markers can either be integrated into the skull clamp or arranged, for example attached, at a defined position in a defined positional relationship. These markers, firmly connected to the object or in a firmly defined positional relationship to it, can be used to determine the position of, for example, the external body in a detection system of co-ordinates, wherein the position of or changes in the position of the object of interest lying in the external body, for example a cerebral area shifting due to a change in the pressure ratios after the cranium has been opened up, also known as “brainshift”, are also detected in the detection system of co-ordinates. To this end, the position of the object is first determined and/or recorded with reference to the detection system of co-ordinates, i.e. for example with respect to a system of co-ordinates of a nuclear spin resonance device or of the detection area of an image recording apparatus, wherein the position of the reference points or markers is also determined with respect to this detection system of co-ordinates. The position of the markers can be detected before, after or at the same time as detecting the position of the object. Thus, a relative positional relationship between the detected object and the detected reference points or markers can be determined, such that the position of the object is clearly defined when the co-ordinates of the reference points or markers are known. The position of the markers is then determined in relation to a navigation system of co-ordinates, such that the markers can be exactly spatially localised, i.e. the co-ordinates of the marker or markers are determined in relation to a system of co-ordinates for navigation. Since the relative positional relationship between the object and the markers has been determined beforehand, for example in a nuclear spin tomograph, the absolute position of the object can be determined spatially using the navigation co-ordinates of the markers. In this way, the position of the object can be continuously determined, i.e. where the object of interest, for example a tumour or other area of tissue, is spatially located in relation to a navigation system of co-ordinates can be continually determined even, for example, after a person has been taken out of a nuclear spin tomograph, since the navigation system of co-ordinates is in a fixed and known relationship to the object to be measured. This can be advantageous in examination or treatment, since for example an instrument for treatment can be moved to a desired position relative to the object while simultaneously detecting the spatial position of this instrument for treatment. In accordance with the invention, the position of the object of interest is thus not “lost”, as is the case in the method in accordance with the prior art described above, but can for example instead be continually determined.
In the sense of the invention, however, it is not necessary to use the same reference points or markers in order to determine the positional r
Dombay Akos
Hartlep Andreas
Schmidt Robert
BrainLAB AG
Jung William C.
Renner , Otto, Boisselle & Sklar, LLP
Sykes Angela D.
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