The invention concerns a method and an arrangement for determining the position of a marker in an organic cavity, in particular for establishing local passage speeds within the framework of the medical diagnosis of the stomach-bowel tract. The object of the invention is to provide a solution which ensures position-determining accuracy of greater than 1 cm in all three co-ordinate directions and permits position-determining times of 10 seconds and less in each case. According to the invention, this object is achieved in that at least one coil is acted upon in a time interval in a pulsed manner by current whose sign changes in each case between two current pulses, when the primary magnetic field, of the coil, produced thereby has died out to sufficiently low values. The secondary magnetic field generated by a marker is measured separately at least once by anisotropic magnetic field sensors parallel and perpendicular to the coil axis. The coil arrangement is displaced relative to the marker until the magnetic field sensors used to determine the radial component of the secondary magnetic field of the marker supply a zero signal and the associated position of the coil axis and the associated measured values supplied by the magnetic field sensors used to detect the secondary magnetic field component of the marker, which component runs parallel to the coil axis, are stored and fed to a display.
The invention relates to a method and an arrangement for influencing magnetic particles in a region of action. Methods and arrangements of this kind can be used to determine the spatial distribution of magnetic particles in the region of action or to heat up the magnetic particles locally. If, in addition to the magnetic particles, there is also interfering material in the region of action then this material may heat up in an unwanted way. To avoid unwanted heating-up of this kind, any interfering material that may be present is detected beforehand. If there is interfering material present, then an examination or investigation, or treatment, can be carried out with changed system parameters.
The invention provides a marker whose position in a cavity inside of a living organism can be determined, in particular for detecting local passage speeds of the marker through the gastro-intestinal tract, preferably in the small intestinal tract. The object of the invention is to provide a marker whose magnetization can be reversed with relatively low field intensities. To that end, the marker consists of a first substantially spherical part which contains a magnetizable material and is surrounded on all sides by a second part which is provided with a substantially spherical receptacle adapted to the surface shape of the first part, the receptacle being filled with a low-viscosity fluid.
The present invention concerns a method for eliminating interference in measuring signals (S.sub.M) which are corrupted by pulsed interference signals (S.sub.ST) having a known or determinable interference pulse interval (T.sub.St), whereby the detection period (.DELTA.t.sub.E) of an individual measured value (E) is shorter than an interference pulse period (.DELTA.t.sub.St), and a plurality of individual measured values (E) is detected at freely selectable time intervals (T.sub.E) of the measuring signal (S.sub.M). A reliable elimination of interferences caused by radio-interference sources transmitting in a pulsed manner is achieved by detecting at least three consecutive individual measured values (E) at time intervals (T.sub.E) that differ from the interference pulse interval (T.sub.St), and by determining an interference-filtered measured quantity (M) with the at least three individual measured values (E).
A system and method for bracketing a tissue volume (22) and later locating the bracketed tissue volume. The system includes a plurality of markers (30) and a probe (32) and detector (34) for use in locating the markers by providing information usable by a surgeon that is representative of changes in proximity between the probe and the plurality of markers. The markers have various detection characteristics, e.g., they transmit gamma rays, that are detectable by an associated probe and detector. The tissue volume is removed by manipulating a cutting tool based on the proximity information provided by the detector which can be used by the surgeon to define the boundary of the tissue volume. A two-part cutting tool (200) is provided for removing the tissue volume, and a tissue anchor (300) is provided for stabilizing the tissue during removal. The system and method of the invention are particularly useful in bracketing and then removing a tissue volume from amorphous, pliable tissue such as breast tissue.
A system and method for bracketing a tissue volume (22) and later locating the bracketed tissue volume. The system includes a plurality of markers (30) and a probe (32) and detector (34) for use in locating the markers by providing information usable by a surgeon that is representative of changes in proximity between the probe and the plurality of markers. The markers have various detection characteristics, e.g., they transmit gamma rays, that are detectable by an associated probe and detector. The tissue volume is removed by manipulating a cutting tool based on the proximity information provided by the detector which can be used by the surgeon to define the boundary of the tissue volume. A two-part cutting tool (200) is provided for removing the tissue volume, and a tissue anchor (300) is provided for stabilizing the tissue during removal. The system and method of the invention are particularly useful in bracketing and then removing a tissue volume from amorphous, pliable tissue such as breast tissue.
