John W. Strohbehn

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In order to increase understanding of artefacts caused by patient motion in computed tomography, rigid translational and rotational motions in the plane of reconstruction have been considered. Motion artefacts were simulated on a digital computer and demonstrated in actual CT scans of a phantom. The types of motion artefacts observed included streaking,(More)
A computer-based system has been developed for the integration and display of computerized tomography (CT) image data in the operating microscope in the correct perspective without requiring a stereotaxic frame. Spatial registration of the CT image data is accomplished by determination of the position of the operating microscope as its focal point is(More)
A new system, which we call the frameless stereotaxic operating microscope, is discussed. Its purpose is to display CT or other image data in the operating microscope in the correct scale, orientation, and position without the use of a stereotaxic frame. A nonimaging ultrasonic rangefinder allows the position of the operating microscope and the position of(More)
Implementation of a Vicom-VME image processing workstation for the frameless stereotactic operating microscope system has allowed an improved interpolation algorithm for more accurate reconstruction of three-dimensional data, the integration graphically of multimodality imaging information, an additional stereotactic graphics display outside of the(More)
The frameless stereotactic operating microscope has expanded the potential application of modern stereotaxis to procedures outside of the intracranial compartment by removing the constraint of a rigid frame. We studied seven patients all of whom had a history, examination, and imaging studies consistent with lumbosacral spinal pathology for which they(More)
An oncolytic effect of hyperthermia in the 42 degrees to 43 degrees C range has been previously demonstrated in cell culture and animal models. To apply this modality clinically, an interstitial microwave antenna array system has been developed for the delivery of controlled hyperthermia to an intracranial tumor volume, and a Phase I clinical trial(More)
Accuracy of a stereotactic operating microscope, by which imaging data may be superimposed on the operative field without a stereotactic frame, has been most limited by the resolution of imaging information. Using newer algorithms and pilot pole calibration of the digitizer, an error in registration of 2 mm and in contour display of 3 mm has been(More)
Three interstitial hyperthermia systems were compared on the basis of their abilities to heat tumors: ferromagnetic seeds, microwave antennas, and rf electrode needles. The theoretical calculations were performed using two-dimensional tumor models containing static tissue and electrical properties and various blood flow patterns. Basic assumptions were kept(More)