General Electric Company

Mark E Riehl

Robert J Dobberstein

A patient alignment system utilizes stationary and mobile light fan beams for precisely positioning a patient for performing NMR studies. One assembly of preferably laser light sources is utilized to create a visible reference point for aligning a patient anatomical reference in the staged scan position. The reference position is then used as a reference to locate the scan volume and to automatically translate the patient so that the scan volume is in the optimum homogeneous region of the polarizing magnetic field. Two laser assemblies, each separately operable to provide a vertically movable laser fan beam, are used to locate a vertical reference point. The vertical reference point is used to retrospectively reconstruct images centered in the field of view. The vertical reference point is used to obtain prospectively image data to reconstruct magnified zoom or unmagnified images offset from the isocenter.

Patient alignment system for NMR studies

An x-ray receptor is translatable in x and y directions relative to the angulation axis of an x-ray source. Servo motors angulate the source and receptor coordinately with translation so the central ray of the x-ray beam from the source will be perpendicular to the input plane of the receptor when an x-ray exposure is made. New circuitry prohibits making an exposure until the source and receptor are properly angulated. Potentiometers develop signals corresponding with x and y distances and these are divided to get a servo motor command signal corresponding with the tangent of the angulation angle .theta.. Potentiometers driven coordinately with the receptor and source produce respective sets of signals corresponding with true instantaneous or real time angles .theta. and tangent .theta.. The first tangent .theta. command signal is continuously compared with the other tangent .theta. signals and the first tangent .theta. signal is independently compared with the actual angle .theta. with separate window comparators. As long as any pair of signals do not compare, the x-ray tube power supply is disabled.

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Waukesha, WI, United States of America

Mark E Riehl