Patent ID: 6118843
Filing Date: 2000-09-12
Classification: A61B,H04N

Abstract:
A method of stereoscopically displaying radiographic images of the internal structure of an object and determining the spatial coordinates of a selected feature image inside said object, comprising the steps of:(a) producing a pair of radiographic images on the same object at slightly different angles, comprising:i. placing a high-energy radiation source to one side of said object and an unexposed radiographic film to an opposite or back side of said object so that said radiation source, object and film are aligned in a substantially straight line,ii. defining an X-Y-Z rectangular coordinate system in which the direction from the geometric center of said film to said radiation source approximately defines the Z-axis, the film width direction defines the horizontal X-axis direction, and a third axis perpendicular to both X- and Z-axes defines the transverse Y-axis direction;iii. attaching a lead marker G to a proper position on the front surface of said object facing said radiation source so that the image of said marker can be detected by said radiographic film for the purpose of serving as an image reference point;iv. generating a first image by irradiating a high energy radiation beam from said radiation source through said object and finally reaching said film with said marker G forming an image point g.sub.1 in said first image;v. generating a second image by replacing said exposed film with a second unexposed film, shifting said radiation source horizontally along the X-axis direction with respect to said unexposed film by a small displacement B, and exposing said second film to a radiation beam from said radiation source under a substantially identical exposure condition with said marker G leaving an image point g.sub.2 in said second image;(b) using image display devices to present said first image, referred to as the left image, to the left eye of an observer and said second image, the right image, to the right eye of said observer so that the two images can be observed by the left and right eyes separately and simultaneously; said two images being set up in a definitive orientation so that, when viewing with both eyes, the two eyes of an observer form a line being substantially parallel to the X-axis; said two images being provided with two stationary, transversely aligned reference lines, referred to as the left reference line and right reference line, respectively, across the image plane in the Y-direction;(c) using two distinct optical paths to permit viewing of said left image by the left eye and said right image by the right eye both separately and simultaneously;(d) performing and measuring horizontal shifting motions of said two images and obtaining the coordinate (X.sub.GA,Y.sub.GA,Z.sub.GA) of an internal feature A with respect to marker G according to the following procedures:i. Shift both images simultaneously in congruence in the X-direction while observing the right image by the right eye only until the right image point g.sub.2 of marker G falls on the right reference line;ii. Shift the left image only in the X-direction while observing the left image by the left eye only until the corresponding image point g.sub.1 of said marker G falls on the left reference line and then shift one image with respect to the other in the Y-direction until the two marker image points g.sub.1 and g.sub.2 coincide and merge into one image point g, the two reference lines coincide to appear as one reference line, and a three-dimensional perspective of the images is developed;iii. Observe by both eyes while horizontally shifting the left image slightly with respect to the right image until the reference line appears at the same depth as the image point g of said marker G and use displacement-metering means to measure and record a travel distance P.sub.G of the left image;iv. Shift said two images simultaneously in congruence in the X-direction to bring an image point a.sub.2 of an internal feature A of interest on said right image to fall on said right reference line;v. Shift said left image to bring the corresponding image point a.sub.1 of said feature A in said left image to fall on said left reference line while observing by using the left eye only;vi. Observe by both eyes while shifting said left image slightly with respect to said right image until the left reference line appears at the same depth as said feature A, record this travel distance of said left image as P.sub.A, and then obtain a relative image shift quantity defined as .DELTA.P.sub.GA =P.sub.G -P.sub.A ;vii. Use the formula Z.sub.GA =(H/B).DELTA.P.sub.GA to calculate the vertical depth or Z-coordinate, Z.sub.GA, of said feature A with respect to said marker G, where H is the vertical distance from said radiation source to said front surface of the object;viii. Use displacement-metering means to measure the X-directional separation .DELTA.X.sub.ga between the image point g of said marker G and the image point a.sub.1 of said feature A on said left image, define F to be the vertical focal length between said radiation source and said radiographic film while being exposed to said radiation beam, and then use the following formula to calculate the X-coordinate of said feature A: ##EQU11## ix. Measure the Y-directional separation .DELTA.Y.sub.ga between said image point g of G and said image point a.sub.1 of A on said left image, draw an imaginary vertical line from said radiation source to said radiographic film while being exposed to said radiation beam, define and measure Y.sub.G to be the Y-directional separation between G and said imaginary vertical line, and use the following formula to calculate the Y-coordinate of said feature A: ##EQU12##