X-ray image correction apparatus

Claim 1

An X-ray image correction apparatus comprising: display means (4, 6, 15) for monitoring an X-ray image; first memory means (2) for storing in the digital form a first X-ray image of an object taken before the injection of an X-ray contrast medium into the object; and second memory means (1) for storing in the digital form second X-ray image of the object taken after the injection of the X-ray contrast medium into the object, subtraction means (3) which is connected to the first and second memory means (2, 1) to execute digital subtraction between data of the first and second X-ray images, providing data of the subtracted X-ray image of the object, characterized in that it further comprises: means (7, 8) for defining a specific region in one of the first and second X-ray images by monitoring the same on the display means (4, 6, 15); means (3) which is connected to the subtraction means (3) and also to the specific region-defining means (7, 8) so as to obtain an error criterion by calculating an error-evaluating function with respect to a degree of pattern coincidence between a pattern of the specific region of one of the first X-ray images and that of the remaining X-ray image which corresponds to the specific region of the first mentioned X-ray image; and control means (10, 11) which is connected to the means for obtaining the error criterion and controls to derive one of the first and second X-ray image data stored in the first and second memory means, for further subtraction processing in such a manner that the error criterion is minimized.

Claim 8

An apparatus for displaying a subtracted images comprising: imaging means for obtaining a plurality of images of an object; first storing means (1) for storing a first image which is one of the images obtained by said imaging means; second storing means (2) for storing a second image which is one of the residual images obtained by said imaging means; addressing means (10) for providing first and second addresses sequentially to said first and second storing means, each pair of addresses assigning a pair of pixel data in said first and second images to be readout from said first and second storing means (1; 2) respectively; and subtracting means (3) for obtaining a subtracted image between first and second images by subtracting one of the paired pixel data from the other one read out from said first and second storing means (1; 2), a display device (4; 6) coupled to said first storing means and/or subtracting means so as to display said first image and/or said subtracted image, characterized in that it further comprises: cursor means (8) for providing a cursor signal to said display device so as to superimpose a cursor pattern on the first image in the display device indicating a limited region of the first image; designating means (7), coupled to said cursor means (8), for designating a relative position between said first image and signal limited region of said first image; calcuating means (9) for calculating an error degree of displacement between said first and second images using said subtracted data belonging to said limited region; and means for adding a relative address to one of first and second addresses, said relative address being so derived from said degree of displacement error as to minimize said degree of the displacement error between first and second images.

Claim 9

An apparatus for displaying a subtracted images comprising: imaging means for obtaining a plurality of images of an object; first storing means (1) for storing a first image which is one of the images obtained by said imaging means; second storing means (2) for storing a second image which is one of the residual images obtained by said imaging means; addressing means (10) for providing first and second addresses sequentially to said first and second storing means, each pair of addresses assigning a pair of pixel data in said first and second images to be readout from said first and second storing means (1; 2) respectively; and subtracting means (3) for obtaining a subtracted image between first and second images by subtracting one of the paired pixel data from the other one read out from said first and second storing means (1; 2), a display device (4; 6) coupled to said first storing means and/or subtracting means so as to display said first image and/or said subtracted image, characterized in that it further comprises: cursor means (8) for providing a cursor signal to said display device so as to superimpose a cursor pattern on the first image in the display device indicating a limited region of the first image; designating means (7), coupled to said cursor means (8), for designating a relative position between said first image and signal limited region of said first image; calcuating means (9) for calculating an error degree of displacement between said first and second images using said subtracted data belonging to said limited region; and means for adding a relative address to one of first and second addresses, said relative address being so derived from said degree of displacement error as to minimize said degree of the displacement error between first and second images.